Hey guys, new to this forum but been a fan for years. Been a jeep guy for over a decade and have owned my 99 Cherokee sport for over 7 years. She has run top notch since I got her. This winter I have experienced a problem starting. I'll try my best to explain:

This only happens to the truck during a cold start up, also seems worse when its damp/raining out. When I start the truck when it's cold, 80% of the cold starts it will run for 1 to 3 seconds then stalls immediately. Then I proceed to start again giving a little bit of gas, it fires up but runs rough and sounds like it's mis-firing for about 5 - 10 seconds or less. During these 10 seconds of rough start I have to keep my foot slightly on the gas to keep her from stalling and RPMS are irregular (400 - 1100). About 15-30 seconds later it sounds like it clears whatever issue it has and then idles perfectly normal. Sometimes if I don't let it idle long enough and start driving down the street, the truck will then stall at the first stop sign. (Coming from 2000 RPMS to foot off the gas to prepare to stop and it will stall only when cold)

When the truck is warm it idles and drives perfectly with plenty of power. When its warm the truck will idle for 30 minutes at the same RPM's

Any idea what can be causing this?

Thanks!

 

Could be a number of things. But things I would gravitate to first (in order):

1. Service/clean throttle body and IAC (Idle Air Controller). I think the IAC may be failing when cold based on your description.

2. Have the battery tested and service/clean and reattach all the main starting/charging connections and grounds. (battery terminals, ground stud behind dipstick, ground studs on block behind the alternator, body to battery ground wire.

3. Tune-up inspection (condition of plugs, wires, distributor/cap (if applicable)).

 

Thanks for the response!

I am going to do # 1 this weekend. I don't believe it is a battery issue, I checked all terminal connections and battery connections/grounds looked great. Plus just got a new battery.

I also find it strange that when its damp out the truck takes a bit longer to idle correctly. (Spending more time lightly on the gas to keep it from stalling)

 

Replace the distributor cap, rotor and toss in some Champion spark plugs. Fixed my '99s startup problems. And yes. Clean your IAC.

 

Will do, thanks for the response!

 

Don't forget to let us know the results - especially if the problem is fixed!

 

Definitely! I will clean the AIC/Throttle body tomorrow morning.

I'm guess its never been cleaned in 19 years LOL

 

put some dry gas in it.

 

crank sensor, cam sensor, fuel pump

 

i would verify fuel pressure first. you can rent a gauge at vatozone. mine had similar issues when the ignition coil started going south.

 

Hats off to you my friend!! Thank you for the info and the help!

I cleaned the Throttle body and IAC yesterday, the dirt that came off this thing was unreal... put it back in, lubed up the throttle body... My jeep fires right up like the day I first got her.. She's like a new truck

Thanks everyone for all the advice. This forum rules!!