Questions and Answers

Jeep Cherokee Has Strange Surges Q. I have a 1988 Jeep Cherokee 4WD 4.0 liter automatic transmission with about 175,000 miles on it. About two months ago it started surging and bucking but not all the time sometimes it will run fine for a week or so then have a bad day and so on. The first shop I took it to said the lip seals in the transmission were bad and they charged me $1500.00 to replace the transmission.

Well I got it back and a week later it started the same thing again. Since then I've had it to three different shops and they all say there is nothing wrong with it and all the sensors are fine and there are no trouble codes.

The only guess they could give me was to put a $30.00 bottle of injector cleaner in it that did nothing. I've checked all vacuum connections replaced the O2 sensor the TPS and the crank positioning sensor all to no avail. Can you please help?

Thank you…

A. I doubt very much that leaking transmission lip seals would cause the symptoms you described. If they specifically said they were the cause of the problem I would go right back and say "HEY! You told me this $1500.00 transmission would fix the problem but it didn't. What are you going to do about it?!?!?"

With that kind of milage on it, I would suggest giving the throttle a good cleaning. Often that will clear up this kind of problem. And since these symptoms can be caused by bad ignition wires, I would consider replacing them as well. In fact, if it's been a while, a good tune-up with new spark plugs, distributor cap, distributor rotor, ignition wires, air and fuel filter would be a real good idea. Don't forget the ignition timing too. This may cure the problem also.

Once we know the basics are good, and the problem still exists, I would do a fuel pressure and injector balance test to make sure the fuel delivery system is good.

Then the next thing to check is the EGR system. Try unplugging the EGR valve and see if the problem disappears. If it does, then you know the problem is in the EGR system.