Fixing a Jeep P0303 misfire

[@OzMechanics]

**Want to own the tools I use ?? Click on the amazon link below to get my top 5 Tools I use** Automotive Test Light- amzn.to/3z1Pdxa Flexible Backprobe- amzn.to/3Pyr3zO Multimeter- amzn.to/3PbuT23 OBD Scan Tool- amzn.to/3zaNWnq Wire Piercing Probe- amzn.to/3OecWhT

[@mattnewby123]

SOAK NEW LIFTERS IN OIL FOR A WHILE....

[@leecorkish5838]

Hello OZ, My son is yet another happy (college student) car owner thanks to this video. P0303 code. He replaced all coils and spark plugs. Result Same code. Took it to a dealership waited 4 weeks, they could not fix the problem, Didn't charge him. they drove it to him. He took it to another shop, they could not find a code and would not do anything. I told him to watch your video. He told the next garage to check for compression and a rocker arm problem and the P0303 code popped again. They found the rocker arm off and plus a couple of other issues with the valve cover. It's now fixed!!! thank you Sometimes I think people today don't take enough time to evaluate a problem if it is not apparent what the problem is. And rely on technology too much to tell them the issue... I highly recommend this video if your having these issues.

[@OzMechanics]

Awesome to hear this video helped out Lee. Thanks for stopping by

[@ena-heraki-minio]

After having read / watched half of the internet trying to diagnose my 3.7 kj missfires I landed onto this gem. You sir are a legend. Thanks :)

[@howie2092]

Same exact problem on my neighbor's jeep. 2 mechanics failed to diagnose it. One recommended a new engine. I fixed it for $40 using your excellent video. Thank you sir!

[@jeffcuevas5728]

HOLY CRAP!!! I just had a jeep in for the same issue... went to four shops no fix.... its in my bay NOW! lol.... I feel like a super hero! THanks BRO! Im all over it!! BIG ASS SUB!!!!

[@OzMechanics]

Saaaaaweeeeeeeeeet glad this video helped out. Thanks for stopping by and watching

[@8power0]

THANKS I LIKE HOW YOU EXPLAIN THE DIAGNOSIS , IT MAKES IT MUCH EASIER TO UNDERSTAND WE ALL THANK YOU HERE AND WILL BE WAITING TO SEE MORE VIDEOS THANKS !

[@ReaIHuman]

Sadly I had a misfire on my jeep earlier today, glad this video exists.

[@eddiecantu1064]

I had a misfire on cylinder #2. I was hoping that all I had to do was change the spark plugs and ignition coils. If it wasn’t for this video I probably would have taken this to someone and paid more than I could right now. I opened her up and boom there was a rocker laying at the bottom. Replaced both the lifter and the rocker. Running great now. Thank you.

[@mrwhamisrick]

Was your misfire all the time or only under a load? I'm having a cylinder 2 misfire but it's only while accelerating hard up to highway speed of pulling. trailer when the RPMs stay higher longer while accelerating.

[@johndavidmcdowell3269]

Having a similar issue with my 2005 Jeep Liberty. Have an appt on monday but thanks to you I'm gonna check my rocker arms this weekend. You sir may have just saved me a couple hundred dollars. Thanks man. Will post back with an update.

[@Diagnosedan]

Very proffesional approach, you made great use of your tools. And not only did you diagnose and fix the problem but also confirmed the fix. I loved it, thanks for the video!

[@OzMechanics]

If you feel like this video helped out, feel free to support the channel by donating. Just one click away on the link below, to help support the channel :) www.paypal.me/ozmechanics

[@DontTreadOnMe-ig3pc]

If something like that were to happen on the 4.7 will it make it smoke out of that exhaust I have a 99 Jeep grand Cherokee and it was smoke when you first start it up pretty bad blue smoke and then once it warms up it stops if you’re driving but as soon as you let it idle for a little bit and then hit a gas real hard it blows out a huge cloud of blue smoke

[@SuperMarioDiagnostics]

Nicely done, having a bit of product knowledge sure helps to pinpoint the fault quicker 👍👍👍

[@sandyande]

Cheers Oz, never an overkill, great to see different diagnostic techniques, thanks again, Sandy

[@fatherguidosarduchi5204]

I found this video refreshing. Finally a real mechanic. The dealerships have trained techs. They only learn from books without much hands on. Good mechanics cross train on everything and need to know how to read the engine and vehicle systems. Dealership techs just roll parts onto the car until it runs correctly again. This man knows his stuff and I’m so glad to see someone like him out there. Question for him though. Do you or have you gone to the smaller hole rockers that Chrysler updated for these engines? They did this to help remedy the rocker from rolling out of position when the lifter collapses or breaks an internal spring. Lots of times when the rockers rolls out the lifter does also and can wreak havoc with the valve train.

[@wyattoneable]

Nice use of the PICO before and after. First to find a direction and second to verify the fix.

[@OzMechanics]

Thanks for stopping by

[@rosabellebracke356]

How much should I pay for this repair? In florida

[@jameswasher3938]

Thanks. I'm going out tomorrow morning to check out one of these engines. I fear it's the valve seat issue more than the lifter, but, the in-cylinder as you showed with help make that distinction

[@wagoosh78]

I learned something new today thank you

[@gs7865]

I think without that experience knowing that motor throws lifters, a lot of us would chase a dozen other things before figuring that out. Nice work, thanks for your vids.

[@FourbrrlGrabber]

You should see the pressure wave when the intake valve doesn’t open..😁 Before pressure transducers.. scope would show very low spark kv, long burn time, pulled plug, covered in fresh oil from vacuum pulling oil past the rings ..

[@dennisdaugherty1314]

Thanks Oz I have the same problem and now I know how to fix it, and my lifter went through valve cover and I'm going to try and put the broken piece back in using JB plastic weld I'm hoping it work's a new one is almost 200 buck's. I'll let you know how it turns out and thank you for this video, I don't have a scope so I'm keeping my fingers crossed

[@Ako-John]

4 year old video, and saved my '12 Liberty , thank you sir, and i subscribed👍

[@jimthecarguy]

Nice diagnoses and repair. Hope everything is going ok for you with this heat.

[@OzMechanics]

Thanks for stopping by Jim. It’s nice and cool here in Texas only in the upper 90’s

[@hgbboosting8307]

Always have to wonder why people thumbs down a good video. I guess the pico scope was a turn off to them and they wanted to also see an actual compression gauge at work in comparison. The man is not perfect, no one is, but took the time to make the video for those interested. Thanks for the video sir, it helped many people vs the few that would criticize.

[@briankeltsch8932]

Fantastic. Helping my bro with some old school methodology. Great tip on the pedal down start. (We were ready to disconnect fuel relay.) We did all the previous (coil/plug/even injectors, and 303 persisted. Was ready to check compression and inspect the cylinder with a scope. Thought there may be some carbon or foreign object in the valve seat. I had no idea the rocker could just "fall off." Wild. Back in the day, you just had to tighten them up some. You have a new follower! Thanks again. Hopefully we got it.

[@CravinMorehead420]

Nice. Worked on a few 4.7l with broken coils and a few with stuck lifters and missing rockers. Haven't bought a PICO scope (yet), but clear flood and scanner helped me find the bad cylinder(s). Appreciate your videos..

[@OzMechanics]

If you ever get the pico you will love it. One of my best investments

[@robertdoran7387]

Liked and Subscribed. Hard to find knowledgeable mechanics on KZbin. Guys like you have spent the money (I saw that Snap-on scan tool, dude) and put in the time to be called professional. Good information. Concise. Well done.

[@OzMechanics]

Thanks for the kind words brother.

[@shaunbernier3672]

I have the 4.7 Dakota. And I have the same misfire. I changed plugs,coils and injectors. I think this is going to be my fix. Thanks 👍

[@mauricioespinoza5390]

Great video, could you do more videos like this on how to analyze graphs I thought that edit in the video was great showing the intake compression power and exhaust stroke.

[@VoltageDropDiagnostics]

Great one Oz. I was over here nerding out!

[@reynaldosolorzano9359]

You Rock…had similar problem you helped me out a lot.

[@OzMechanics]

Awesome Reynaldo!!! Glad this video guide you to the repair

[@fire7765]

The power of knowledge.

[@pabloloera6460]

You are a good mechanic keep up the good work Buddy😀

[@OzMechanics]

Thank you very much for the kind words

[@afterhoursfab]

Awesome info here. Just got a 3.7L in as a project with a bad miss on #4, def going to check this out.

[@DKG505]

Very helpful video ! Dealing with the same problem right now and it brought me here thanks! New coils New plugs Same problem! 🤷‍♂️ I guess I’ll go under cover for this one ☝️ Pun intended

[@Caeser194]

I'm having the same issue,tearing into it today,thanks for the video

[@everydaynine_2282]

did it work?

[@CubasAutomotive]

Buenísimo! Nice usage of the scope. 👍👍

[@billrimmer5596]

Dang, that was a super video and fix. Made it seem simple. A good teacher makes a complicated subject seem simple!!

[@OzMechanics]

Thanks for the kind words. And thanks for stopping by

[@t243jodie1]

Great vid bro, I got a misfire in my GC I did the coil, no change but I'm gonna do the plug next. never thought to listen for the cadence though to see if the rocker fell out. I actually didn't know this was a problem! Thanks for what you do. Cheers!

[@lstruggy]

New sub nice video sir 🤙🏽 I’ve recently replaced my 90d elbows of my pcv hoses cause the oem ones are old brittle cracked from p0507 code, the old ones were hard plastic the new ones were softer rubbier feel to them. When I start her up on idle i check the elbows especially the right side driver has a “sucked in” or “pinched in” look to it does that go away when I drive the vehicle meaning on idle it’s vacuumed in since the elbows have a softer finish compared to the oem w hard plastic feel to it? I hope im making sense here lol my p0507 went away and I’ve noticed my mpg starting to go up again slowly 07 jgc laredo 3.7 227K ps. bought my elbows from Amazon but I’m also looking to replace them w oem from dealership w hard plastic finish vs softer rubber

[@High_Tech_Mountain]

Great video Oz from start to finish. Appreciate you bringing us along.

[@OzMechanics]

Thanks for stopping by

[@Deadbuck73]

My daughter has a 08 liberty with the 3.7… she just did new plugs a fuel injector in cylinder 6… been almost a week and the light came back on… I so badly want it to be this rocker arm…

[@OzMechanics]

Im hoping it is as well. I quick test you can do it disconnect the injectors and crank the engine over. It should sound consistent when the engine is cranking over. If you here a drop that means that you have a mechanical issue in your engine. And that would lead my to think your rocker might be the issue

[@Deadbuck73]

@@OzMechanics thank you for the reply! She’s already dropped it off at the place she had do the injector. I’m going to call them when they open this morning. Thanks again!

[@ghostmost2614]

Hard to get out. Wait til you put it back in

[@dougdileo4727]

wow, awesome info, i have a jeep liberty 3.7- thinking the same thing has happened

[@Techprone1]

Love the video Oz, great 👍 job!

[@OzMechanics]

Mr Big Shot 978 thanks for watching

[@timothydean]

Dude ur a magician .

[@jasonc.4683]

Awesome work Oz 😎

[@tracycolorado]

sad , assemble by hand . thanks Oz

[@dustinglowa1072]

Thanks man super cool info on the relationship with the graphing, broke it down real simple to understand 👍

[@mrwhamisrick]

I have an 08 Liberty that has a P0302 Misfire cylinder 2. It runs great until it's under a load such as hard acceleration up to highway speeds or pulling a trailer. I've replaced all 6 plugs, coils and injectors. It still has that misfire under a load.

[@jmc5341]

What did the problem end up being?

[@DylanRabier]

Great job. Nice work with the Pico and wps 👌

[@OzMechanics]

Thanks.

[@SuperChris966]

How much would this job cost at the shop? Im gonna look into this just replaced my coils and spark plug and still have a missfire

[@SAAutoRepair]

Nice work my friend. You knew what it was right out of the gate. You just wanted to play. I would've done the same thing. Rock on

[@preludedudesi5208]

Awesome video, nice easy fix other than fighting the valve cover.

[@jamespower5520]

Easy money . I did one on a 5.4 3v two weeks ago

[@OzMechanics]

Ooo yea. Once I did the clear flood I already knew what it was.

[@countryside8122]

My check engine light would come on for a day or two and go out. Had it checked out and it was the number 8 cylinder misfire. When light was on it had a little bit of rough fire. I ran some sea foam through it and about a week later the light went out and has not been in since. smooth as a puppy now. mine is an 3.7 2007.

[@fernyquintero6605]

How can you have a misfire on cylinder 8 when the 3.7 has only 6 cylinders?🤨

[@countryside8122]

@@fernyquintero6605 Well one of those days where I hit the 3 instead of the 4. Sorry for the confusion.

[@Airman..]

Precise diagnostics 👌

[@LMAutoRepairs]

Nice one.... Don't think I have seen those engines here in the UK... 👍👍👍

[@OzMechanics]

Lucky :)

[@thesetruths1404]

Hi I have a 2007 Liberty 3.7L V6, 117,000 miles. Owned it since 67,000 miles. It operated perfectly for the first 30,000 miles and then it started getting a #1 Cyl misfire code P0301. It also seldomly gets a #1 cyl fuel injector circuit open P0201. It must be a very mild fault as the misfire freeze frame data shows it always happens at less than 350 rpm and when cleared it comes back immediately at next startup, cold or hot. So it seems to only happen once on startup as its moving up to regular idle speed. The miss isnt noticeable when driving or idling. Its getting 15.5 mpg fuel mileage. Doesnt burn oil. Doesnt smoke. Has great power. I've changed plugs and coils but no difference. Cleaned air intake, air filter, and ran cleaner through system. I've cleaned and inspected the injector plug and all wires but no difference. Dry / wet compression test of #1, 3 and 5 cylinders all read good: 160 / 175 psi. I'm wondering if there's a mild wire defect for that injector, or just a flakey connection somewhere. Has anyone tried to use a new set of compatible gauge wires and run them to a place closer to the injector control? I can't see where the wires go though. I'm not sure if I should just live with this, or troubleshoot it more. I don’t care about the engine light as we don't have emission requirements. Now that I know the compression is good, I'm not so worried about it. Any suggestions of what to do next? Thanks!

[@JSound713]

Wait till it has a catastrophic failure, then you'll know what went wrong when it finally breaks down.

[@marcogutierrez180]

Hey man do you know if this is the same idea with a 5.7 hemi have misfire in cylinder 4 I changed the coil packs and the injectors but I was told it’s a lifter cause the misfire

[@johnfranceschi3271]

As tech who has been in the business for 30 years, I just need to rant a little. Modern vehicle engineering has so destroyed most of what was ever good about this trade that these engineers have completely ruined this trade and the experience of being a tech. I can't express more vehemently the idea that if you are young and entertaining the notion of making your living as an automotive technician in today's world, run as fast and as far as you can from this insanely stupid and ruinous trade. You Don't need the aggrevation, trust me on this one.

[@OzMechanics]

But with all the upgrades that these newer vehicles are getting allow us to advance. Example: longer driving range, safer vehicles and the list goes on

[@johnfranceschi3271]

@@OzMechanics thats all well and good from a user point of view. I can't argue that modern vehicles are far and away a better experience to have from a user/driver perspective in many ways. It's the hands on fixing them that simply take too high of a toll on my spirit,body, health, sanity. For those who have greater patients than a saint perhaps it is as easy as making pancakes. For me and many it is simply hell on wheels. As SOON as I can, I'm selling off most of my tools and equipment for pennies on the dollar and exiting stage left to spend the last 15-20 years of my working life doing something less insane. The goal is to make enough money that I can afford to pay others to fix my crap or just get a new car whenever the mood strikes me.

[@eddiew.6485]

What causes these lifters to fail and is there anything an owner could do to minimize the issue. Any specific kind of Oil or oil additive ? I ask this because I have this same motor in my 06 Commander that I maintain well beyond what is required in the Service Manual.

[@OzMechanics]

I make sure to add the proper oil weight and as well replace the lifters and rocker

[@antrondon1]

Thank you very much I'm have this problem right now have going to three mechanic no one really knows what's going on

[@OzMechanics]

Tony Tone awesome. Glad this video is directing to your main problem

[@chillbro8811]

I'm having misfire cylinder 3 especially after hitting a bump it trigger the misfire but then comes and goes? I'm thinking ecm but would this be the same for rocker jumping off too?

[@johnlaspisa2711]

Great work!!! I have a cylinder 3 misfire and about to change coils and plugs. Hope I don't run into this problem!

[@jmc5341]

Just curious as to what the problem ended up being? Did the coil fix it?

[@johnlaspisa2711]

@@jmc5341 Yes, new plugs wires and coils

[@uniqueone1653]

Thank you for your knowledge my friend.

[@DavidCastain-q1s]

May look vaguely as a "lifter", doesn't do same job therefore it's not a lifter. Hazarding a guess, call it a Pivot of some sort ,ie: valve train pivot?

[@robertmedina6875]

Great video!! Thanks for explaining!!

[@OzMechanics]

Thank you for watching

[@americanfreedom6417]

Smashed the like. Great pro video.

[@abrahamrivas5908]

I just found this video of the 3.7 misfire because I've been trying to figure out the misfire on mine. It's p0306 which is in cylinder 6. I did everything like your customer did coils sparkplugs and still misfire on 6. See the plug from six was bent and am now going to see if the rocker came off. Is it hard to do this Im not a mechanic but good DIY.

[@gonzgarr1592]

great video OZ with great info

[@OzMechanics]

Thanks

[@felm3283]

Thank you oz for share your work.

[@Dirthauler65]

It looked like you couldn't compress the lifter with your finger 7:58 is that what happens, they get so they don't move anymore? I've seen some vids where they move too easy or stick down, but this one seemed pretty solid.

[@BillyBongwaters]

Thank you .... well done my 2007 dodge Nitro with a 3.7 just had this problem on cylinder number 2.... so new lifter and new rocker..... 25 bucks.... was miss firing then i would hear a odd random snap ... that had to be the rocker banging around loose under the valve cover... I'm glad it s not something to do with the timing chain tighteners.. what a night mare that look like to repair.. and what a shitty design... no clips to keep this from happening? that's what rocker clips are for...Thanks again man....

[@BG-ez6bz]

That was awesome man exactly whay is happening to my 2004 grand cherokee so i guess no need to mess with the injector?

[@OzMechanics]

I would recommend getting a proper diagnosis done

[@BG-ez6bz]

Awesome MR. OZ . quick reply very awesome.🤝

[@derekloria3105]

What was the ballpark compression before the fix ? Thinking its my injector.. switched coil and new plugs with a 120 compression. Appricatte your vids .

[@amr-50]

Great video as usual

[@OzMechanics]

Thanks

[@2000darkball]

Great VDO ever love it and Respect

[@gladmarchatlein8164]

Hi Oz, I'm new in this business. Is it possible to give me an aprox. estimate for this particular repair ? Thanks. Blessings. Keep the good work and educational videos.* Best regards. 👍😎

[@Sroor2023]

Great man ✌✌✌ well done

[@husky4lif3]

i been takin my car to gwt fixed all week P0303 spent 600$ in two days at two different places an both said they fixed the same thing haha an my car still revs up on its own.if i find a good mechanic far or not worth takn my car too lmk who i live in denver colorado i need to get my car fixed still paying on it it feels un safe to drive it as it revvs too 1000/1400 rpms continuosly any one got any ideas its a 03 ford tuarus ses

[@terrymurphy4177]

Very interesting!

[@parkersgarage4216]

anyone doing this be sure to soak your new lifter in oil for 1/2 hr. then install, you dont want to install lifter dry like this. otherwise good vid

[@bobcombs7138]

It looks like that cylinder is still a little low on compression. I'm wondering if it could be due to carbon buildup around the valve and maybe the valve was partially open allowing buildup around the seat area.

[@OzMechanics]

One of my teachers watching this video cleared this part up. He said that because I still had the WPS (pressure transducer) hooked up. That the hose that has tied into the cylinder took space.. which caused the cylinder to look that it was low. Heck out my descriptions and I explain it there as well. Thanks for watching

[@bobcombs7138]

@@OzMechanics Very good! I should have been paying more attention! Thank you! Great Videos!

[@willefixit]

nice repair and diag!

[@danman9017]

very good

[@OzMechanics]

Thanks for stopping by dan man

[@RuanLaVerne]

Hi Sir, I have vehicle 2014 ram1500 dodge power train system po303 cylinder misfire

[@caribbeanqueen5589]

Listen I have a 2009 dodge nitro same engine. I have a po305 code. Two mechanic two tune up within 6 months still same code. Now I am going to show the mechanic this video. Are you in the tri state area because I need a new mechanic?

[@aymenmohamed1134]

Awesome

[@AxisAnimations]

Hey, I have a Grand cherokee laredo 2009 3.7L, some times when i'm driving the car suddenly i feel a high vibration it looks like from the engine but when i stop the car and restart it again after 1 minute i don't feel any vibration, with a scanner there is misfire with cylinder 3, there was a problem with coil number 5, i'v replaced it also replaced spark plugs but still the same problem high vibration and high fuel consuming , any thoughts about the problem please !!

[@carlp.8551]

How much do shops charge for this type of service repair?

[@OzMechanics]

It all depends. It most shops charge a diagnosis fee to verify the complain then charge their hourly rate which can be from 80-125 and hour.

[@johnwilliams6407]

Very good video thank you for your helo

[@armandhammer2235]

Dropped valve seat and thrown rocker arm. Welcome to my nightmare...

[@RichGurska]

Would this be the same for a Wrangler with the 3.6 engine?

[@OzMechanics]

Depends on the yr. The 3.6 did upgrade to a more robust valve train

[@RichGurska]

@@OzMechanics I got a 2015 showing the P0303 code

[@stevepaglia4805]

Help! Where do you find these parts needed? TIA!

[@mthiblo]

Will that also cause the vehicle to smoke

[@OzMechanics]

It wouldn’t

[@freetob1]

DAng I wanted to hear it start and run DUDE!!! WTH???

[@OzMechanics]

Spoiler alert… it ran great 👍

[@vardfriki7274]

Very cool!

[@SeattleSam-ul5hr]

Mine was simply caused by a bad spark plug.

[@flatratemaster]

Nice one Oz

[@madman432000]

How about just change the lash adjusters to solid ones

[@OzMechanics]

Hey Phil Ward I actually don’t know if that would work never really tried it out before. Would like to know what would happen

[@madman432000]

@@OzMechanics There is a kit to do that for the 3.7 V6 and the 4.7 V8.