DM_MKV

1996
4.0l
150k miles
5 speed

Sorry to create another "misfire thread" but after reading all other search results and trying those fixes I am still getting a code. The misfire is barely noticeable at idle/driving.

Things replaced:
Cracked header with APN header and new gasket.
Crank shaft position sensor.
TPS
Sprak plugs, wires, cap and rotor.
Fuel filter
O-rings on injectors

Took care of original code which was misfire in cylinder 1, 3, 6, after 50 or so miles code came back with misfire cylinder 3. I am going to check the wiring to the injectors tonight as well as the spark plugs for fouls. I will post a pic of my findings.

Other issue that may help someone more knowledgeable then me:
Car has problem starting on first try take about 10 sec of me cranking the key to start it. I don't like doing this so I crank it once and the turn it off and crank it again and it starts right up.

Thanks for the help.

Derek

dans01classic

My 01 does this, over time i have replaced everything including all new coil packs (only on 00-01 i think). eventually i got tired of spending money and not fixing the problem so i just bought scanner so i can clear the code. Comes on every now and then and just clear it. I've even cleared the code and got it inspected right after one time. So it solved my problem.

Not too sure about it not starting on the first time other then when vehicles get high mileage (dont know if yours does) they tend to that. I had a commuter 97 saturn one time that no matter how long u turned the key it would not crank untill the third time. Always on the third time. it was just rutine for me.

stupid me, it says right at the top how many miles it has. my bad. Idk you've got ohlmost 50k less then i do and mine doesnt do that. Good luck.

CodeXJ

Dunno if you can do this on the 4.0L with coil packs, but on my old BMW I had a persistant misfire on #2. I swapped #2's coilpack with #1, and the misfire moved to #1. That pretty much identified the problem right there.

DM_MKV

I don't have coil packs. But I am going to switch the injector and plug tonight to see if it stays with those two and if it does then i will switch them separately and see which one causes the code.

Thanks for the help. I will try to update with what I find.

CAEMI

First, pull the spark plug. If it looks fine, ignore the problem. If it's funky, pull all of them and compare. Label your wires..., btw.

If plugs are gunked up, c/b valve seals leaking oil into the chamber.

Hate to sound like a broken record, but there is only one diagnostic tool past this point that I know of:

Leakdown test.

CodeXJ

Oh yeah, sorry, was referencing the guy with the '01

That sounds like a good idea.

DM_MKV

I will pull them tonight and post pictures.

Thanks for the update.

DM_MKV

Spark plug 1
Spark plug 2
Spark plug 3
Spark plug 3
Spark plug 4
Spark plug 5
Spark plug 6
Rotor
Rotor
Cap

Tested fuel injector's resistance, 12. Unplugged injector while Jeep was running and it started sputtering, did this with each injector and same results. Hope these pictures show someone something if not i guess it is time to take it to a mechanic and see how deep they want to stick it. Wires all looked good. I did a full tune up about a 1000 miles ago.

Thanks for looking.

windsoreight

Pull #3 injector out turn it upside down and tap it on a piece of white paper. See if it is full of debris. You can also swap it from to another cylinder and see if the misfire follows it.

CodeXJ

This

thelaststarfighter13

Have you read anything about the third fuel injector getting the most heat. If you are running the jeep harder then the average daily driver this injector might get to hot and cause it to malfunction, thus causing the misfire.

DM_MKV

Tried to switch and didn't make a difference. Also a bit of carbon came out of the plug. I am going to get new plugs and sea foam to see if it helps.

CAEMI

Before you spend money on new plugs, switch plugs around and see if the miss follows.

BUT, your plugs look fine. The injector switch didn't work, either. I'm left with one idea...the computer has a genetic mutation. Some people call this "personality" or "character".

I'd leave it alone. So far, there does not appear to be any evidence that it is causing a problem...other than running up your credit card statement. I'd chalk it up to character and live with it.

DM_MKV

Yeah I think I am at that point. There are other things I need to spend money. I am going to switch things around and sea foam it. Thanks for the help guys if I find anything I will post it up.

irs009

switching plugs around would verify the integrity of the ceramic insulation...good idea.