twobobs

I've had this same problem for years since I purchased the vehicle. After the vehicle is warmed up and then parked for 20 or 30 minutes, normal accelleration to 20 or 30 MPH is ok for 10 to 15 seconds. Then, the engine starts loading up and running rough just like there is too much choke. I then have to feather the throttle to keep it running. It usually backfires once or twice if I try to give a little more gas. Then if I really rev the motor in neutral or acellerate hard or get the speed up to 35 or 40mph the condition clears itself and the engine runs perfect, even at low speeds, until the next time I park and re-start. There are no codes and a factory authorized repair shop couldn't find the problem. I changed the plugs, plug wires, injectors, Distributor cap and rotor, Throttle position sensor, idle air control sensor and map sensor. Any ideas?

93gc40

Vacum or intake air leaks. Plugged cat. Could also be weak battery or weak alternator.

kbad

ditto....vacuums, cat, electrical and fuel system....

....also check egr vacuum (can throw temp sensor code)...easy to do, just remove the egr tube from the side of your intake manifold on the driver's side, below the TB....if engine runs without hesitations, etc., when removed and starts to choke up when replaced, then try purging the egr to clean out the gunk blocking your egr vacuum....

....you could try the other end....jeep fuel tanks are notorious for erosion from the inside causing all kinds of havoc, before you realize it's your tank!.....debris from the tank will clog up the filter and smaller particles will mess up your pump and your injector screens....not fun or easy to resolve!......don't know if you have replaced fuel pump/filter, but if more than necessary, or problems persist, i'd suggest checking out your tank - you'd have to drop it and take a good look see inside - if it 'looks' good, have them boil it just to make sure - or if original, replace it for <$100.

good luck!

illicit

I know exactly what your problem is. Mine did the same thing about a month ago. It turned out to be the #1 o2 sensor. It never threw a cell either. Just unplug it and then drive it down the road to see if it helps. If so replace your o2 sensor.. Thats exactly what i did and no more problems for me.

KenLadd

take out the crank position sensor, clean it and get an new battery... seemed to work for me n i had similar problems... but mine would just up n die

plotski999

X2, I had a problem like this too and it turned out to to the #1 02 sensor, took over a month for it to finaly throw a CEL

twobobs

I had no spark one morning and finally figured it out that the crank position sensor was bad. Bought a new one then took out the old one. The old one had iron filings on it as it is magnatized. The old one may have been ok after cleaning off the filings but the job was too difficult for me to re-install the old one so I just put the new one in. I'll try the o2 sensor. Thanks guys!

twobobs

Hey illicit and Plotski999............You da man!!! My problem is fixed with the new front O2 sensor. I put up with this for 3 years and 30,000 miles. Nobody could figure it out. I guess the sensor was not bad enough to show a code, just bad enough to cause the problem. Thanks much !!!!!!!

plotski999

No problem, glad you finally got it fixed, that's a long time!

illicit

Glad to help out. I know it drove me crazy when I had the problem..