Another ZJ Problem!

[jeepinjon]

93 4.0 Ltd.
268,000km
Seems like an idling problem. I've read recent posts about this, but none really helped my situation.
First off, it makes me feel so guilty when it happens because 80% of the time it happens at a drive-thru!!

I'll be in line, stopped in gear. When i go to pull ahead, and let my foot of the brake...as soon as the jeep tries to pull itself forward, it shudders and shakes and rpms drop from about 750-250! This has happened a few times now.
Also, it happened at a red light once.
But it always seems to catch itself after 1 or 2 seconds of shaking UNTIL TONIGHT!
Grabbing a coffee, i was stopped, then pulled ahead to the window *shudder shudder* dead.
Whoa! So i throw it in park, start it up, and it starts fine, pull ahead and thats it, I go back to my house.

Is this a fuel distributing problem? Throttle body?
Any help or tips is appreciated.
Thanks in advance!

[barmanjay]

sounds like some sort of idle air control thing

[4PLAYZJ]

How is your battery? I have found that jeep electronics don't run so well when the battery is failing and the engine is running on alternator power only.  Had a couple of customers with a similar problems and the fixes were batteries(one in an xj and one in a zj).  If you battery is good then check you IAC motor.  Just a couple of ideas.

[RedApe]

I would look at replacing the TPS....Throttle Position Sensor.  Symptoms sound very familiar. 

[JackstandJohnny]

i had a similar problem on the trails.  when going down hill she'd goto 250rpm, then die.  this was because my idle motor was dirty as hell (ithink).  sprayed it with carb cleaner, and it has stopped kind of.  does it sometimes now, but only on startup. just hit 700 rpm then dies again.  so haha, i guess i'm unsure lol

[cLAY]

Ha Ha! Reminds me of my sisters ZJ when she first got it. It completly died in the drivethru at Tim's. Funny thing was I was inside in the line up. I get up to the till and the clerk asks my name an then tells my sister's Jeep was blocking the drive thru! She had seen my truck in the parking lot and asked the clerk to relay her perdicament to me. I looked out the window to see 3 guys(from the cars behind her) pushing her thru the drive thru! By the time I got out there they had her pushed into a stall.

She had let it sit for a long time and the battery ran down. They boosted it and she drive from home(3 blocks away) and into the drivethru. The battery had not had a chance to recharge yet and for some reason when she stopped at the window the engine died and did not have enough juice to restart. I boosted her then told her to take it out on the highway and run it. After the battery charged up it seemed ok. It was good for about a month and then the coil went. Just before the coil went it started making those same symptoms again but only for a day or two before the coil totally went.

As posted above check the battery(and connections) as well as the IAC motor. Funny thing is right now my ZJ tends to stall right after startup, its fine after a minute or two.  But this didn't start until after I cleaned the IAC, go figure!

Funn

[jeepinjon]

Thanks guys.  After those replies, I'm going to lean toward the battery. I killed it more than a few times. Fortunately, I have a new battery already, and just havent installed it yet. I'm going to drop it in tomorrow, and hopefully that'll solve the problem.
Thanks again for the tips!

[cLAY]

Let us know how you make out...