Zack92MJ

1998 4.0 I6 190k (possible rebuild?)
Misfire on 1 & 2

So, I've changed all of my pugs/wires/cap/the whole 9 yards..cleaned the injectors and moved them all round. (I.e. not in the same cyliders as before) but my misfire is stilll there. Now honestly I can't feel it missing nor hear it..probably mostly because it wouldn't even run when I got it, and its 'always' had the problem.

But the misfire is still there..there when I got it, & there after I've done all of this stuff.. and the misfires always show up together and never alone.
I've been pulling my battery every night to see when my light comes on, and everyday it comes on at the 'end' of the day. After 3 pm when its the hottest and I've been driving around in traffic.

But I don't really know where to go from here?

Wrong gapping?
Timing?
My Jeeps doing crack?
My Jeep has schizophrenia?

I mean seriously I don't know where to go next, I could use some help please..


Thanks in advance,
-Zack

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Loganfwx

Off the top of my head, I'm pretty sure that's called heat soak or something. There were a few years where the exhaust manifold wasn't insulated very well at all, and it overheats part of the block. I thought it happened with 3 mostly, but I don't know. Never happened to me, so I don't know much about it.

tiwvr1

Check compression, sounds like a head gasket.

Slick761

Heat soak would effect the middle cylinders I believe.... if it is mechanical I vote burned valve. Do check compression!

Zack92MJ

Well if it was a head, why would it only do it in the afternoon? I mean I drive around just as much in the morning as in the after noon...and it runs the same (just under 210/ never overheats nothing). Now granite the ambient temperatures are different but still...

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Zack92MJ

I've heard nothing about the valves before, how would one go about fixing that? And how hard are the compression checks to do? Does anyone know of a write up?

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Slick761

I didn't see the only in afternoon thing but that would point toward being heat related. Burned valves aren't that common in newer engines but because of the lean running with these jeeps it is def. A possibility. If you get a compression tester take all the plugs out and test each cylinder with the throttle body wide open. I think you want 5 strokes. The needle on tester will number or cycle 5 times. Do this to each cylinder and write down readings. If you find a low cylinder (15 or so % less then the others) let me know and we go from there.

Zack92MJ

Oh I didn't mean to sound like I was being a dick about resaying 'it only happens is the afternoon' that's not how I meant it.

That's what I was thinking about it only happening in the afternoon, it being heat related..

But I just got the jeep and I got it at an auto auction so I don't know anything about it really

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Slick761

Didn't think you were bein a Dick. Honestly should have read the op more carefully.

Zack92MJ

Oh alright, some people on here can flip a s**t a brick on here pretty easily about nothing really..

But I'm really just learning as I go, and I'm pretty stumped on this one..and the guys at autozone look at me like I'm dumb.. haha

Zack92MJ

Oh! Something that might help is...It seems to idle rough, like...almost thumping..but not really? idk its hard to explain..hardly shakes at all at a stop but once it starts to rool forward on its own it starts the shaking thing..& it seems to be lacking in power when it starts going from a stop..but once it hits like 2500-3000 and beyond , it starts to really HAUL ***.

Slick761

I'm banking on an injector but you might want to check your compression. Cheap n easy.

Zack92MJ

cleaned them and moved them around,,well I cleaned them and put the back in not really know which ones where which..so i either got lucky as hell and put them back in the exact same place or its something else.

And the light always comes on for the both of them, never one or the other. It's always the both of them. (1 & 2)

Slick761

I mixed up two threads sorry..... I think compression is your next step. Inspect the injector harness as well. Injector harness might be old giving resistance and not firing the pintles right. Also, the simplest yet most over looked. Did you inspect each plug as you changed em? The plug will tell you exactly what's going on in the cylinder..

Zack92MJ

Well kinda I was going to do the 703 swap but I wouldn't find my pitles for them? And the ones that I'm assuming were in 1 & 2..they looked like they were burnt they had so much carbon on them..

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