I have a 99 Cherokee that I recently bought, it was previously a police vehicle, and it was sold in January of this year and sat for a few months on a lot, and I dont believe it was started really at all. It runs and drives perfect, the only issue I have encountered is starting it and some idling issues.
When its cold, it takes a few cranks to get it started, after it starts it idles really rough for about 30 seconds, and it really bogs down if you put it in gear...it never has stalled, just idled rough and it has a little trouble starting.
I really dont know if it was just because it has been sitting or something else.
There is no check engine lights or any other dash lights, gas milage seems okay, everything else is fine...should I run a few cans of seafoam through it? or does it have a fuel filter or some sort?
any suggestions would be great.

 

it wont hurt it...give that a try, clean your iac and your tps as well.


your 99 has the filter and the fuel pump made all in one...you got to replace it all and drop the tank.

 

thanks, will give it a try asap

 

any one else have had an issue with something similar?

 

my 99 runs perfect but i have to let mine idle for a long time while im on a call and it started idling really really rough. i installed the high idle switch and now my problems fixed. just be sure to turn it off when not idling or it'll cause your jeep to do weird things...

 

mine has the switch factory because it was a police vehicle, it doenst matter if it has it on or not when i first start it up, it still idles bad for about 30 seconds regardless

 

oh and the jeep has just over 100k on it, and was maintained well by the city before it was sold..a tune up was done recently as well

 

i don't know about intial start up. im sure the jeep was taking care of cosmetically but other wise idk. im an EMT and a Firefighter and i can tell you, our vehicles are washed and cleaned everyday and they have a regular tune up but they are still put through hell. not saying your jeep was though.

 

yeah I know that it was taken care of cosmetically and oil changes and stuff like that, im sure it was driven hard for part of its life, but thats the only issue thus far, so im fairly happy. Im going to run a can of seafoam through it and see what it does

 

could be old gas.

 

I had a similar problem. My 97' (160k) would idle rough when cold, and shake and shudder when you put it in gear and idle along using the brake pedal, never stalled. Run better when warm but still a bit rough.
I replaced the spark plugs and the upstream O2 sensor and it runs great now.
I think that for $12 it never hurts to put new plugs in, properly gapped. Also, the life of an O2 sensor is about 100k, so if yours has never been replaced it could be a good place to start. I didn't have any codes for my O2 sensors either.

 

possibly when I had first got it but I have driven it probably 300 miles+ since I have gotten it...always used premium, I have a suspicion that it may not be the gas

 

sounds exactly like what mine is doing. I might get some new plugs, couldnt hurt. The vehicle just flipped over 100k, so I might do that as well..how hard is that to access and change?

 

I'm just learning some of this more tecky stuff, but saw something you might be interested in. The coil in the dizy, forget what it's called, what it does is tell the brain weather (say #1), is coming up on compression or exhaust, for timing the injector pulse. (the cps & ECU handles spark timing)

If the ECU gets no signal from the *&%#coil, it will batch fire the injectors and it will start. Then the ECU sorts it out and fires the injectors normally after a bit.

As far as idle I'd start with gaping the plugs and looking for vacuum leaks.

 

I will start with the plugs and maybe run a can of seafoam through it for good measure..then maybe look into the more technical stuff after that