Doesn't hurt to replace. I'll keep the old one too.

 

This seriously never gets old

 

we love the parts cannon

 

Haha. Well it's now replaced. Let it run for about 10 minutes. And no misfires so far. Cleared the code as well.

Old one had the plastic cracked in a few places.

I guess we'll see in the next few days if the CEL comes back on.

 

I really hate changing them too. What a terrible design.

 

Code hasn't come on yet, but it's still misfiring some. I guess over the weekend i'll do a compression test.


I read on a few forums it's possible the valve springs need replaced. Seemed like it was mostly a wrangler issue, but that 97-99 4.0s could have a "bad batch" of valve springs.

What do you guys think?

 

An engine needs 3 things to fire. Fuel, spark and compression. Judging by what you've done so far and you are absolutely sure it's not related to the injectors, it has to be a compression issue.

 

Could be like my cylinder one. Compression was in 130's all other cylinders in 140's. But for a leak down used air hose at 40psi and filled through spark plug hole. Cylinders 2-5 equalized at 40, cylinder one only made it to about 10psi. Chrysler switched to lighter valve springs in 96 I think it was. I have read that they were prone to premature wekening and I'm hoping that's what my problem is.

I have tried mystery oil and techron in the gas. I did the water thing but may try that one more time with more water. Still have the misfire though. Also tried pouring mystery oil through the throttle body and turning it over with spark and fuel disable hoping to coat the valves with it. Let it sit for a while then fired it up but that didn't help.

 

I'll be doing a compression test soon. Only thing left. I'm half debating on just getting another motor and swapping it in and rebuilding mine.

 

Compression and leak down test. It may only need valve work which is much cheaper and simpler than buying another engine, swapping it in, rebuilding your engine, then swapping that in.

 

I'm pretty sure the piston rings are fine. It's not burning oil.

As for valves. The head needs to be removed to actually replace the valves correct? If so i need to buy a new head and head studs because i've already done a head gasket and they cant shave off anymore off my head. So getting those plus the machine work done would cost more than a new engine and take just about the same amount of time.

I'm hoping I could just do valve springs if that's the case.

 

Ordered a compression tester. Should be here tomorrow and this weekend i'll have a few little projects with the Jeep.

 

You can pick up a cheap leak down test kit at china freight if there is one nearby. They work fine.

 

Just did a quick test and cylinder 6 is at 120 while 2 is at 150.

Will go back and do all of them, but i'm thinking its worn valve springs.