1993 Grand Cherokee problems HELP

Ok I have a 1993 Grand Cherokee, I have a couple of problems maybe someone here can help me. First off, the transmission. Shifts very sloppy at times. slow shifts when it does, doesnt want to shift alot of times, have to let off the gas to get it to shift. then when it isnt having any of the above problems it shifts thru the gears really fast. Any ideas on this one? Second is the oil pressure gauge is going psycho on me, starts up and goes to 80 then down to 40 then bounces while driving, never did this before. third is the engine seems to be missing really sitting at a stop you can feel it miss. changed the plugs cap rotor everything in the distributor. the truck also gets VERY VERY bad mileage. we are talking 200-250 Miles to a full tank of gas thats a 25 or so gallon tank. on top of all that it PINGS, REALLY bad.... PLEASE help anyone have any ideas where to start... i have been reading and see that the TPS might be the shifting problem. IS that possible? thank you in advance...

Jackie

Hi Jacki

First the transmission.

How long since it was serviced. I mean a full oil and filter change not a machine flushing job. And the filter can reduce the flow to the transmission and affect the shifting.

Some of the seals can get hard if the fluid is left too long and they no longer seal. Some of the new aftermarket kits have better seals and some times one of the clutch pistons needs replacing (depends on the model.

Not much good news there - sorry.

The oil pressure problem sounds like one I had. there is a service bullitin on this problem for 1996 jgc's but I helped mine by flushing the engine just before changing the oil. I did this several oil changes in a row and the fluctuations have almost stoped. In any case this wont hurt anything.

Another possibility here is the wire to the sending unit. Is the connection loose?

The sending unit could also be bad. It is not an expensive part.

While your at it, have a mechanical pressure gauge connected to the engine. The mecanical gauge is more reliable than the electonic one any way.

If the mechanical gauge jumps around, for sure try the engine flush.

The poor gas mileage problem is best approached with a good tuneup but sounds like youve done some on that. A scope check and checking for codes will give you another starting point.

A miss fire can be caused by ignition, fuel, or compression problems so a check of all three will give you the best picture.

let us all know how it goes and what you find.

JD

Thank you to everyone that helped with this problem. changed the TPS and it worked much better but...... still having more problems.... i am going to post about that next...

You have a vacuum leak, a bad one. it wont upshift because it thinks your accelerating. there are two sorces on the passenger side of the intake manifold, one going to the pcv valve and one going to the resevor. on the drivers side the is on that goes to the brake boster. other vacuum leaks could be bad valve guides, manifold gasket and throttle body gasket. good hunting.