Novak Conversions Jeep Wrangler TJ radiator

P0301 cylinder 1 misfire: is this spark plug oil fouled?

WranglerNoob

WranglerNoob

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May 15, 2024
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Massachusetts
I have a 2001 Wrangler SE with the 2.5L 4cyl engine I recently acquired. I bought it with the CEL on for cyl 1 misfire, I assumed it may just need a tune up.

Yesterday I installed the Quadratec tune up kit, so I changed:

Oil
Oil filter
Plugs
Plug wires
Distributor cap and rotor

I cleared the code and when I first ran the engine after doing the tune up, the same code came back after a few minutes of it running.

I cleared the code again, and then drive the car for 30 mins and the code did not come back.

I just want to make sure I have resolved the misfire, but I am afraid there may be more advanced engine damage. Taking a look at the old spark plugs, the cylinder 1 plug looks oil fouled especially at the electrode. See picture below.

IMG_0231.jpeg


Any advice here is appreciated. I would like to have an idea of what may be happening, if I should be concerned and what the next steps are.
 
I'd say it's fouled, yes, probably oil. The others look like they have some deposits. There's others who may weigh in with more experience reading plugs.

When I try to read them I use something like this chart: https://www.oldclassiccar.co.uk/library/spark-plugs.htm

It's got a good description of what's going on with each type of condition.

Bottom line, you've installed new plugs and you can check their condition after some use and get a better idea of what's going on.
 
So I pulled the valve cover and turned the crankshaft as I recorded the valve stems. They seem normal to me? I am no expert though. The misfiring cylinder is closest to the camera and it looks like both valves are traveling. Attached the video for people to look at.

Didn’t have much luck with the bore scope, should I do anything else while I have the cover off?

Video:
https://imgur.com/a/drlanZD
 
My 1st recommendation..is
To **properly do a cylinder leak down test**-and properly do a compression test for each cylinder..*these test results will let you know if each cylinder is healthy or not. If some are and some are Not..then you have the evidence of your problem or problems…then work backwards from there to figure our what is going on..

If you don’t do this test..most likely your gonna be guessing and throwing parts try to fix what you don’t know to fix ..
 
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Thanks Buck,

Do you think a harbor freight leak down tester would be sufficient?

I took another shot with the borescope down the misfiring cylinder. One picture is of the head of the piston but in the other two it looks like there may be gouges in tge cylinder wall? Sorry for the bad pics, I have to take a pic of the borescope screen with my phone.

IMG_0269.jpeg


IMG_0268.jpeg


IMG_0270.jpeg
 
I have a Harbor freight leak down tester for years..it when used properly..helped my locate burned exhaust valves, leaking intake valves and excessive air blowing into the oil pan..
I still have that kit and use it when needed
 
Just FYI..take a shop vac ( if you have one) and use it to suck up al that FM that I see sitting on you cylinder head *where your rocker cover mating surface is..and anything else that loose FM around your rockers
 
WranglerNoob said:
So I pulled the valve cover and turned the crankshaft as I recorded the valve stems. They seem normal to me? I am no expert though. The misfiring cylinder is closest to the camera and it looks like both valves are traveling. Attached the video for people to look at.

Didn’t have much luck with the bore scope, should I do anything else while I have the cover off?

Video:
https://imgur.com/a/drlanZD
Click to expand...

I watched this like 3-4 times and I don't think that front-most valve rocker ever moved. I believe that's the exhaust valve. That might be worth further inspection.
 
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Fulton_Hogan said:
I watched this like 3-4 times and I don't think that front-most valve rocker ever moved. I believe that's the exhaust valve. That might be worth further inspection.
Click to expand...

Exactly what i saw, ( or didn't ). No movement from the front rocker. Maybe a bad camshaft ?
 
Buckz6319 said:
can a dial gauge be affixed somehow.. to measure lift at it highest point with the manufacturer cam lift specs( if the lobe is not too bad) ?
Click to expand...

Yeah...but we can pretty much already see you have a problem.

A leak down test would confirm it.

Question is...what are you going to do with the info...

You're probably going to need to tear down the engine. At least the head...I'd get that off to look over the valves.

If you've got a wiped cam lobe then you've had metal through all your bearings.

-Mac
 
macleanflood said:
Yeah...but we can pretty much already see you have a problem.

A leak down test would confirm it.

Question is...what are you going to do with the info...

You're probably going to need to tear down the engine. At least the head...I'd get that off to look over the valves.

If you've got a wiped cam lobe then you've had metal through all your bearings.

-Mac
Click to expand...

Mac sir, I know what your saying bust..I just hope the OP understands.. and hope he gets a helping hand by someone knowledgeable with this procedure.
 
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Hey everyone,

Sorry for the late response, I stopped getting notifications to the thread for some reason.

Thank you all for the responses, it looks like Imgur cut my video off early. Please see this link to the rest of the video where you can see the front most rocker does indeed move:
https://imgur.com/a/M8RDX6w

Thoughts? I found a 2.5L on Facebook for only $500. I don’t feel confident taking off the head but I’m sure I could manage if I needed to. I feel more confident in swapping the engine. The replacement engine has 130k miles and the seller reports that it ran good before it was pulled… would this be the better route?

I was planning to put a deposit on the engine tonight so opinions are appreciated beforehand.

Thanks!
 
If that rocker is indeed moving let's get a good leak down test.

I'm thinking that pulling the head might let you look at the valves...if indeed that's where the issue is...and lapping or replacing valves isn't too hard.

Personally me...I'd rather bird in hand than an unknown condition engine. Mileage is no real indicator. It's 20 years plus old. That being said...$500 for a hot spare engine is tempting. I'd do it because I've got space to store it inside. And I'd go through the new one with new bearings and check everything out before installing it.

These engines are pretty simple, can survive a lot of abuse, have high mechanical tolerances and you can get away with a lot.

-Mac
 
Thanks Mac,

Yeah I would like to do a leak down test. I am worried this engine on marketplace will get snatched up quickly though, and if I do end up needing it I would like to have it on hand than wait for another to pop up at a reasonable price. I've bought things from the seller before and he seems honest, so maybe I should just buy it anyway? It does come with all of the pumps, wiring, hoses and manifolds so it should be a trvial swap.

On the other hand, if I do not need to spend $500 I would rather not. Tough one...
 
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