Trouble shooting a misfire code P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308

For the new play by play misfire video click here:
• Why does my car engine...
Misfire Trouble Shooting: 30 to 60 minutes
If your car is running rough at idle or hesitating during acceleration, there is a good chance that it is misfiring. Most of these car motors function on 100 year old basic principals of a combustion engine. They need the proper mix of AIR, FUEL, SPARK, COMPRESSION and TIMING to operate smoothly, in all of it's cylinders.
This video will show and explain how to narrow down your possible problem.
For instructions on how to do a compression test, follow the links below:
• Compression Test on a ...
• How to do a compressio...
Fuel Injector Testing:
• Checking your fuel inj...
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Disclaimer: • In this video I share ...
Basic car care KZbin channel: / rspiwin
How to search my videos: • How to find videos on ...
Visit my Website for special tools, my wish list and other helpful information: www.RobertDIY.com
Support Robert, become a Patron: / robertdiyafterdark

[@Artemio54321]

dude i never heard someone talk so clear and to the point . extremely informational.

[@RobertDIY]

+Artemio54321 thanks for watching.

[@feliperodriguez2861]

agree ! very helpfull tips..

[@Cdmasphuck]

@@RobertDIY What should I do I have a 2013 dodge charger police 5.7 v8 with only 53k miles I replaced the #5 coil. they changed the spark plugs at 48k according to carfax and looks like the replaced #5 injecto newer looking compared to the rest. They probably couldn't figure out the problem or didnt want to dump more money into it and that's probably why it got auctioned off. Any advice or suggestions? Should I get extended warranty and try getting them to fix something like that?

[@erickapoppe9696]

Hello! I’m trying to fix my own Mr2 that is misfiring. Check engine light is flashing... this looks like it is so very clear even to a girl like me that’s never tried to fix my own car can handle it maybe.. lol . I’m not giving up! I’m grateful! Ty

[@eyeofbast]

Thank you for explaining to the point and not skipping over an obvious a mechanic wouldn’t think to relay to someone trying to learn this stuff. Great video!!

[@RobertDIY]

You are welcome.

[@ramonkoeshall6862]

Robert I am taking a performance and driveability college class and this video matches what is being taught in class. I enjoyed your video.

[@RobertDIY]

I have a new version of this video that has more show and tell: Trouble shooting a misfire, Code P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308

[@pdbrown170b]

This was the most lucid explanation of misfire codes and means of troubleshooting them that I have come across. Thank you for taking the time to do this video.

[@RobertDIY]

+Pete Brown Thank you for watching.

[@davescott6159]

Thanks for the tips! I had a P0302 Misfire on Cylinder #2 on my 2003 Ford F150.My truck was shaking at 45mph and blew a service engine soon light on a big hill. I changed the spark plug and the coil pack. That was it, upon further inspection the old coil pack had a crack in it. I saved alot by doing alittle troubleshooting, also wanted to suggest to others that if you dont have a code reader to go to Autozone, they would be happy to read the code for you!

[@VincentArdolino]

This guy is a great teacher. so simple but super educational. I've never heard such simple complete explanations of the entire engine operations and common problems throuout the motors fuel air and spark operations. Simple tricks to to make shot work of diagnosing common misfire related problems.

[@RobertDIY]

Thanks for watching.

[@oscardiaz8802]

Robert ! I have a 2002 ford Taurus I got for free im pulling a P0301 P0302 and a P0316 code could these misfires be fuel injectors I do smell fuel in my engine compartment sometimes

[@joseaponte6782]

I got 2006 ford f 150 5.4 engine put new coil and new spark plugs i still got there same problem code po 306

[@kennethbournosy3006]

I love how he keeps every little detail in perspective for advances to novice. Following now for 5 yrs.

[@RobertDIY]

Thank you very much for watching.

[@adudecalledjay]

Thanks for this video. Was really well thought out and articulated. Keep up the great vids!

[@RobertDIY]

Thank you for watching.

[@maniacalmonster2293]

Man so cool you replied. I am having an issue with my cylinder #3 misfire. Had it checked with autozones tool, more specific, telling me that it is the valve spring needed replacement. BUT they had the wrong mileage information so I'm thinkin cuz of that, the diagnosis was off? (crazy as it sounds) lol cuz I am actually sitting here right now cleaning the head valve cover and my coils all look perfectly fine. Of course, there could be a problem with the compression or release of the spring while motor running. I skipped the spark plug check because I have recently replaced them all within the last couple months. So, upon unmounting the fuel injector wire harness, I noticed that my fuel injectors slightly twist to the left and right. Is this normal? From your video I saw that the misfire could be the seals on the injectors. If that is normal, then my next test is compression I suppose. Any thoughts? 😁

[@CrzyMav]

I’m a Mechanic, with over 27 years experience. Now I have a 2008 Chevy Impala LS 3.5 Flex fuel model. Now this thing has been kicking my but from day one. I checked the Coil pack, it was faulty. Replaced. It ran great for a day then again...the same code popped up again.checked spark plugs and replaced them just to be safe. I also checked the wires and they are also new. Before that I switched the spark plugs and wires just to make sure they are working properly. I also did a compression test and leak down test. Passed no issues. I checked the injector and it was given me a low signal reading. Replaced all the injectors cause with over 150,000 miles I figure it was time. Ran great for another day next day. Same code. Cylinder number 5. Now I have gone thru the entire check list including checking the fuel pressure. 49-50 PSI with out a drop. I’m out of options and am stuck. The only thing ai have not replaced is the spark plug wires but they seem to work perfect and look brand new. I’m at a lost...I also checked the plugs etc. Did I or am I missing something here??? This is so frustcause I know what I’m doing and have worked on cars for years...but this one is kicking my but for sure.

[@RobertDIY]

ECU, ECM, Whatever they call it for that vehicle is probably bad.

[@MLoPeZ23805]

Thank you for making this video. I have a better idea of how to fix my misfiring #7 ..great work

[@RobertDIY]

+Michael Lopez Thanks for watching.

[@RobertDIY]

+Michael Lopez kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@hokehinson5987]

Your the man, used your videos to help fix a neighbors Volvo. That great 5 cylinder in line.

[@RobertDIY]

Great to hear!

[@bink2315]

I have a 2003 Nissan Maxima and I keep getting the PO300 code I changed the intake gasket, I changed the O2 sensor that is in the front of the car connected to the cat closest to the oil pan, I have changed the crank sensor and I put in new plugs twice and all three plugs on the fire wall side are black again so I'm lost, first I was thinking it was a ground of some sort but I can't find that, the car was running just fine then coming home from work it just would not perform it was like it just lost power under acceleration Oh and I forgot I changed the #3 coil that was the first thing I did as I got a code telling me the misfire was #3 coil, any help you can give I would love. Thanks Charles

[@RobertDIY]

Charles McGowan Jr. Hi Charles. Is the car hard to start hot or cold? How many miles does the car have?

[@bink2315]

8th miles, it starts right up no issues hot or cold it just has no power under acceleration it will move but misses like crazy

[@RobertDIY]

Are you running 91+ octane? How many miles does the car have?

[@bink2315]

The car has 81k, it always gets 93 octane never had anything less than the 93 octane

[@bink2315]

I had did all those changes it ran great for a week then boom on the way home it just lost power under acceleration I was still able to drive it back home it had been sitting now going on 2 weeks I just can't figure it out, I did once have the PO420 code so I changed the sensors mentioned in the original description all the plugs on the firewall side were black and they were new not even a week old so I got new ones same result and they never seen the road only missing when I press the Gas about 3k on the engine

[@mariapeak236]

Robert, Very informative and clear video. I just bought a used 2017 Ford Edge 2.0L turbo with 114,00 miles on it. It was running great... could not even feel or hear the engine running. Then just the other night I was taking it out and it was running fine until I had to give it the gas to merge onto the highway and it just started shaking and sputtering and running Very rough the check engine light came on and went off and came on again. I went to Auto Zone right then and there, a Very short distance from where this started happening, they put the check on and it came up with: PO332, knock sensor 2 circuit low input (Bank 2), Secondary DTCs, PO300: Random Misfire Detected, PO302: Cylinder 2 Misfire Detected, PO: Cylinder 3 Misfire Detected. I do not have a reputable mechanic that I can go to. What does all these codes mean.? The check engine light keeps going on and off. This was so sudden. I just got this car in Oct. Hoping you can help me.

[@RobertDIY]

are you running premium fuel?

[@FPVREVIEWS]

Thanks, robert. i have a misfire on cyl #1 on my volvo 850 non turbo 1997, so this is very helpful. i've ordered parts for an ignition tuneup, but i'm not sure because i lose power, and run rough, and get eh light coming on with the p0301 code, and a flashing check engine light, but the problem only happens when the car is hot, after running for a while. seems weird. runs great cold. for the first hour around town. then starts to run rough, etc. it gave me codes for most of the cylinders first, not sure how long they had been there, but they have not come back. the one that keeps coming back is the p0301. anyway, thanks for the great video.

[@RobertDIY]

Ignition parts is likely what you need.

[@FPVREVIEWS]

I think i have a bad coil. it's got white marks on both sides, and i can see a blue glow on the sides as well in the dark, so i'll replace its, and oem plugs, wires, cap and rotor while i'm at it, but i 'm pretty sure the coil is the problem. thanks so much for your vids. they have been a great help, and i'll let you know how it works out!

[@FPVREVIEWS]

so. i replaced the coil, and i see no sparks in the dark, but the car runs the same, so i replaced the distributor cap and rotor, and still the same. i then swapped the spark plugs that were autolite platinums for bosch platinums, and bingo, problem gone! amazing how sensitive the motor is to the plug type. .. a function if high compression engine? don't know, but the cylinders average about 200lbs, so i guess that's pretty high for a gasser. still have more issues with the car, but wanted to thank you again for your help, robert! you are a real benefit to everyone with one of these cars!

[@RobertDIY]

Glad you got it sorted out.

[@geraldvandendungen8913]

Robert, I have give you a very big thanks for making this video cuz without you I wouldn't have been able to pinpoint exactly what my car was having issues with. I knew cylinder one was misfiring but beyond that I wouldn't have figured out that it was just a coil. Excellent video. Subscribed & liked! Again, THANK YOU. Saved me a ton of money

[@RobertDIY]

+Gerald Vandendungen you are welcome, thanks for watching.

[@topgunnmom1]

You're a good teacher! I don't know anything about cars, but was checking for information about misfiring. Keep up the good videos!

[@RobertDIY]

topgunnmom1 Here is another video that I did with more show and tell. - kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@jamesfreeman1663]

Excellent description of trouble codes (random misfires) in question along with excellent diction...I'll be back for more diagnostic tips...

[@RobertDIY]

Thanks for watching

[@thetruth888]

By far the best instructional video/ instructor. You explained it crystal clear and easy to understand, THANKS FOR THE KNOWLEDGE! Appreciate it.

[@RobertDIY]

+The TRUTH Thanks for watching and for your kind words.

[@fred306801]

This is one of the best well explained videos I have seen so far. Love the way you went step by step. At 100k the Ford Sports track 6 cylinder started running rough. So I put new wires plugs and changed the oil air gas filter. Ran much better. Except at take off. It would sputter and shake. Sometimes completely stall out. After 10 to 15 min of sitting she would start up and run fine. Took it to a auto parts store and they put it on the machine and found nothing. No engine light or anything. After appox. 5k miles the engine light came on. So I took it back. This time they got a trouble code p0303. And gave me a two page list of things that it could wrong. When I get some time I will try what you suggested. Thank You for posting. Thumbs up ! 10 starts ! Awesome video.

[@RobertDIY]

***** Thank you for watching.

[@AdamSpiker1]

Man this is awesome. I’m chasing a misfire on startup on cylinder 1 (occasionally #5) on my Land Rover LR3 and you did an awesome job explaining. Thanks!

[@RobertDIY]

You are welcome

[@gabrielalanbaker]

You saved me a lot of money my friend. I had a bad coil and fixed it easily with the help of your video. Thank you!

[@RobertDIY]

Gabriel Baker Good deal. Thanks for watching.

[@roberthitt4653]

Excellent thorough video. I wonder if there are any statistics that show the probability of what specific problem causes a P0301/2/3/4/5/6/7/8 type code? For example: spark plug causes this code 20% of the time, or possibly 60% of the time. Likewise for the coil, and other possibilities. I know this would likely be different for different vehicles, but a general probability over all vehicles would be nice to have.

[@RobertDIY]

owners neglecting maintenance.

[@msbutterfly714]

So I called the Mazda dealership (putting it off because I know how much they charge $$$) and just to hook up the code reader they wanted $99.99 and of course told me that this would go to the fixing of the car. Like that would appease me in some way ?? Anyhow I am on google or youtube all the time whether it be doctor related or car related as DIY pays off sometimes. I am so very thankful that you put this video together as I am still reluctant to take my car to the dealership and charge me mass amounts of money to fix something I can do myself. Anyhow, I thank you Mr. Robert I really appreciate this video and I hope to get my 2005 Mazda 3 running great again as I have 220K miles on her but I have taken good care of her and will continue to. God Bless you and yours. Be well.

[@RobertDIY]

+msbutterfly714 thanks for watching. Most auto parts stores will check your codes for free.

[@cass71291]

Sir, Just wanted to say a sincere thank you for taking the time out to educate us out here. Very well explained. Tomorrow will try these tips to diagnose Code P0302- Cylinder #2,o my son's 2002 Mitsubishi Lancer. HOOAH!

[@RobertDIY]

Thank you for watching and I hope it is something simple.

[@decibelchild]

I feel like i have learned a lot, i have a busy saturday ahead of me, thanks Robert!

[@RobertDIY]

OK, thanks for watching.

[@thomasthomas9077]

Excellent you tube. My car in shop now for P0303. Lexus 300ES. Because it takes a ton of work to get to the coil for the 3 Cylinder I’m changing all 3 in the back.

[@RobertDIY]

Good call.

[@Mrlakers0834]

Thanks for the reply Robert. I added the bottle at the gas station. I had about 4 gallons of gas already when I added the bottle of injector cleaner then I added another 13 gallons to fill up my tank. The bottle said it works up to 15 gallons of fuel. I have a lexus is300 2001

[@RobertDIY]

Mrlakers0834 That's a perfect way to do it. Your problem is likely unrelated. What codes are present.

[@jadenbverghese8664]

Robert,the videos are informative, thank you. I have a 2003 Toyota Highlander(V6) with 145k miles. Past year the engine light has been on and the diagnostic trouble code report shows P0171/P0300/P0301/P0303/P0305.My mechanic had couple of tries to fix the misfire but the light comes back on.

[@RobertDIY]

jaden b verghese What has been done?

[@tedwoghiren4002]

So precise. Just who I needed to listen to. I'll now get a compression test kit to check my Mazda 6 2.0 petrol. Thanks

[@RobertDIY]

Thanks for watching

[@JESUSVALDEZCARRANZA]

tried everything that you said on my Dodge caliber which had a misfire cylinder 1 and I felt shake, loose of power, and smelling. I didn't use the compression gage just the swapping of the coils and that completely fixed the problem

[@RobertDIY]

Good deal.

[@ryanphaup5932]

How your car knows that there is a misfire is that when a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring. Thanks for the straight-to-the-point video ;)

[@RobertDIY]

Thank you for sharing.

[@landontesar3070]

Thanks, Ryan, am experiencing that with my Dodge Caravan and P0303 code. It's slight but evident. Interesting.

[@bcstephens96]

Wow. That has to be one of the best general, broad, give-me-some-idea-where-to-look troubleshooting videos I have EVER seen. Good job. :)

[@RobertDIY]

+Apple Junior thanks for watching

[@RobertDIY]

William C, I could NOT reply to your post. You must have some kind of setting permitting that. The short answer is no. It can cause the spark plug wire to malfunction but not effect compression. The spark plug treads seal the cylinder area and the oil leak would be above the threads. What kind of car do you have?

[@clementealvarado6640]

Robert DIY. This is my first time watching you video about random misfired-- and you did explained everything perfect every way off misfired problems ,, I do appreciate this video it give me lots of ideas of what exactly wrong with my 2007 ram 5.7. Is Ben running rough this past weeks

[@RobertDIY]

+clemente alvarado ok, thanks for watching. I hope you get it figured out.

[@supertiger1100]

Good video. 1998 chevy S10, It's been missing and finally gave a misfire code for number 2. Doing the broom handle to the ear thing a very noticeable tick can be heard. I suspect a stuck valve. Any way the broom handle test it pretty good determining whether it's inside the engine or something outside. Hold the wooden stick to your ear and touch non-moving parts of the motor to narrow your search!

[@RobertDIY]

+shadetree mech Old school methods. lol

[@Commander76]

Most informative video I've ever come across on KZbin.

[@RobertDIY]

Glad it was helpful!

[@michaelhamilton5554]

Robert, I have a volvo 2004 s40 t5 2.5 turbo. I'm have intermittent miss fire that isnt trip the cel. I took it to autozone and attached it to there scanner and got the p0303 code. I notice the problem most when I first run the car prior to halfway on my temp gauge. I'm going to look at the spark plug and coil but just thought I would pick your brain. I love your videos and thanks for helping us out.

[@RobertDIY]

Michael hamilton I would check plug and coil first. Maybe swap them with #5.

[@EricStorms]

Hi, Robert. Great video as always! Quick question: do you have to do anything special when connecting the OBD-II scanner? When I connect to mine (2000 Volvo S70 GLT) it trips the immobilizer, preventing me from being able to turn on the engine. I have to pull the fuse (#4) to get it to start again. Thanks!

[@tedharralston1081]

I know you made this some time ago, but I really liked it and you did a great job

[@RobertDIY]

Thank you!

[@thestreetfighter524]

Thank you Robert that was very informative post about a misfiring engine. It was a thorough diagnosis that can usually be missed even by a seasoned mechanic. I have subscribed to your channel. Great day

[@RobertDIY]

thanks.

[@Muilisxx]

I have to really say this video is fantastic. You really know how to explain things. I'm not a complete noob when it comes to cars and stuff but there's still things I could learn and this is one of them. From a semi-pro stand point I can honestly say this is by far the best video on this subject. As I said b4 my 99 chevy s10 is throwing this code. I JUST bought the truck a few days ago and it does hesitate to start SOMETIMES and those times it does is prob when its misfiring. It does shake during idle but only when warming up from a cold start. I asked the previous owner when he had the plugs changed and he said 1 year ago but who knows if it was done properly or had a completw tune up. I'm wondering if a complete tune-up will solve this issue. It's not throwing 301-306 so not sure which cylinder it is as 3000 means random / multiple so I hope I dont have more than 1 misfiring. What do you think?

[@Muilisxx]

300*

[@RobertDIY]

+Muilisx How many miles on the truck? I would probably do a full tune up and replace the fuel filter. Coil packs are probably due replacement. Also, it may have the wrong plugs in there. Sometimes people get sold high dollar iridium plugs and the vehicle has trouble running on them.

[@RobertDIY]

+Muilisx kzbin.info/www/bejne/nZy0qZaGZd6Ze8U

[@RobertDIY]

+Muilisx kzbin.info/www/bejne/fn6QiJecrLCbkLM

[@Muilisxx]

The truck has 90,000 miles but on the new engine. The original engine had close to 200k.

[@lucasstech5833]

Hey Robert, thanks so much for your videos! They are awesome. I just bought a 850 AWD, worked great but now a have a misfire and smoke coming out of the tailpipe, i ordered the PCV kit and new spark plugs beforehand, is that going to fix the issue? I was wondering where you got your little code reader, i can’t seem to find it anywhere. Thanks so much in advance Bests

[@RobertDIY]

kzbin.info/www/bejne/hJuWZZeXoNSUr68si=fUwCbBX5WRYaNI6_

[@RobertDIY]

I have no idea what is causing the misfire. If you fix the problem then the misfire will go away.

[@RobertDIY]

kzbin.info/www/bejne/h5fIlJhql6qFbbMsi=0XlGP7WucLcw3cmt

[@RobertDIY]

kzbin.info/www/bejne/Y2PSeph_ndWJapYsi=-I2SDjCWmkorc036

[@Mrlakers0834]

Thanks for the input Robert, I added some lucas injector cleaner yesterday and filled up the tank and it idles weird when I accelerate and now I get codes p0300 and p0306.

[@RobertDIY]

Mrlakers0834 What kind of vehicle do you have? Did you add the Lucas then drive to get gas or add it at the gas station?

[@scindian1000]

Great information Robert. Very informative & precise. Thank you very much.

[@RobertDIY]

Thank you for watching.

[@jimmyismealright]

awesome i found out my wire on my fuel injector is bad on cylinder 1 but i wish i watched your video a long time ago because i have changed my wires, plugs, fuel injectors, coil and pcv valves lol thanks for the video

[@RobertDIY]

Glad you found it and thanks for watching.

[@RobertDIY]

Oscar, I can not reply to your message for some reason. You my have some kind of lock in your account settings. Could be several things. Go through the trouble shooting to narrow down the problem. - Trouble shooting a misfire, Code P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308

[@kp4xx]

You've outdone yourself again! Thanks got simplifying the mistletoes for is!

[@RobertDIY]

:) Thanks for watching.

[@Jeanphilip159]

thanks for all those tips! Its really easy to follow step by step even for a french guy :)

[@RobertDIY]

Good, thanks for watching.

[@csflmich2239]

Excellent presentation and information as usual Robert. Thank you!

[@RobertDIY]

You are welcome

[@yaroslavjouravlev2615]

Man, good instructions!!! I followed you on my misfires and got it fixed!, Thank you!

[@RobertDIY]

+Yaroslav Jouravlev good deal.

[@XXSomeDudeXX]

Robert DIY You give fantastic straightforward explanations. Subbed. My number 2 cylinder is misfiring but only in a certain RPM range and only when under heavier torque. Usually when I moderately accelerate without downshifting, or when going up a hill without downshifting. It doesn't usually misfire while cruising at speed or at idle. Do you have any ideas what it could be?

[@RobertDIY]

Abu Antar What kind of car do you have? You can start by pulling the plug and checking it. The video really explains it. You can also swap the plugs or coils around. - kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@XXSomeDudeXX]

I have a 2003 Hyundai Elantra 4 cyl 5 speed. (Forgot the displacement size). My scanner reads p0302. Yeah, you're right I need to pull the plug and go from there. I just wanted to pick your brain first because you obviously have a lot of experience. To me it would seem that the engine would always be misfiring if there were a problem with fuel/spark/compression. It's kinda weird that it only does it in certain conditions.

[@RobertDIY]

Abu Antar Probably a coil or bad plug. How old are the plugs (age and miles)?

[@RobertDIY]

Abu Antar The video is really already picking my brain.

[@XXSomeDudeXX]

All of the ignition stuff is factory, never been touched since i drove off the lot. Considering the misfire only happens occasionally it would make sense that its a bad plug or coil or something similar. Again, you dispense good advice thanks man. Now I'll get to checking it out.

[@mccfr]

I have an expedition but I like the way you explain how to check a miss fire

[@RobertDIY]

moises clara Cool, still the same process.

[@expsterm1]

Very good at explaining things with common man language.

[@RobertDIY]

thanks

[@vracerv]

Wish I could leave more likes. Very imformative. I have code 301, and will test it as suggested. Should save a pretty penny.

[@johnhiggins6403]

Hi Robert, great video, easy to understand!!! I have a question about my 2000 300M Chrysler. Seems to overheat at higher speeds and when I slow down engine recovers to a normal temp...Also, heat only ever comes out at a luke warm temp. Thanks so much, Jack Higgins

[@RobertDIY]

+John Higgins how long have you had the car?

[@natestarr9935]

Extremely thorough! Thank you for the in depth explanation!

[@RobertDIY]

You are welcome.

[@chunkyfather29]

Very informative and solid video presentation. I never seen anyway so intellectually captivating. You are a teacher for sure. You that said I would like for you to help me with a big problem. Jeep liberty 2008 130k miles. Within a week I changed due to failure Fuel pump in tank Water pump. Been getting for 1 years check engine light for p0302 misfire. Changed out 3 times coil, plug. Still getting fault code. Changed crankshaft position sensor didn't help. Add injector cleaner no help. Did compression test all 6 cylinder good 130psi. Did spark test all good.. I am frustrated beyond belief. About to order fuel injector

[@RobertDIY]

Chunky Father You can purchase a fuel injector pulse tester to see if the injector is firing properly. I would actually swap the injector with another location before replacing it. Are you running OEM plugs?

[@chunkyfather29]

Yes

[@RobertDIY]

Good. Try the injector swap. Does the misfire happen randomly or continual? Does the car shake at idle?

[@chunkyfather29]

Shake a little than stops, shakes again so forth.. gas mileage went from 310mpt to 230mpt. I 'll try the swap on Monday or Tuesday when AutoZone has them in stock. If figured if bad I could replace it there. This truck has given me so much heartache. Transmission went, right head gasket, fuel pump. Crack window. Ac compressor, heater core blew. Brake caliber froze shut. You name it

[@chunkyfather29]

been getting a low oil pressure light when idle. I have checked oil level and it's good. Change oil regularly. Last week I changed oil pressure switch. No help

[@grendizer5439]

I'm really like your way to explain the details... thank you so much bro

[@RobertDIY]

You are welcome.

[@RobertDIY]

No you should not. Are you connecting the scanner with the car OFF? Go to AutoZone or some big box parts store and have them scan the car and see if their scanner does the same thing. If so, you need to have something repaired with your car. If not, get a different brand scanner.

[@Mrlakers0834]

So I finally got the car checked Robert diy. .. I have a misfire on cyl 6 because my compression is low. I got it tested and it's at 75 psi. I think I'm gonna get my engine swapped for a newer one from Japan

[@RobertDIY]

Mrlakers0834 Good deal. Hope it works out well.

[@powerstuffup]

You sound like a honest mechanic. I would definately trust you with my car.👍

[@RobertDIY]

Thanks for watching

[@kp4xx]

I will when the weather gets better here, I'll post when i do! Thanks!

[@luciensenor9589]

Thank you for explaining. I have a toyota rav4 2002 I've a code p0300 after that the ECM not reading I replaced it to weeks ago same issue come back

[@RobertDIY]

You are welcome!

[@douglasmcumber8977]

Robert, your computer picks up misfire by monitoring crankshaft speed. As engine misfires, crankshaft speed changes. Your CKP picks up speed change and correlates speed change to position indicating which cylinder is malfunctioning

[@RobertDIY]

Interesting.

[@gideon360]

Wow! I was so impress on this gentle man's knowledge and explanation. Thank you Sir I have appreciate all your knowledge I sent it to my Fiance after hours of my explanation. :)

[@RobertDIY]

Thanks for watching and sharing.

[@Muilisxx]

man i wish i can bring my truck to you but im located in NY. I would feel very comfy with u doing the work

[@msbutterfly714]

+Muilisx Me too I wish he was around me as well :-) Hard to find such a thorough and honest mechanic

[@Muilisxx]

+msbutterfly714 yup, u can tell he would do honest work, and actually fix the problems

[@jcan234]

Very informative and straight forward. I appreciate you and will share on other social websites.

[@PigtubaROBLOX]

This video was very helpful, turned out to be a coil pack. Thanks for your posts!!!

[@RobertDIY]

Freddy Jones Cool, thanks for watching.

[@kaleidoscope8743]

You rock! learned so much. You should teach young people! Question: I recently got a 2006 Nissan Altima 2.5s 4cyl 223k miles on original engine. I have a timing chain. Immediately after purchase, I had a p0507 CEL code whenever I experienced a random idle surging in park at startup that eould self clear in 3 engine/drive cycles. Oddly this was incidentally resolved when i had to replace battery for low cold crank amps. The CEL light & 507 code cleared permanently after 3 engine driving cycles. Coincidentally I sometimes notice hesitation when i try to accelerate quickly (i.e. from a stoplight, or during driving to merge onto interstate ). The new battery did not fix/improve this. But the hesitation never causes a CEL code. A few weeks later, one morning I noticed a faintly rough idle right at engine crank, but the idle smoothed-out in about 3 seconds with no CEL - and idles & drives fine (except for that random hesitation at quick acceleration which never causes codes). Within a few more days it happened again and was rough idling at engine crank for about 5 seconds (much stronger this time and made CEL come on. The idle quickly smoothes out, I got my new battery retested and it is good. The alternator and starter tested good also. I got CEL codes at Advance auto. The P0303 cyl. misfire paired with p0420 catalyst system efficiency below threshold. This pair of codes are logged several times. Mo other codes

[@RobertDIY]

What do the plugs look like?

[@RobertDIY]

kzbin.info/www/bejne/hIjJfaOmbbOYrKs

[@wannabeangler]

Very good video! I have issues with my Ram 1500 having a #4 cylinder misfire. I took out plug, cleaned it, put it back in, and test drove. The idiot light did not come back on, but my truck chugged intensely between 40-45 mph. Once past that speed or before that speed, the truck runs fine. Your thoughts on this to help my limited mechanical experience would be super helpful. Thanks!

[@RobertDIY]

+wannabeangler What year is the truck? It can be anything. The light will tell you. Have the codes read and see if any are pending (not giving the light yet).

[@wannabeangler]

+Robert DIY ...'99 5.9 ltr 360

[@wannabeangler]

+wannabeangler p304

[@RobertDIY]

+wannabeangler kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@wannabeangler]

I didn't figure I had to mention the codes since the video pertained to the misfire codes. My mistake. Curious about one other thing, do happen to be in the Tidewater area? Your accent sounds a local good ole boy from York Co.!

[@maha77]

you mention at 05:30 your car on a tilted road causing misfires, I've been parking my car for several months on a hill, hardly using the car, and now I am getting multiple mis-fire codes, 300 through 304, could it be simply not parking on a flat surface and not regularly using teh car causing this? THANK YOU so much for this video, SO helpful..!

[@RobertDIY]

+maha77 No, my car was running out of gas on that slant.

[@RobertDIY]

+maha77 kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@AZACE21]

Great video!I subscribed! Thanks so much for all the helpful videos you post!

[@RobertDIY]

+SuperDave520AZ you are welcome

[@sigmatricky8582]

You are very thorough. I have a 2014 Ford Fusion. It quit while driving after 100 miles of driving. This shop put a high pressure fuel pump on it & new plugs after diagnostic. It started & ran for 6-9 seconds. He shut it off. I sent it to the place where I got the car. They found contaminated gas. They dropped tank & cleaned lines. It's running but when I accelerate rapidly, I get engine light p0301 code. I told them to check gasket for leaks b4 it left shop. What would you recommend? Just broke & disputed at this point. Sorry so long of explanation !!!

[@RobertDIY]

Could be a bad / fouled plug.

[@sigmatricky8582]

I pulled code & it said misfire cylinder 1... With the fresh plugs from beginning would it have fouled out that quickly? I get no engine code at all until I get on it & then I start to get the hesitation/hickup!

[@RobertDIY]

kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@mrbioguy77]

Great video tutorial! Well organized and explained! Thank you!

[@RobertDIY]

+mrbioguy77 Thanks for watching.

[@yournightmare6515]

You are a good teacher! Thank you for this video. I learned a lot from it. : )

[@RobertDIY]

Thanks for watching

[@adamholland162]

Hi Rob, I have a P0301 Error Code on my '01 Volvo S80. The manual seems to be saying it's a misfire in cylinder 1. Any advice on this? THanks!

[@jilllagace5013]

I think Robert really knows his stuff!

[@RobertDIY]

+Jill Lagace thanks for watching.

[@d.m.traxler3472]

Thank you. I wish I could talk to you. This is one of the better videos I have seen

[@RobertDIY]

This one is better: kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@otisbrowniii8315]

Hey Robert. Thanks so much for another great and informative video. I have a couple questions for you. My s70 glt has a rough idle and I pulled the codes and had the usual suspects for the misfires, but more than one. p0300 for the general misfiring, but also 302, 304 & 305. I'm going to check the plugs, but I'm guessing that it'd be rare for all of them to not work at the same time. I also get a p0505 (idle air controller) and p0130 (circuit for front oxygen sensor. I think it's a vacuum/intake issue, but don't know where to start. There's a little smoke coming out of the dipstick and I know that is probably pcv, but I was wondering if anything else could cause that before I dig into doing that. Could it be the MAF? Intake air sensor? I'm still gonna check the plugs and wires, but I was wondering what order you'd go in to try and troubleshoot this. Sorry for the long question....

[@RobertDIY]

What year is your car? A multiple misfire usually points to a common issue. Could be a vacuum line is torn at the IAC, the IAC could be bad or some fuel/air mix issue. Did you do the glove test on the PCV? Volvo PCV System Check, 850, V70, S70, and others - Auto Repair Series

[@otisbrowniii8315]

Robert DIY Thanks for getting back to me. It's a 98 S70 GLT. I didn't do the glove test, but there is a little smoke coming out of the dipstick. Could that be from the misfiring by itself? Do you happen to have a video on IAC issues?

[@RobertDIY]

No, could be clogged PTC or broke vacuum line. Do the glove test. Chances are, you need a good tune up. When was the last time you changed rotor, cap & wires? The IAC can be cleaned but check real good for a vacuum line or hose tear.

[@otisbrowniii8315]

Robert DIY Ok.. spent the day checking out some stuff on the car. Did the glove test and the glove filled up and it went down a little when I removed the dipstick. Went into the plugs and there was a little oil that was coming down from the top, which I'm guessing is pcv related too. The hose is pretty hard and I had planned on tackling that soon. I also did the compression test and that worried me more. 1st cylinder shot right up to 180+, 3rd cylinder did the same thing. The 2nd on showed no pressure at all. I didn't check 4 and 5, but I'm guessing that it might be the same thing w them since I'm getting those codes. Any thoughts?

[@RobertDIY]

Ouch! I would quickly finish the compression test. If #2 has zero compression you likely have a burnt valve. If that is the case, you need to pull the head and install another one or have the one you have rebuilt. A lot of work. Did it on my daughter's S70 GLT. Her car had a mild head gasket leak. I have a full written tutorial and a video on the job. Takes time but it can be done at home. If 4 & 5 are also low or have zero, you need to figure out why the car burnt the valve. Usually it's a bad fuel/air mix.

[@charlesbracey2830]

Hi Robert, Great video, I have a 2001 Dodge Durango, v8, 5.9 liter 2 wheel drive, have misfire code, p0305. Pep boys, had truck 2 days, diagnosing misfire and could not isolate the problem.. Tested everything you listed in your video, Compression test on cylinder 5 was good, put in new spark plug, put in new fuel injector to test, problem still there, check wires, rotor cap and distributor, all good, did leak down test, no leaks on manifold gasket at #5 cylinder.. Checked everything and told me they could not figure it out, after a day and a half of searching for problem, I was told to take it to Dodge Dealer for a deeper look, is there anything else you could suggest, What about the PCM/ECU, out of everything I researched, that was listed as an option.. Any suggestions on how to check PCM/ECU, Any ideas on where to look next, the Vechile is in great shape mechanically, I do all of my maintenance and, it's a newly rebuilt engine with 71K miles on it, rebuilt by pep boys 5 years ago, new cats on both sides, does not leak or burn oil, was running great, until last week when it started to misfire at low speeds.. The misfire is greatly diminished and sometimes stops at speeds above 65 miles..At slow speeds, it's really pronounced.. Any suggestions on what to do when all of the above fails to resolve the misfire, you covered the subject well, but you did not speak to what to do if everything's tests good and the misfire continues.. I would really appreciate your response or anyone who has experienced the same problem with a 2001 Dodge Durango. Thanks.. Charles

[@RobertDIY]

***** If I were you, I would replace the cap and rotor with Mopar parts. This video is a little better. - kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@RobertDIY]

***** Then replace the wires.

[@ad356]

the mass airflow sensor does not control the air going through the engine, it measures the air going through the engine and uses that data to calculate air/fuel ratio of 14.7:1. just thought i would share that i caught that you said that. mass airflow are what i believe is a speed density system. the other way of measure air/fuel mixture is the MAP sensor but that is mostly found on older pre OBD II cars.

[@RobertDIY]

+andrew donohue It controls it at idle. If it's not working, it doesn't tell the computer what to do about air.

[@ad356]

it sends data to the PCM and tells the PCM how long to pulse the injectors thereby maintaining a constant 14.7:1 air fuel mixture. the MAF sensor is a big part of what controls the air fuel mixture and in layman's terms it does tell the computer what to do with how much air is entering the engine...... but it has no way of actually controlling the air, that is done with the throttle valve (butterfly). there are other sensors that are also part of air fuel mixture, sensors like the throttle position sensor, coolant temp sensor, air intake temp sensor, ect

[@RobertDIY]

I know that. But complicating the explanation to the everyday person will not help them. The average person doesn't need a FAR degree to tinker on their car.

[@ad356]

i dont have any automotive degrees of any type i just have spent hours researching the topic. i am someone who avoids repair shops at any and all costs. i refuse to pay someone $70 per hour when i truly don't have it. i work in a milk plant and watch management with their 80-100k per year jobs buying and driving brand new cars meanwhile i am driving a 2000 grand prix GTP with 160K+ and a 1996 camaro Z28 LT1 with 215K (the camaro is my baby no winters or salt but its high in mileage). in order to own and drive older cars like that on my wage i have to have a fairly advanced level of knowledge. i dont mean to argue but i prefer to stick to the absolute facts. sorry

[@RobertDIY]

No big deal. I just try to get people pointed in the right direction.

[@mundlkalli4396]

Can you fix my car? Excellent video. Easy to understand......no big technical lingo.

[@RobertDIY]

+mundl kalli Maybe. Thanks for watching.

[@sanjudabi4674]

Great Video, my problem is I get P0302, on cold start car runs good after going 60 mph or more 'something' cause misfiring and when I slow down can feel vibrations. However if I stop the car and restart the vibrations are gone and feels like engine running smooth. All breather hoses were replaced and also relay that is used for 2nd cylinder, however still same problem. Dont understand why the problem is cleared on immediate restart?

[@RobertDIY]

+Sanju Dabi Have you gone through all of the troubleshooting steps? - kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@ecmj58]

Great info man very helpful to know some of the reason my 02 Chevy Trailblazer have a misfire

[@RobertDIY]

Edward McMullen Thanks for watching.

[@TheMexicanFeeder]

Hi robert first off i wanna say great video it really helped me understand alot more then what i know ... But i drive a 2008 saab 9-3 aero 2.8L v6 turbo .. My car is giving me the P0300 code and also the P0303 code i heared these codes come up with a faulty catalitic converter but heres the problem i dnt have a cat i have a GS 3in downpipe and mid pipe ..... I just baught this car and it was running great untill now my car tuns great when i drive it normal but if i floor it or give it alot of gas it startes running bad check engine light starts flashing on and off .... Then it shakes at idle and starts acting weired what do u think is the problem with my car ?? Is it that i dont have a cat or i have to go thru all of the steps to figure out whats going on

[@RobertDIY]

TheMexicanFeeder Probably needs the plugs replaced and maybe the coil packs.

[@gmzx3]

How the he computer identifies a misfire is the signals from the crank angle sensor and/or cam sensor pick up the very slight slowing of the crankshaft when the misfire occurs (no power is produced from the misfiring cylinder). The ECU knows the crankshaft position and which cylinder was supposed to fire at that exact time and registers the error code and flashes the MIL if the misfire occurs a set number of times in a given period of time.

[@RobertDIY]

Thanks for sharing.

[@jaknel]

Very good video you done a great job. I have a 97 corolla 1.8 code P0304. I replaced plugs and wires still misfiring. Im thinking dirty or bad injector. Can U give me some help. Thanks

[@RobertDIY]

Check compression before you start tearing into the injectors. This new video shows it better. Trouble shooting a misfire, Code P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308

[@putraajim6558]

+Robert DIY

[@putraajim6558]

+Robert DIY

[@MasterA2042]

Robert, Great video man, I have a 2001 volvo s40 with 91k miles. The following codes came up...P0303 & P0015. The car pretty much runs perfectly, no stalling or etc, BUT it does take 3-5 cranks w/stepping on the gas pedal to start the car. Also, the muffler appears to be spitting some black stuff every once in a while (i dont think its oil) but maybe carbon. I fully charged the battery but will be replacing it tomorrow, I already replaced the spark plugs and tested the wires/coil for spark and they were all working. I had an oil change done as well........Any ideas on what to do next?

[@RobertDIY]

If you are still having a misfire, I would do a compression test. Compression Test After Engine Over Heated. Checking For A Blown Head Gasket - Auto Repair Series How to do a compression test on a car motor. Volvo 850, S70, V70 through 1998 - Auto Repair Series

[@MasterA2042]

Robert DIY Sorry for the mistake, I forgot to mention that my dad and I dont believe the car is misfiring. Do we need to do a compression test still?

[@RobertDIY]

If you are getting a misfire code, it's misfiring.

[@corygallagher8440]

I never comment on youtube videos or really ever sign in, but I wanted to let you know that this video is GREAT!! I'm a novice with cars but like to know what's going on if I have a problem so I have my own code reader, but when looking up the problems online it's usually really hard to get a straight answer and understand what's going on. Usually every page has a different answer in how to fix it but no real answer about why anythig is happening and this video defjnitely helped me understand how everythjng works even though it wasn't exactly the issue I'm currently facing. As a question that may you can help shed some light on. I have a e350 mercedes it is a v6, and I am having misfires but I am having misfires on all 6. I gfs codes p0300, p0301, p0302 ect all the way through p0306. It all happened at once I was at a stoplight and my idling started getting pretty rough and has been like that since. It's not an even roughness where it is constantly shaking but random sputters. So based on your video if know it's Probsbly an air or fuel problem. Is there anything simple I can check or based on how it is running? It had very good performance when I'm driving and not idling and I can go 60+ very smooth. Do you think maybe it's an idle speed sensor problem?

[@RobertDIY]

Those are very complicated vehicles. It could have something to do with the fuel pressure at idle as well. Try to find out if there is a way to check the fuel pressure. Some cars have a simple valve stem connection. If you have more than XXX miles, it could be the fuel filter getting clogged and low idle shows it.

[@corygallagher8440]

I just scanned the codes again and I'm running lean on both bank 1 and 2 as well.

[@zaydlakhani4018]

Hey ive been watching your shows you have posted on youtube and they are very easy steps to follow I have a 2000 volvo s40 im trying to install new conecters that plug into the coil pack the old conecters keeps sliding out and the wire keeps coming out a lil do u have any videos for that

[@RobertDIY]

No I don't. is something pulling on the harness? Can you add a little wire to the ones that are backing out?

[@zaydlakhani4018]

I would really appreciate if you can send me your email address that way I can send you a picture of the wires . Im not a real mechanic I been taking care of mycar just by watching your videos. Thank you

[@RobertDIY]

My contact info is on my website which is on the end of all of my videos.

[@zaydlakhani4018]

Ok thank u

[@MichaelBorne-rh8co]

Robert, you are the MAN! I got the 04 Volvo S40 1.9 and the car just idles like crap. Runs ex but at red light, awful idle. I need help! Have done the carbon cleaning real well and it worked for about a week. Any suggestions where to start or go next? DTC's are P0301 0302, 0303, 0304 and the P0171 as well. Thanks for any guidance or where to start or anything you can offer! I need the troubleshooting test sequence Robert! Thanks big guy!! BTW, I think the motor is the early 1.9, not the second gen later in the year of 2004 1.9L)

[@RobertDIY]

Mike Propst My guess is that you either have a massive air leak or low fuel pressure. - kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@MichaelBorne-rh8co]

Robert DIY Youre EXACTLY right. I found a vac leak. But Robert, its the little "S" hose, its right under the fuel pressure regulator and one end of it actually connects to the fuel pressure reg. The rubber part of this S hose had a big ol crack in it. I had to "make" one because nobody sells em and they're 20 bucks on ebay! It fixed the horrible idling crappy issue and now it idles bad but nothing like it did. Robert, do you think that regulator could've gone bad at 82k miles? I read the codes again and the p0171 is gone! And there was only 3 codes now. P0301, 302 and 304! But after I installed another "USED" regulator, it leaked gas everywhere so I had to put the old one back on. And then the cel light came on again but it was p0301, 302, 303 and 0304 this time. All four of the cylinders. I tried to check fuel pressure but my fuel pressure tester wouldn't adapt to the fuel line that drops on top of the fuel pressure reg! It leaked gas too! The regulator has that little screen at the top of it and thats cracked, the orings are little dryrotted, Do you think I need the new 125 dollar pressure regulator? Last question Robert, (if you even feel like answering), That pressure reg has to "seat" up in there. Can I make it do that without damaging it with big channel locks and how do I get that fuel line to go on my pressure gauge? I have some adaptors but they wont work on this Volvo fuel line to my fuel pressure gauge{ Thx!!!!

[@MichaelBorne-rh8co]

Mike Propst Oh yea, I forgot one thing Robert, if youre able to answer this I'd be so grateful again! The reader I have has recorded all sorts of things off of the s40's engine as I drove it until all the recordings were finished. So I have a lotttt of info on it now. Question is, would there be something in particular you would look for on the recorded graphs, short or long term like fuel trims, spark info, tps info or any of all that stuff? The o2 sensors seem good but I was wondering if there was anything in all that info I got recorded and freeze info that you might look for in particular? You're still the man Rob!! We appreciate ya over here in Col, S.C.!

[@RobertDIY]

I would replace the pressure regulator is you are still experiencing misfires. I have never replaced one so I don't know how to get the line off or on.

[@ahill007ny]

Hey Mike did u figure out what was going on? I have a 2001 Volvo s40 1.9t that's doing the exact same thing

[@kp4xx]

Not yet, it doesn't stall or hesitate when I drive it, drives a little rough but has good power when you gun it too!

[@koevidjinyaskoaugustine6778]

Good morning

[@koevidjinyaskoaugustine6778]

Good morning

[@kathyrunningcrane8519]

This video was AWESOME!!!! It has alot of Information, Nicely done.

[@RobertDIY]

Thanks for watching

[@TeknoSapien]

Very nice explanations on reading codes - thank you

[@RobertDIY]

Tekno Sapien Thanks for watching.

[@terrychappell802]

Hi Robert I have a 2001 Nissan Sentra we went to auto zone and they gave us a read out for the codes on my car. The two codes were P0304 and P0174. We replaced the all four of the spark plugs and cleaned the air-intake valves and the MAF sensor. My problem is that the car still is running rough. The RPM's on the car are running faster than the MPH's. It wont accelerate over 30 MPH and the RPM gauge goes well over 4000 or more when I give it gas. I don't know what else to check for on my car as far as it goes for making the car accelerate.

[@RobertDIY]

Terry King Check the codes again. Sounds like a transmission problem which will not show up on most scanners. You could also have a clogged catalysis converter.

[@AntonyEagle1994]

You mentioned to pour a little oil down the spark plug hole to test if the compression increases, are you referring to regular motor oil? Or what kind of oil? My cylinder two is misifiring

[@RobertDIY]

Regular motor oil.

[@RobertDIY]

kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@cmarvblacche8539]

I have a dodge charger 2008 and it feels like there is a miss fire with everything you said about the shaking when in idle. P306 was the code. Question is what should i be paying or estimate of this type job being done and should i have to replace all coils or injectors depending on the problem? I would appreciate it a bunch.

[@RobertDIY]

Cmarv BlacChe How many miles are on it? Has the spark plug ever been replaced? That code says that #6 cylinder is missing. So, I'd start with changing that plug, where ever it may be. Shops generally charge $90 per hour, even when changing 1 $8 spark plug. That may due it but if not, they have to progress down the troubleshooting trail. If you have a valve problem, it could cost you a LOT more than $98. - kzbin.info/www/bejne/iZiamnmvqd2ZsLM

[@garywithrow1912]

hey robert i have a 2001 chevy silverado 6.0 i have fire on all 8 the right side of the motor u can take off all the wires on the right side and it runs the same it a new motor new plugs and wires if that helps , smiley

[@RobertDIY]

Good deal. Thanks for posting back.