weeks ago I posted about my head gasket we'll that was replaced and cut the coil was replaced ,spark plugs,oil change and oil filter,all sensors have been replaced and a new radiator was put in since it has a small hole,the distributor cap looked new but that is going to be replaced,before all this happen I had a blown head gasket which like I said was all replaced and cut.then after all this was replaced there was no coolant flow so the guy working on it took the tstat out and there was coolant flow so the tstat is being replaced.but there is still a misfire what else could cause this misfire???? I don't know much on the mechanical side I am basically just repeating everything he told me he's been Doing.Anyone that had any ideas or anything please let me know.Thanks

 

You have OBD II, have you read the codes?

 

Yeah replaced my CPS still rough and now codes saying all 6 cylinders are misfiring. Tps ,o2sensor hasn't been changed but didn't think I need to change them.. havnt gone near the iac and pcm hasn't been reset either.everything else has been done.

 

Mine started running like crap after doing a normal tune up. I pulled the neg battery terminal for like 20 minutes. It started like crap but it has never run smoother..

 

Have you cleaned all of your grounds? Our XJ's will real weird if the grounds aren't good.

 

I don't think so where's that at

 

I had a similar issue a few months ago and it turned out to be the coil.... It had a small hairline crack on the side, you could barely see it; replaced it and freakin thin runs like a champ now.... I had replaced the wires, plugs, cap, rotor.... Just about the entire ignition before I discovered the issue.... Oh well, I needed a tune-up. Hope this helps.

 

Coil was replaced unless that one was a faulty coil or something's wrong with it.i am gonna have to just replace it.i didn't change the wires all thought there fairly new Bosch wireset with champion plugs.plugs have been changed twice with the same wireset.

 

Problem started after replacing the head gasket? Have you checked compression? Verified the plug wires are in the correct order?

 

My buddy did it and he's real good he him self said he has done all he could and has no clue.replaced the head gasket took to a machinist new seal and bolts.i mean I can get a compression test done and go from there.if the head was done with a new seal and bolts I don't see how it can be an issue. Plugs ,coil,cap and rotor,CPS ,new radiator and hoses but all this was done while battery was connect I believe.so maybe just reseat the pcm ? And all is good? I wish... Everything replaced btw is all aftermarket btw but it's all good quality nothing cheap.

 

I'm not saying there is necessarily a problem with the head or new gasket, but you have to rule that stuff out, not just assume, and the "Last Thing You Touched" rule applies when troubleshooting.
Here's what I'd do were it mine: Check firing order and fuel delivery because they are quick and easy, then check compression. If that doesn't get you going, check valve operation and vacuum integrity (no leaks) with a vacuum gauge.

Did the multiple cylinder misfire code start after you changed the CPS, or was it there before?

 

Yup, no sense in throwing parts at it until you do the free stuff.

 

Multiple misfires were before everything was replaced.replaced everything that I was saying before except CPS still was ruff and stalled a couple times. Replaced CPS ran awesome first run second run started light was back on drive for couple days checked light and that's when it said all cylinders were misfiring . Also Tps hasn't been touched yet iac hasn't been cleaned fuel pressure was checked fuel rail was cleaned.throttle body was cleaned and no vaccum leaks that also was takin care of.

 

Aftermarket part?

 

yes almost everything that's been replaced is aftermarket CPS is a airtex brand