1988 Cherokee Pioneer 4.0 auto trans. 4x4. My Son drove Jeep for several months, brought it back because it was not running good. Done some testing found the TPS was bad, changed TPS and now it idles fine, give it a little gas and it starts to move, then give it a little more gas and it Hesitates and stalls unless I give it about half throttle. I have adjusted the TPS Many times. I have 4.64 volts feeding the TPS, I have set it for the 82percent difference, and it idles about 2500rpm, The book also gives a number of 4.2 volts, but at 4.2 volts it idles high as well, I have changed this setting MANY Times, I just can't get it to run good. Trans shifting don't seem to be just right either. When I first got the Jeep back, it run like the timing was off, I ask my son if he changed the timing and he said No. I am LOST, PLEASE HELP if you can. Thank You for any Help, Bobby

This should help.

there is a frost plug there

After about 1962 or '63, pretty much no transmission had a second pump (was called a rear pump) which is why you can't push start an automatic car. Most pumps fail because debris gets into them from a failure elsewhere inside the unit, scoring up the face plate and gears, lowering pump pressure.
You likely have a bad seal, worn seal surface on a shaft etc that is causing you problems. At this point, best thing you can do is either do a complete rebuild or get another good unit.

books on 88s are hard to find
owned 2, 88s. French REnix, EFI, just plain old sux....
the TPS is near 1vdc at idle.(out pin)
it's just a POT. 5v /\/\/\/\/ground....
then
the output is the tap lug called throttle angle.
1v is par.
never 4v that is Wide open throttle, 100%
4.64v is power, spec, is 4.5 to 5.5v , 5v is perfect, its just a 5v power regulator in the ECU that runs external sensors.
that is good.
all 88s love to have the ISC stick when it sticks idle screams.
cleaned mine 100s of times. in 300k miles.
then used Siberian gun oil slick on it and ended that.
this gun oil dries and looks like fry plan TEFLON,
amazing stuff,
the stepper motor jams at the valve cone.
ever 10,000 miles on mine, even both brand new cars.... did.
back to TPS page in the service manual, I have.
real
quote.
"Throttle position sensor is nonadjustable. Only output
voltage can be monitored." (for errors, my comment added.)

that means its learned. never calibrated.

watch out for kids, they hear advance timing and 2x more horse power and they find out later the distributor
is injector sync, and takes a dealer DRB scan tool to set.
leave the distributor alone
the spark timing is carved in the side of the flywheel for ever.
and is not adjustable at all
and that CKP if played with, it is a buggger to re tune,!
its a dang 2 wire Faraday sensor with trick gap setting.

thats it for now..

could be low on fluid or could be the tps(throttle position sensor)

Reverse lamp switch wiring or switch itself is defective. Mounted on trans. Run slector lever over reverse with someone watching. the back.If yhey flicker the switch is bad. Work it several times sometimes helps .

I have a jeep wrangler and to have it towed you are suppose to put the transverecase in neutral after you first depress brake pedal put trans in neutral then start engine shift auto trans into drive release brake pedal make sure there is no movement, shut engine off with key left in acc position shift auto trans into park, disconnect neg battery cable (damage can result in trans if shifted into park while transvere case is in neutral with engine running) you should refere to your owners manuel

put it in 2 wheel drive a drive in reverse for about 5-8 ft and this should unbind it.......good luck!

Is it manual or auto trans? If manual the gear lube is thicker when cold and the syncronizers tend to stick and not slide free for grind free shifting or for locking into gear.
If Auto trans if the jeep is warmed up setting then cycle the gears before driving. If that helps then the fluid is not getting through the valve body properly. It could be metal in the body or filter or cold seals are letting fluid by til the seals warm, expand and hold pressure. I'm assuming trans fluid is good, not old. One item that can lead to poor cold shift in an auto trans is a bad torque convertor. Since it seems to be a second gear issue the second section of the trans could have a bad seal. In an auto trans I'd take to a shop and have a cold pressure test done. They will tell which one is the problem.

if you are getting fire to the plgs its not the cranksaft sensor...if you arent getting fire you need to replace it they are simple to replace on the jeeps. took my son 5 minutes to change one out