so today i was driving around in the jeep, i stopped at a traffic light and noticed it was running weird, so i went home, let it idle and you can tell its missing, but its not throwing a check engine light or anything, but it idles like crap, so i pulled all the spark plugs, they look fine, its only been about 30k since i changed them anyways, i made sure the gaps were good and put it all back together, same thing, and still no check engine light, ive got the stupid distrubuterless system on my jeep and so my first thought was maybe the coil pack went bad, ive had it happen before but when it did that it misfired way worse then it does now

oh and its obvoiusly a misfire cause you can hear it in the exhaust and you can smell it to, it just smells like straight fuel, i reek of it now from just being around it from when it was idling

 

my 99 xj has a similar issue. it will hesitate and shudder and act like it is going to cut out. it will only do it at low idle. once the throttle kicks to high idle, the issue goes away. so far i have replaced:

plugs/wires
cap/rotor
IAC valve
TPS
flucshed gas lines
checked pump/filter assembly

HAVE NOT REPLACED:

o2 sensor
coil
fuel pump assembly

for a while the issue went away! huzza! but hen it came back... and now it will, very randomly, happen again. as i stated before, it will only do it at low idle, which makes me think the the TPS or IAC valve is still funky... i got the IAC off line, and it was marked down to cheap from very expensive... so i wonder if i didnt get a bunk part... but it wont throw any codes, which is its own issue... if it threw a code, id have a direction to go, but till then.........

 

yeah see i dont have a distrubutor or wires or anything, i wish i did, just spark plugs and coil strip, and no cel, so i have no clue whats going on

also some more info, i checked the head, no cracks, since my year is prone to them, i could see the tops of the cylinders when i pulled the plugs out and they are all clean, so there isnt any excessive carbon causing any problems, i have no clue why its doing this

 

did you check your oil?

if its milky it may be a head gasket or cracked head. you cant really tell if you have one just from looking in the plug holes. also, any excessive moisture at the tailpipe?

maybe run some fuel injector cleaner thru it?

 

I assume you are talking about the 2000 model year?

If so get a good Code Reader, I know you said there is no Check Engine light but there could be " Pending Codes " and you need to read for those.

I was looking at a 1997 XJ and one of the first things I did was hook up the reader and look for PENDING CODES!

Understand that a misfire fault will not turn on the Check Engine light unless the fault occurs a specific number of test cycles concurrently.

I have an 96 XJ that was throwing random misfire codes ... for me it was simple, the cap.

 

yep that was the first thing i checked, oil is good, not mily at all, and the tailpipe isnt putting out more then it usually does, its pretty cold out so it has some, but once it warms up it stops

 

then i would start testing your coil packs or look at your injector spray pattern.

 

yeah the coil packs were my second thought, ive had them go bad before and supposedly they last 100k but maybe its just a bad one, and the injectors are fine cause they are brand new and ive checked them a few times to make sure they are good

 

just because the cel aint on dont mean there is not code to read get the codes read at auto parts strore

 

yeah im gonna go do that in the morning, hopefully something will show up, im just going by the symptoms it had last time it did this and they arent as severe this time, but you cant always go by what you think lol

 

just curious, what does a bent pushrod sound like, and what are the symptoms, i dont think thats what happened, but its just one more thing i can rule out

i also have some more info that should help, my stepdad said i should check that map sensor, ive read that those can cause misfiring when they go bad, and im thinking that makes more sense, since its running really rich, and i can hear what sounds like its choking through the cold air intake, i dont remember hearing that last time it misfired

 

replace your aftermarket IAC and/or TPS sensors with FACTORY sensors either from the dealership (expensive but never faulty and last forever) or from the local pick and pull. My 96 XJ has sensors with over 250k on em and run way better then the aftermarket sensors I tried to put in there to fix a problem that wasn't from them in the first place! those crappy cheapo's went bad in less than 2 weeks and caused my jeep to run rough and shudder until warmed up then randomly skipped/jumped at low RPMs. put my old sensors back in and it's all smooth!

 

well i thought i had it it figured out yesterday, since i have hood vents they caused my spark plugs to rust, so i figured that one of them wasnt getting a good ground, so i got new ones and replaced them and it helped a little, but it still is running rough, and still no check engine light, my next guess is the coil packs, but last time they went bad they threw a check engine light, and it idled way worse than it does now

when i get some time today im gonna run her over to auto zone and use their code reader to see if there are any codes that are hidden

 

Just an FYI a bad part does not always throw a code. I had a TPS that was shot and did not throw a code. It tested fine but the spendil inside was just off by a millimeter causing the throttle plate to slip.

 

yeah i know, i wish it would though so i know, how did you find out it was the tps