Starts, stumbles, and dies when warm

[CherokeeLiberty]

This has been an ongoing issue, but I almost missed my dog’s vet appointment because of it, yesterday.

Sometimes when I’ve been doing errands, I’ll hop in to head out, and the engine fires, stumbles, and dies. Sometimes, I can save it by mashing the gas pedal, sometimes not. Any ideas on what to check?

 

[LibertyTC]

How many miles on the KJ now?
Fuel Pressure test it..Compression test as well ? Recent tune up? New plugs ? IAC clean or replaced?

 

[blackhawk]

Does it crank?

 

[CherokeeLiberty]

How many miles on the KJ now?
Fuel Pressure test it..Compression test as well ? Recent tune up? New plugs ? IAC clean or replaced?

Just over 203k miles. I’ve never done a compression test, and I have not cleaned the IAC. Spark plugs were replaced 30k miles ago.

 

[CherokeeLiberty]

Does it crank?

Yes

 

[LibertyTC]

30k miles is about where I would consider new spark plugs. Coil packs fire very hot, and gaps can get eaten away.
Have you ever replaced the coil packs?
Use NGK spark plugs:
Check gaps & take photos of plug conditions !

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[CherokeeLiberty]

I’ll check everything out this weekend when I’m doing oil changes.

 

[CherokeeLiberty]

Apparently the ‘07’s don’t have an IAC? I cleaned the TB, and it wasn’t terrible. The MAF is dirty, and I don’t have cleaner for it.

Spark plugs were eaten up, a bit. The gaps were all between .044” and .054”. The parts store is closed today, so I closed the gaps to .040”.

 

[LibertyTC]

oh u have an 07, so no IAC.
The ignition fires the plugs hot & best to replace them every 25k miles due to gaps out of spec. Plugs do look correct temp, no fouling.
Is it running ok now ?

 

[CherokeeLiberty]

Yeah, it is. I won’t know if my issue is fixed until I have a day where I make a ton of stops, though. It’s never done it on a cold start, always hot.

 

[CherokeeLiberty]

I haven’t been having any issues since regapping the pluhs, so I guess I’m buying new spark plugs.

 

[blackhawk]

Check the wiring.... One is a positive common for all the coils and a pulsed negative