tweezybird

when starting my '01 Cherokee if I don't hold the key long enough I get a rough idle, check engine light comes on. the engine evens out eventually. Will replacing the spark plugs take care of this?

RTorrez1

Since you are getting a C.E.L. Start by having the codes read. Having the codes read is always the best place to start. It will at least point you in a direction to begin. Once you have the codes read post them here and we can go from there.

tweezybird

Code is P0303 and MIL on.

VTJeep

Oh jeez... How are your injectors? Is it prone to happen when warmed up?

tweezybird

It happens when it's warmed up. But it always happens when I release the key to early. If I hold the key down just the right amount of time when starting it doesn't happen.

VTJeep

Well, the symptom is very similar to heat soak, common on 97+ and seemingly more prevelent in the 00-01's. But the odd ignition issue adds some possibilities.

One more question, regardless of if you do/don't hold key over for long enough, does it ever do it when it's cold, not after sitting for a short period, but actually cold.

tweezybird

Yes, it's happened in the winter too.

VTJeep

Well then it sure doesn't sound like heat soak.. That's (almost) too bad because its a pretty simple assessment/fix. But as to the issus, there's gotta be something geeked with the ignition/distribution if it's dependant on the fact that different holding times for ignition produce different ignition symptoms. But this stuff is outta my league so left me see if we can't get someone more qualified involved.. Best of luck.. I'll be following to see what happens!

CCKen

At least pull #3 spark plug and examine it. See if it's oil/fuel soaked or if it looks like it has been running lean (white-ish).


I think you should do a compression check on #3 as well.


Also check the fuel pressure at the fuel rail while doing the cranking bit. See if the fuel pump keeps running while you're cranking. If the PCM does not receive an engine rotation signal within around 2 seconds, the PCM will shut down the ASD relay and the fuel pump. The CPS supplies the PCM with the engine rotation signals.

VTJeep

haha, and this is why I asked.

tweezybird

Thank You, I'll let you know how it goes.


Terri

tweezybird

OK spring is here and I paid attention this winter, it only happened may be a time or two so I'm convinced it is hot soak. We had a warm day and it happened first thing. gonna put on the sleeves and see if that helps.

kclcpa

I have had it happen on a couple of 2001 models with no long-term ill effects. Both were good runners.