vr4operator

Happens within the first 10 minutes or so. I'll get out of the driveway and sometimes it'll act up, sometimes its a mile or two down the road. It'll drop RPM's like its gonna die, then surge, hesitate, surge, etc. If I floor it (if I have some room) she'll launch forward and it seems to clear. But it'll clear on its own eventually. Seems like once shes warmed up, its ok. And yes, does it at idle.
Did it when i test drove it prior to buying. But looking over everything else, she looked like maybe she sat for a bit and def was behind on maintenance. Air box was full of acorns and dirt, air filter full of crap and rusted, etc. So I figured it was a bad spark somewhere.

Just cleaned and put in a new air filter, plugs, wires, cap n rotor and its still doing it. I'd blame a dirty fuel filter or pump, but they don't give a damn if the motors warmed up or ice cold being back there in da tank.

Any ideas?

Thanks,
Butch

PS haven't gotten around to the drivetrain or changing oil yet. DOubt a dirty tranny filter would cause this kinda bucking, but ya never know with computer cars...

klump

any codes? mine did the same thing and it was o2 sensor related.

Radi

Sounds like your IAC may be sticking instead of moving freely...might pull it and give it a good cleaning.

residentg

I had a similar issue - replaced O2 sensor in exhaust header, problem solved

milodajeep

I've just had the same experience. I found the IAC valve had all carboned up and seized the needle and slide. Simply removed and cleaned IAC valve slide and reassembled.
Now runs beautiful hot and cold and acceleration is also a lot smother from standing start.
It's worth a try and won't cost you a thing.

vr4operator

Thanks all. I'll try both the IAC and O2 sensor

klump

while the IAC is a cheap thing to clean and fix- the o2 isn't "fixable" and at 60 dollars minimum, I would look into further testing before blindly replacing it.

arorton

....where are you buying $60 o2 sensors??

klump

bosche after rebate

arorton

I see no point in purchasing the most expensive o2 sensor in the world.. it's like paying for a premium ****, when it really doesn't make much of a difference...

vr4operator

Dropped by my local Jeep dealer, hit the parts dept and asked for a IAC. Now, I gotta tell yeah, I own a VR4, twin turbo fast as hell and it thinks it needs Lambo parts under the hood (meaning all the parts on that car are expensive). But the new IAC I put on the VR4? $45. So, I'm thinking, Jeep, eh, $30-$40. Imagine my surprise, not SHOCK when he told me $120, but had to order it. I told him, ty, but I believe I will be cleaning the original one out with carb cleaner. $120?!?!?!?!?!
As far as the O2 sensors. I'm a firm believer in Berrymans B-12. It has gotten many CEL to go away after it cleaned out the sensors. Two cans for the first 2 tanks fills of gas. Its like Seafoam, but $4 at Wal-Mart. I'm not a big fan of any additives, but I SWEAR by this stuff. Cleans fuels systems good

klump

the rear not so much, but upstream you would be amazed. everyone here hates on bosche but ive used em for 3 different jeeps and have had no problems. same goes with most (not all) the stuff i get from the parts warehouse.

OEM parts from the dealer are gonna set ya back, thats for sure. and are you saying you've used a fuel system cleaner to "clean out" the sensor after its already been diluted with gas and then exploded? i mean maybe, but I think if i got my 60k outta my sensor id call it good enough and just get another.

vr4operator

Yeah, thats what I'm saying. As I say, I don't buy into additives anymore than 95% of the crap at GNC. It just makes you feel better. but I've used Seafoam in the past and then found something just as good for half the price. Safe on filters, keeps the whole system clean, works wonders on carbon deposits (my '71 Vette LOVED it, she runs rich). Like I say, for $3.17 at Wal-Mart (just got 10 more for the winter, I have alot of vehicles), its great insurance. I'm gonna run a full tank thru and see if it fixes the issue, if not, then we'll go with plan B and get the sensor(s).

I did take the throttle body off and aprt and cleaned it. Holy jeez it was full of dirt and crap, especially the IAC area and IAC itself. I cleaned the IAC real good, but it may get replaced with the sensors, just to cover bases and cross a issue off the troubleshooting chart.

BTW, Advance Auto has the IAC for $72, not bad. Went to 3 boneyards today looking for a drivers side taillight and ALL the jeeps were missing the LEFT one. WTH? Advance had it new for $75. Needed it asap for inspection. Woulda rathered the $30 boneyard price tho, lol

arorton

What year tail light?? I found my 97+ one on eBay for $28 or something like that

captainwoot

I totally agree with the op's suggestion of an 02 sensor, I had a simliar issue...(search my posts) good luck!