Trailblazer P0301, Is the coil bad

[@neilvergara463]

i own a 07 chevy blazer LS. diagnosed with the dreaded p0171 and the p0301. we basically changed/replaced the o2 sensor, spark plugs, coils, evap system, fuel filters, maf sensor, air filter, cleaned the throttle body and still the codes come up. it turned out its a leak on the intake manifold system. its hidden, not noticeable and a pain in the neck to get to, but once you replaced the gasket and tighten the bolts, you will appreciate your car better.

[@blackout260112]

Hello sir , I have a 2004 envoy, what gasket did you replace and what bolts did you tighten?

[@randallhighsmith2971]

I must admit that is one of the best troubleshooting videos I have ever seen,, it's out in field.. you're doing it while it happens, it's not any fixed scenario back in the shop or classroom step one step 2 bullshit.... I just wanted to say keep up the good work keep those videos coming if you can you are truly a professional and this is example how the real world works... I know of a example almost like this where this gentleman has spent a great amount of money at dealerships trying to find a engine Miss over something just about what you shared with us.. over a year-and-a-half in a 2002 Envoy this gentleman has been over $2,800 trying to get a engine Miss resolved... dealership told him it was injector issue, then of course he went through this coil plug issue... then I suddenly had a vacuum leak on intake problem.. then also we have a fuel low pressure problem.. then what finally done it they told him according to the compression check. the cylinder was lower in compression than the others by 5 PSI.. and it probably has maybe a broken ring a valve issue.. and they would have to start by pulling the head off.. and that's where he said enough is enough... and said the hell with it so I guess he drove it for a few more months with ignition Miss off and on. anyway one day in the parking lot at work I heard it running with a miss then a couple days later it's running fine. so I asked him about it he said he's tired of putting money into it and I asked him if he would want to sell it.... he told me the story tell him to throw a number out there he said 1000 k I said what about $500.00 he said no. and I said 650.00 final offer.. we shook hands came to a deal... after messing with it for about a week lucked out .. found power supply wire damaged right up where it goes into the plug... it was not completely broken there was was a few strands still in tact.. sometimes it would miss sometimes it wouldn't.. went to salvage yard found partial wiring harness just clipped the plug and about 5 inches of wire off of it got it spiced and installed a new plug in #6. cleared the codes and fired it up and ran good.. no miss no engine codes.. decided to go ahead and put it up for sale had it detailed it finally sold for $4000.. now that's pretty good little profit but it's a nice vehicle could have got a little bit more I think but oh well with the detail, a free coil plug and $7 spark plug there's no more than $80 into it and a little bit of my time

[@Britec09]

learn so much from these videos

[@rr3bro463]

Finally, great how to video. Get so irritated skimming through YT video after video To just get more irritated. Much appreciated my friend I SUB 👍

[@voodoogoddess29]

Very Helpful..thank you my 2003 trailblazer has the exact same code..so now I can go to a mechanic & know exactly what should be done..thanks

[@wtbm123]

Thanks for watching and commenting

[@CoquiAudio]

2:57 I use a small screw driver to remove those I just pick the bottom of the plastic clip, lift "carefully" then it remove the plug freely without using too much finger strength :)

[@wtbm123]

Thanks for watching and commenting

[@P-Dawg-01]

Great video! We are clinging on to our 2003 Trailblazer because it has been a great vehicle to us but also...we are still enjoying a period of time without a CAR PAYMENT! However, I just got done doing a few things to this car thinking I have fixed it but it still has a problem. Our major problem was the car stalling in the middle of a turn on my wife. Well that went over like a fart in church for my wife which lead me to removing the throttle body and cleaning that completely and reinstalling. Also replacing all the spark plugs and boots. It seemed to run a lot better after that but seemed to still have an idling issue here and there. Very sporadic where it seems to bog down and then is itself and returns to a normal idle. We then had an issue with it giving us a flow during non Purge error code and a check engine light that would not go away... Also caused difficulty in starting after a gas fill up. This caused me to first replace the gas cap which resulted in no change. Then I replaced one of two possible solenoids, the first being the easier of the two which was the purge canister valve down by the gas tank (if I am saying that right for its description). That also resulted in no change in the check engine light... so the next repair that I performed was the replacement of the purge valve solenoid which is installed on the engine block... This solved the flow during non-purge problem and eliminated the check engine light.... The problem I am having now that I wanted to ask you about is that it still has a, I guess you would call, an idling problem. It has done this a few times now....yesterday it hesitated where it shuddered/shook and dropped rpm really badly upon trying to take off and then jumped up to normal rpm and ran fine the rest of the drive. Has NOT stalled completely since I cleaned the throttle body but still has these occasional/intermittent instances of bogging down and acting like it is going to stall and then goes. Very frustrating and the wife is ready to throw in the towel on this car...but I just feel there is something I am missing that is very simple. Aside from a transmission fluid leak this car has been a very reliable everyday driver. Btw it has approx. 150k miles on it. I have given thought to pulling the throttle body back off and cleaning it again apparently there is an air hole or something that also needs to be cleaned out that they say also helps to control idle which I thought appeared to be clean and i did spray some throttle body cleaner into but I don't know if that flushed it out completely or if that could even be what is xausing my continuing rough idle issue. Any advice you could give me to save us a car payment would be greatly appreciated! Thanks in advance! Peter

[@wtbm123]

If cleaning it again does not fix it , and i take it the check engine light is not on , things just off the top of my head , Dirty or failing MAF , VVT Solenoid dirty sticking , Maybe a 02 sensor starting to fail , Could be quite a few things , is fuel pressure good . If not setting a light , really needs the live data watched to see what is acting up . Also possible vacuum leak , even a dirty fuel injector

[@robertvanderbaan3722]

Fuel injector cleaner

[@lakesideranch]

Good show Terry ! I like that scanner you have, tells all and user friendly too... Nice fix and great tutorial for the folks here ! Stay warm bnrother

[@wtbm123]

The scanner gives lots of info , you just got to know how to use it . Kinda a must if ya have to work on anything anymore. Thanks for watching Doug

[@joeklosowski8588]

Thank you for the clear and 2 the point instructions. Wish all videos were this straight forward. Could you make a video on this trailblazer and why the speakers are so sensitive to moisture and won't work for 2 days after rain?

[@wtbm123]

I was just working on it , so sorry it is not here .

[@ziggassedup]

I find that often I'll have to push the plug on tighter to release the clip..Gotta love when a gadget can steer you in the right direction..Good vid Terry...My rule of thumb is "change 1 plug...change 'em all"...But a good vid on how to..I was hoping you would show how to isolate a cylinder by disconnecting the coil trigger wires one at a time...The codes would still have to be cleared but..Good thing with a scanner is we can eliminate mechanical problems from electrical problems...I sometimes rely on the old fashioned experience before I run a scan....Sometimes I'm correct..!!...lol.

[@wtbm123]

I had a pretty good idea what it was going to be when i heard it run. The scanner showed me which cylinder ,so all i had to do was verify it was that coil. My rule of thumb is change as much bad stuff as the customer will pay for. But the plugs were changed not long before this so with no misfire counts after coil change i left them all in there. If plugs are older and a coil goes bad i suggest to customer to change all plugs ,because hi resistance on plugs can cause coil failure.

[@ziggassedup]

Exactly.

[@paulbaker5085]

I changed the plugs in mine and it had a misfire on # 5 cyl .When I bought the plugs at Napa there was a full box of four plugs and 2 singles .After examining the boxes one had a different barcode lot # same plug different lot .Cleaned my old plug replaced and it runs great .Always make sure the plug has the same barcode #. Not the first time this has happened

[@wtbm123]

I have never ran into that issue

[@TheShadeTreeFixitMan]

Very well explained process Terry. Thanks for sharing.

[@bridchvtruck568]

Good video thanks for bringing us along ended up doing all the inj. In my 5.3l took care of my codes see ya

[@wtbm123]

Thanks for watching

[@RodderFiles]

makes things alot ezier to have a code reader thats for sure, good video brotha

[@wtbm123]

StrtRodder100 Little more than a code reader but yes it sure makes live a lot easier.

[@angelisone]

I do not have that Snap On. What were the resistance measurements of the bad coil respect to a good coil? 1. Resistance measurements in circuit? 2. Resistance measurements out of circuit? 3. Resistance of rubber insulator (plastic post) to ground? Wonderful tips, thank you.

[@gregclatk8950]

Thank you so much very good video.and you did a good job explaining what you was doing.

[@wtbm123]

Thank you

[@sixtyfiveford]

Nicely done. Live data from the Snap-On scan tool is great.

[@wtbm123]

It comes in handy. Cost is hi but i use it almost every day so i guess it is worth it.

[@thelazycook5103]

@@wtbm123 i have a 2004 trailblazer it runs like it's gasping for gas and sometimes it stalled. We checked the sparkplugs and it's clean the mechanic said the coils is bad all of them are rusty.

[@fatstercat]

Good fix terry always like your how to vids I really like that snap on scanner take care buddy

[@wtbm123]

fatstercat Thanks Mark . Camaro looking good

[@tomdennis1622]

Thanks for this video. I did what you said and I was able to isolate a bad coil.

[@johnmarks7243]

That number one seems to be a issue with those, that ac line above drips water on them. I've even seen number one full of water and the rest are dry.damn 5 cylinders.

[@wtbm123]

Seems like i see 1 and 5 go out a lot on them . Oil leaking in is a big issue on them . Thanks for watching.

[@harvest38]

Take the airbox off, start the truck, unplug 1 coil at a time from front to back, the one that did not change engine idle is the bad one. no scanner needed, very common problem. if you own a trailblazer, keep a couple extra coils on hand.

[@wtbm123]

yes can swap coils to see

[@scottfirman]

I have an 03 TrailBlazer with over 200k. Havent had to do much to it till now,everything is starting to fail at once. I have always maintained it as far as oil changes,filters and other things. Being it has so many miles on it now,I am thinking its time to dump the old girl.

[@wtbm123]

Thanks for watching and commenting

[@timothyball3144]

Thank you for this. I have a friend three hours away that has a P0301 and I tried explaining it to her but this is better. At least now she knows what to expect when she takes it to a mechanic.

[@wtbm123]

Glad it helped

[@DR.Spexxy]

I know this is 8 years ago but I’m having this problem I replaced all the spark plugs and replaced the first coil thinking that be the problem unfortunately wasn’t what could be the issue

[@wtbm123]

Was there a p0301 code , Is that why the coil change on first cylinder . What codes or symptoms is there . Have you tested for spark or anything . If sure spark is good then i do an injector balance test . and if spark and injector test is ok and passes then i do a compression check on a few cylinders to compare

[@DR.Spexxy]

@@wtbm123 I just went ahead and replaced the spark plugs and I had a p0301 code so I just changed coil pack in the first one anyway I heard it’s many different things it started rough idling on July 4th

[@DR.Spexxy]

@@wtbm123 definitely need to do injector test

[@wtbm123]

@@DR.Spexxy Do you feel a miss under acceleration or just at idle . Do you have a scanner or know anyone with one , That does live data.

[@DR.Spexxy]

@@wtbm123 that u don’t know of anyone m top of my head tbh I have to ask my father if he does but I’m getting it through idle

[@SteveRobReviews]

Well done - it gets real interesting when the fault doesn't move and a new plug and coil doesn't fix it either. Every time I work on a farm truck not used all the time the first thing I check is for mice damage. I was working on one yesterday and after the poor old guy replaced two alternators he goes to the local garage and they charge him $60 to tell him this new alternator is defective as well . I had to rewire a whole new harness to the alternator. All but a couple of strands of wire were left and of course you would see the correct voltage but you couldn't even light a test light. Do you see mice damage down your way ?

[@wtbm123]

Steve Rob Yes , there are a lot of farms around and the farm trucks and tractors that do not get driven get mice in them . What they do not chew they piss on. If you throw cotton balls in them or on tractors close to wiring with peppermint oil on them it will keep a lot of mice out if not all.

[@SteveRobReviews]

That's a great tip I have never heard before I will try it out on my machinery and pass it on to others. Thanks.

[@TimsComputerRepair]

Good troubleshooting Terry,

[@popiwatv]

thank you for this video, and also the walkthrough on it. big help

[@wtbm123]

Thanks for stopping by and commenting

[@zx8401ztv]

Smashing video :-)) Thats one dusty/mucky engine, the new coil pack makes the others look really filthy. The obd tool is a must isnt it, snapon isnt cheap but im sure its capabilitys in comparison to cheaper units make it indispensible :-) I would be looking at the sparkplug tip colour and hoping i could see which one was different, but the odd annoying misfire i suspect would not fowl up the plug good enough for a visual diagnosis.

[@wtbm123]

Could use a code reader in this case , and moving coil would set a new different code. There are a few good scanners out there , but Snap-On seems to be the most expensive , but i use it almost every day so it makes one feel better about the cost.

[@ProjectCarTV]

nice

[@wtbm123]

Thanks

[@BONEFORLYFE]

Just did A spark plug job it started up fine with the new plugs but misfiring so I decided to put the old ones back in because I figured the new ones were faulty. So I put the old ones I and now it's crank no start? WTF JUST FROM PUTTING INTHE OLD PLUGS. So I then took out the old ones and put the new ones back just to get it started and it's still NO CRANK NO START.

[@wtbm123]

did you unplug anything , are coils plugged in . Have you checked for spark

[@BONEFORLYFE]

@@wtbm123 yes. Yes and yes. These is spark. Brand new coils brand new spark plugs

[@demarques1911]

I let my truck run and I unplugged the ignition coil wire #3 and the truck didn't miss... But the other coil wires... It missed when I unplug them .. I think the ignition wire needs to be replaced... I might get another harness or splice some wires from the other trailblazer I have setting up

[@wtbm123]

It could be wiring , if moving coils around did not do anything

[@demarques1911]

@@wtbm123 I'm going to listen to the coils with a screwdriver this weekend...the check engine light is blinking now🙄

[@JohnCarey1963Jag]

Good fix Terry. thanks.

[@davidkim690]

Hi, I had one question: how do you remove the white clip that holds down the plastic wire tray? Do you pry it up or does it turn counterclockwise like a screw? Also it was a great video, nice work. Thanks.

[@wtbm123]

I just put a screwdriver under the black plastic close to clip and pry it up out . Thanks for watching and commenting.

[@AntLive29]

Great video. Very helpful

[@MyMASON007]

Hey I'm having the same problem each time i turn the truck on it rattles. Its good for about 5 miles but once i come to a stop, the truck shuts off. I replaced the spark plugs to 4 out of 6 and its still has the same problem. Im waiting for new coils to come in. Once I replace them I'll post the finding. Thanks for the video.

[@wtbm123]

Hope that solves the issue . Thanks for watching and commenting

[@abrahamvaro5482]

Very nice video thanks!!!

[@wtbm123]

Glad you liked it!

[@jomoral17]

Firing order 153624.... Is that not #5 you unplug at 6:26

[@ruby_and_sapphire_official]

Just to be clear. The #1plug is in the back, 4 is in the front

[@wtbm123]

My book says #1 is up front

[@OldSkoolF]

Oil in the plug holes is caused by loose coil pack bolts...

[@wtbm123]

no bad valve cover gasket

[@josiegorden6973]

I know this is an older video but thank you, regardless.. How do I know if my boot is nad on my coil pack?

[@wtbm123]

Rubber split , spring inside corroded . They do not cost much if any are doubtful then i just replace them.

[@rr3bro463]

My 07 Envoy 4.2 has p0300 and p0306. Has150k so I Changed plugs and came across #3 wet with oil and oily plug. Was able to clean out with detail attachment on shop vac. Don’t have scan tool so will run and use parts stores to reset codes. If theirs oil on my plug it’s bad head gasket. Is it okay to drive with it leaking & or can it cause other damage? Awesome video

[@wtbm123]

Valve cover gasket . It is not much for the gasket , but takes quite some time to install . If not leaking bad then can keep it cleaned out . Oil in there will eventually cause a misfire . and can hurt a coil . . Some take a long time to fill the spark plug wells with oil , just depends on how bad it leaks

[@timothyfritsch8801]

when in went into these soft grassy slippery hills it was a hiccup as its powerless now wont idle cannot get back up on its own wich in turn in a rural setting would make it useless maybe a kinda safari SUV still it has yet to show dependability -so boss says it comes out on own power or else hee haw been down there 3 weeks

[@snocrushr]

That scan tool sure takes the guess work out of it.

[@wtbm123]

Yea but want a scope next

[@timothyfritsch8801]

me alsoi t was darn near perfect thanks im working or helping on a similar SUV stuck in the fields oh boy

[@rickjames1179]

Should i lube it up or no ? With the lube they give for the condensation

[@wtbm123]

Dielectric greas is good for top of spark plug connection .

[@devinhutson3977]

I have same make and model trailblazer went changes plugs cause just bought couple months ago been running fine noticed wire on very back plug was unhooked lose plugged back up ride will crank won't start please help

[@wtbm123]

Not sure with out seeing it , have you tested to see if you lost spark

[@johnw4985]

Great video for explaining how to check to be sure, thanks, what should a GM coil cost ? my guy says $240, sound high, what do u think, thanks

[@wtbm123]

+JOHN WEITZMAN Just to buy the coil , i believe is $50 - $100 dollars depending on where u get it , but that would be for the coil , diagnostic and replacement cost would also be added . I check spark plugs when i do them usually , as worn plugs can lead to bad coils

[@johnw4985]

+wtbm123 Thanks so much. Taking it in tomorrow. Will call Chevy for cost and override my guy. He said 240$ plus 60$ to change. But your video was great for questions to ask. Plugs have never been changed 75'000 miles

[@johnw4985]

+wtbm123 Thanks for your help, this video helped me big time. I tried myself PO303 code and changed all 6 plugs, The coil was expensive, $200 genuine GM, I could have got a third party for under $100 online but did not want to wait. GM online was about $150 . Once I changed everything and reset code. I still got a PO303. I got so frustrated I took it back to my guy who cleaned everything and started changing coils, then we got a PO300, Turns out after 3 hours of changing and cleaning everything along with checking wires we found 4 was bad as well. .If I could upload pics I would show you that 4 was totally burnt and 3 the one I got the code for did not look bad, like the other 4 coils..Go figure ..Thanks for the video help , will look for your videos for future issues..

[@wtbm123]

+JOHN WEITZMAN Some diagnostic scanners , you can get in and see live misfire data for each cylinder . easy then to spot the bad ones , but those are pricey . Prob the least priced scanner , i know of with live data and bi directional tools is the autel max das 708 .

[@wtbm123]

+wtbm123 a cylinder has to misfire so many times in so many fires to set a specific cyl code , just under that number just sets a random po3000

[@rosaazul88]

So if it were the 4th one (p0304 code) would i switch to the first to test or 3rd?

[@wtbm123]

Just switch one you think is bad to any cylinder that is good to see if issue follows that coil

[@MACTFordEdge]

My 2004 Trailblazer had a misfire on #4. I replaced the plugs and the #4 coil. The issue is now I have multiple misfires with a flashing check engine light. I sprayed the throttle body and wipe it off/out best I could and this did nothing. The trailblazer seems to be running on about 4 cylinders. Any advice on what else to check. The truck is simply unusable at this point and I would like to get it running without spending money for chasing ghosts. Could the cam be bad? the mileage is 110,000 Plugs are OEM replacements. New coil is autozone branded OEM replacement. Autozone say maybe the new coil is causing the other ones to not work right, but I feel this is a sales pitch how could multiple coils fail by replacing one coil

[@wtbm123]

If read #4 misfire off a code reader , then the other cylinders may of been misfiring too . If cylinders misfire enough it sets a code for that cylinder , but if misfire is detected but not enough misses to pinpoint one cylinder then it reports a random misfire, and both can happen at same time . Does it run better or worse if rpms are raised . does it start easy . This could be a lot of things , may not be a spark issue . Is oil changed regularly and full.. There is a VVT solenoid that can cause cam timing issues if bad, or screens clogged due to being plugged . Also have you done a fuel pressure check , is there a vacuum leak , air cleaner plugged or dirty . Is the cat converter working or plugged . A lot of things come to mind , but the best way is to have it hooked to a scan tool that can give more than just codes. Then one could see the misfire counts for each cylinder in real time, the fuel trims, o2 readings and be able to figure out what is going on with out replacing a lot of parts. Autozone only uses a code reader , so they can only guess most of the time .

[@MACTFordEdge]

I have access to a realtime code reader and assistance of a trained mechanic so I guess I will have to go this route to drill deeper into the issue.

[@juanlatin3595]

MACTFORDEDGE did u ever resolve the problem

[@FireEater]

Short and sweet thanks.👍🏻

[@wtbm123]

+Mike Blake Thank you

[@Trakehner20]

I switched 3&4 coils out, and it went from 3 to 4 for misfire. So do you think that while I'm in there, I should just go ahead and change everything, plugs and coils, to not have to worry about it anymore? And are the cheaper coils on Amazon worth using, or should I get the Delphi coils that are meant for GM? I.ines an 03 trailblazer.

[@wtbm123]

I would change the spark plugs , old plugs is sometimes what takes coils out . If replacing with quality coils then ok , if replacing with Cheap coils , then your old coils may last just as long .

[@TheRon1943]

Had same problem with my 2004 Envoy. Turns out it had an oil leak into #4. Fouled the plug and shorted out the coil. Mechanic said it would be $500 to replace the valve cover gasket. Gasket only $28. Because you have to remove so much off the top, lots of time. Any way to seal around that socket to keep oil out?

[@wtbm123]

The oil leaking in the spark plug wells is a common problem on those . Some leak fast and some take quiet some time to fill up the well . I know people who take a rag and get the oil out of well . They do this , then go again for a bit , and do it again . It is a time consuming job to change the gasket , but is the only real fix

[@TheRon1943]

On another site the mechanic uses RTV slicone around the socket, to keep oil from getting down to the plug.

[@meanf1502]

What about a random misfire 06 trailblazer did the plugs did the vvt

[@wtbm123]

Could be a lot of things , may check fuel pressure , or a injector balance test , check for vacuum leak , and things like that

[@jakebarrett2339]

Ya don't need to put it back on or any of that...just start disconnecting one coil at a time...if the idle doesn't change then the coil is bad.

[@wtbm123]

Not really as it could be a spark plug or wiring to the coil and you would not know until after you bought new parts

[@jakebarrett2339]

That's True, I took mine to O'Reilly and it didn't even throw a code...I just started unplugging them and found that one. Up and running!

[@gregmcnair6935]

No Doubt mine is fuel issue specially running out of gas where do I stand ?

[@wtbm123]

Start with fuel pressure test if thinking fuel , if that is ok then maybe a injector balance test

[@johnw4985]

another question for you, I have the Launch Creader VI code reader, would you recommend anything else or is this reader fine? It gave me this issue PO303 and when I had my secondary emissions issue code PO410, just wondering if I should get another, my shop guy uses this and another as backup !

[@wtbm123]

+JOHN WEITZMAN Well depending on how much work going to do . . i at minimum would want live data as just a code reader tells what alerted the code but many times only is the alerter and not the issue. Then to do alot of work you will end up needing bi directional tools. and access to body control , abs, and other systems. I myself use a snap on solus ultra , but also around $4,000, and there are still much better ones out there , but even more money

[@jacobstory8103]

Had this same problem on my 03 Trailblazer. Did what you suggested, switched two of the coils around. It seems to be running better but now I am getting the general misfire code P300. A friend suggested changing the coil packs in order of the firing sequence. What would you suggest I look at next?

[@wtbm123]

+Jacob Story If both coils are good switching them should not make a difference . The idea in switching is to see if miss follows indicating a bad coil . Was it a code for a specific cylinder before . If not a dead coil that followed with cylinders when switching then , may look else where , spark plugs, wires or boots , is there oil around the spark plugs . May look for a vacuum leak . Be nice to hook up a scanner to see what cylinder is doing it and the fuel trims . Usually but not always , a coil will make a dead miss .

[@morgansparhawk8410]

I just had to have a coil replaced in my 2004 trailblazer. Not sure which cylinder it was

[@fmjjr3672]

Morgan Sparhawk quick question was your service light flashing and did your cruise control not work?

[@morgansparhawk8410]

@@fmjjr3672 exactly

[@fmjjr3672]

Morgan Sparhawk thanks. It’s running pretty rough so I hope it’s just one

[@fmjjr3672]

Morgan Sparhawk yessir you were right cylinder 4 is miss firing changed all spark plugs and connected super chip to confirm

[@morgansparhawk8410]

@@fmjjr3672 cool. I'm a woman tho lol. Cost me 163$ parts and labor. I don't know my way around under the hood of anything much past 1980 😒

[@albatroz27]

Hey I've a question...and I'm trying to determine why my 2002 trailblazer is not starting up. I've tested all coils one by one and initially only two were sparking after some more testing, now none is sparking but they all have power going to them. But my question is: how many ohms should a new coil test for A B and C wires? Thank you

[@wtbm123]

Not sure on the oms for yours , but if power going to them is the computer controlling them . odd to think all but two went bad at same time then two more . maybe a wire connection , , does the crank sensor signal look good

[@albatroz27]

wtbm123 Sorry about not replying to your answer sooner, but I couldn't figure out how to find comments I've made on KZbin because they've removed that feature. So I finally figured out in my emails where to find them. The crank sensor signal is good because I don't see any codes coming up in my scanner for any sensor. I'm gonna try new spark plugs. That's my last effort. thank you man.

[@jamesmullins7413]

Good video,I also got an P0301 on my 05 Trailblazer and I did swap out 1 in number two's place and erased the code but for some reason instead of the code P0302 coming up I got P0300 instead why do you think that happened?,I even changed the plug with a new one of the same type.

[@wtbm123]

Yea sometimes it is hard if you do not have a scanner capable of watching the misfire counts on all cylinders . Changing the plugs may of been why . You may have a weak coil and still able to throw a halfway good spark on a good plug . There is a counter that keeps repeating every 200 revolutions and if it sees enough misfires on one cylinder after so many revolutions it will trigger a code for that cylinder . If it misfires but not enough on any one cylinder to trigger a cylinder it will show as a random code , A random can be more than one cylinder or just not enough misses in x amount of revolutions to trigger a cylinder number code . So if the number one cylinder did not set a p0301 it could still be that coil. , If that makes any sense

[@jamesmullins7413]

@@wtbm123 Thanks for getting back,but when I put the new coil into the number 1 position I then got the P0302 code and then when I switched out the number 2 coil with the good one,no code and it ran like a dream.

[@jamesmullins7413]

@@wtbm123 Hi I'am just seeing this and thank you for your response but with in my situation when the plug is soaked with oil there's always been to senarios that been at faulteither a bad oil ring or as I've heard in this case a bad valve pan gasket and we all know that when oild drowns out a plug it's not going to fire like it once did therefore perhaps causing the misfire code to show up.

[@K1NGPUFF]

The dude who replied to you was correct. You gotta drive enough for the system to figure out which cylinder. P0300 is unspecified. Mines turned into p0301 (x2). I had a P0173 but fixed it with a new o2 sensor. Still have a misfire, finna check the coil....

[@monmixer]

thanks for the vid, mine is misfire on 3 so it will be easier. lol

[@wtbm123]

Thanks for watching and commenting

[@christinah-m468]

I had a p0302. I swapped coil number 2 and 3. Now when I check it it's giving me the random p0300. Any ideas?

[@wtbm123]

Did you change the spark plugs . A weak coil can sometimes work well enough for a good spark plug . but after run with a weak coil dirty up the spark plug . Also worn spark plugs can over heat a coil and make it go bad . I suspect if ran for a while the po3003 will show . . the computer counts how many misfires in a cycle and if enough on one cylinder it set a code for the cylinder . if missing but not enough times to set code for a cylinder it will come up as random .

[@brianmulholland1698]

What would cause coil pack#1cyl to fail repetitively? on third pack 2nd spark plug. Thanks.

[@wtbm123]

Some times cheap coils can fail quickly . Is all the wiring good

[@bjenks2]

@wtbm123 I have a 2005 trailblazer and it's a project car. when I bought it it had codes for pcm, misfire on cylinder 3, vss and fuel level sensor. I fixed most of them by cleaning the throttle body and tightening the loose ground on the drivers side fender. Now the car he a slight misfire on cylinder 3. I bought a new plug and swapped the coil and the cylinder is still dead. Also my obd2 port isn't responding but it has power. The cigar fuse is good too. I could care less about the fuel level sensor just need to get ride rid of this slight misfire. Any suggestions?

[@jaimesustaita285]

Which brand of coil would u recommend,rock auto sells different brands and prices,I'd hate to order one coil just to find out it doesn't fit!!

[@wtbm123]

I am not a Rock Auto fan , but i mostly would just not get the cheapest no mane one . Most mid priced ones should be ok.

[@jaimesustaita285]

Ok, thk-u for your quick reply!!

[@stevestevenson289]

Does the service engine light blink?

[@wtbm123]

When it blinks , a lot of times it will be because of a misfire. A check engine light lit up is a code , Blinking means if continue driving it could damage the cat converter

[@XMyatery]

how do you take out the boot/ cords? we did what you said and #1 still misfires.

[@wtbm123]

If you have a misfire on cylinder one , i would un plug its wire connector and switch that coil and plug boot with one from a different cylinder . If the coil that was on number 1 cylinder is moved to a different cylinder and misfire does not follow but stays misfiring on number 1 then the coil is ok . if number 1 is still misfiring after coil swap , then could pull spark plug and check . Oh and if oil is up around spark plug , the valve cover is leaking and the oil could make the miss. Could check to see number 1 coil is firing with a spark tester . If no spark then may need to look into the wiring going to coil . If have spark , then can move to test either compression , to verify cylinder is not low on compression compared to a known good cylinder with out a misfire . if compression is good , has spark on misfiring cylinder then i would test fuel injectors .

[@alvarosoto541]

Hello, I have been working on my 2002 Trailblazer code P0301 misfiring cylinder #1. I've replaced the ignition coil but the problem hasn't resolved. What other problem could it have? I would greatly appreciate if you could give me an idea of what other problems it might have. Thank you.

[@wtbm123]

did u check the spark plug . is there oil around it , if so the oil may be it. does that cylinder have spark or no spark . if no spark and if swapping coils did not make spark , then is there power and control at the coil . if spark , then move to compression and then fuel .

[@alvarosoto541]

Thank you for your reply. I have replaced all 6 spark plugs and found oil on ignition coil #4 and the old spark plug was covered with oil. I replaced ignition coil #4 with a new coil and swapped it with coil #1 and still had the problem. Thank you for your time and for your reply.

[@wtbm123]

Have you seen spark from #1 coil at all . If there is spark at coil then , i would check compression and fuel .

[@alvarosoto541]

No I have not seen spark from coil #1. I disconnected the connector from coil #1 and it didn't show any difference when running motor but with the other 5 coils if I disconnect one you can hear a difference on the motor. Thank you and sorry to keep bothering but your video was very helpful.

[@MEXICANVATO69XP]

My trailblazer has cylinder 6 misfire which makes the truck jerk and i changed the spark plugs but the check engine light is still on. Do I have to erase it or do i need to fix something else?

[@johnmuller5403]

A new coil WILL fixed this miss in the Trailblazer. cylinder 6 is the cylinder at the firewall. That will fix your problem! FOR SURE!!! Let me know if it worked? P.S. Dont buy that coil pack at a auto parts store! You can buy it online for 15$ OR all 6 of them for $59.99. OR go to a junk yard & pay 10$ for it! I hope i helped! I have a 2004 Trailblazer and my wife has the 2004 ENVOY. I know what i'm talking about. If it's running fine now after the plug now, then you should wait a few days & the light should come off!

[@MEXICANVATO69XP]

John Muller We bought the coil and we put it already but my uncle tighten it to tight and broke the screw that holds the coil in place. Do I need to drill out the piece of screw and then use a kit to fix the threads?

[@johnmuller5403]

No, just tighten it the best you can will do fine. They are sucktioned on the spark plug & wont be a big deal!

[@sacariovincente]

I have a 2004 trailblazer lt 4.2 i had a misfire on cylinder one....i had the coil pack changed started it up still running rough like yours was but got it scanned again misfire cylinder 2🤔🤔🤔🤔 what are your thoughts plz help mechanic says i should change the other 5 and get a tune up? Wat u think? Thank u

[@johnmuller5403]

If you're due for plugs? I would do a tune up too!! And take off the throttlbody & clean that too!!!

[@joser.2396]

I have p0301 , so I switched coil to cylinder # 2& now it reads p0300 , any thoughts . Engine is really shaky 🤔

[@wtbm123]

Drive it a few min and see if it gives a p0302 . could check coil for spark . did you look at the spark plug

[@joser.2396]

wtbm123 I found it , it was a coil thank you 🙏🏻

[@natestaverman451]

Jose R. Did you reset the computer could disconnect the battery for at least 10 minutes to do that if you don't have a scan tool to do it plus if there is any oil at all it will still randomly misfire which is the 300 code

[@joser.2396]

nate staverman thank you it was a coil . Yes I had also done that, thank you for replying.

[@ruscardin6255]

I have a Chevy trailblazer 2005 I have a code p301 and I change spark plugs but I find oil on spark plugs What could be the problem Help please Thank you in advance

[@wtbm123]

Oil is from the valve cover leaking .

[@davidhampton3760]

If I have oil in inside the coil with the spark plug what kind of problem do I have

[@wtbm123]

leaky valve cover gasket , but time consuming job on these

[@peterenriquez8684]

How to tack a scur if you burak the scur

[@peterenriquez8684]

When changeing sparplugs

[@wtbm123]

Thanks for watching and commenting

[@tomswonderfulworld]

I like this kind

[@wtbm123]

Thanks Tom

[@coreyl736]

A lot of times u will find oil draining on plugs get ya some engine puty spread around seal

[@wtbm123]

Thanks for watching

[@jamesheidelberg8990]

Have a 2003 envoy 4.2 that keeps giving a cylinder one misfire. I've changed the out with three good coils and changed the spark plug everytime as well. Still getting the cylinder one misfire. Any other suggestions?

[@wtbm123]

may look into the fuel system . maybe a injector

[@paperweightgirl]

Not sure what you were doing, but it was interesting. ;0)

[@wtbm123]

Thank you . Were u exercising while u watched . lol

[@paperweightgirl]

Did my exercises for the day already, now it's time to relax. lol

[@darrellpurnell2181]

great video ...trains comming

[@wtbm123]

Thanks for stopping by and commenting

[@j3rs3yjak3FIU]

Really helpful!

[@wtbm123]

Thanks for stopping by

[@RobsPackanShine]

nice fix

[@ruby_and_sapphire_official]

Front to back is #4.3.6.2.5.1

[@kg7yts187]

Well... In my car I swapped 5&6 and got a misfire in cylinder 1

[@wtbm123]

Where was the misfire before . What do the spark plugs look like as old plugs are hard on coils

[@kg7yts187]

@@wtbm123 the misfire was in 6… but turns out it was a bad 1 coil pack… not sure why the 6 misfired because it fixed itself… brand new plugs at the time

[@sargken1]

What kinda scanner is that?

[@wtbm123]

snap on solus ultra

[@Timetotinker]

very cool........tony

[@wtbm123]

Timetotinker Thanks

[@superherobusinessacademy5679]

Where did you get a 5 cylinder Trailblazer? Ha!

[@wtbm123]

lol

[@CHOPSHOPUNDERGROUND]

My wife's car is the same thing, same thing happened to her's And I did the same thing but I also changed the plugs,And let me tell you that last coil and plug was a pain in the @ss to change.

[@wtbm123]

CHOPSHOPUNDERGROUND Someone supposedly had changed these plugs not long before so i left them in , but a lot of times if plugs get used up they can lead to coil failure . Try doing the valve cover , yours might not leak now but it more than likely will. I do not see many that do not have oil in at least one plug hole.

[@adrianamorales818]

CHOPSHOPUNDERGROUND yea,i changed ...well,my husband,changed out my spark plugs...they were decent,except the last two in the back,they were rusted,its s shaking...I imagine e to need to change out the plugs qnd coils,hows your the truck running now???

[@justmyopinion5234]

Mine turned out to be zero comprehension on 3

[@wtbm123]

Yes that can happen . Thanks for sharing , it could help others in the future

[@justmyopinion5234]

@@wtbm123 Now I'm going to see how long it will continue to run like this. Right after I install a new fuel pump and filter

[@michaelrodenberg643]

A good mechanic would have at least pulled the cylinder 1 plug and inspected it, the number one cause of failed ignition coils is worn spark plugs, and you put an old coil on top of the plug that was not firing, it's OK for diagnostic purposes but I wouldn't have shipped the vehicle like that, that's just asking for a comeback.

[@wtbm123]

Thanks for watching and commenting

[@CountrySideClub]

Cool

[@wtbm123]

Thanks.

[@may03LT]

I'm no coilologist but according to facebook it might be bad

[@wtbm123]

Thanks for stopping by and commenting

[@DougHinVA]

For my 2000 Corolla, a set of 4 coils was hardly $100 and a set of 4 platinum plugs was $30. And the savings over a garage doing it easily was $200-250. Do the basic stuff for yourself.

[@wtbm123]

Thanks for watching and commenting

[@josephlagorio3652]

Ford trailblazer really bro, wtf. That is what i heard! Lmfao

[@wtbm123]

Thanks for watching

[@PeeterPuncher]

Often times it ends up being worn out valves/seats and needs a valve job....and good luck getting the head off without the head bolts breaking off in the block. Junk ass GM.

[@TheShadeTreeFixitMan]

Very well explained process Terry. Thanks for sharing.

[@Nobody-sp9xj]

Great video, very helpful

[@wtbm123]

Glad it helped . Thanks for stopping in and commenting