Question about 1988 Jeep Cherokee

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1988 Cherokee Pioneer 4.0 auto trans. 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 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 82% 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. 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. I am at the Beach and do not have most of my tools with me. Thank You for any Help, Bobby

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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....
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.
"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..

Posted on Mar 12, 2017

  • _-__-___-_
    _-__-___-_ Mar 12, 2017

    btw just left the beach, so you are my replacement, 30 days on the beach !
    85f every day , nice off shore breeze



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SOURCE: 1996 jeep cherokee sport 4.0 L it will stall

it looks like your engine is having an over rich fuel mixture maybe, thatswhy when you press the pedal to the floor it starts becouse you allow lots of air to help clean the mixture while cranking, also you should have black smoke in the tailpipe until it cleans up and runs fine, i think youre having a leak in one our more injectors you should check them first for proper seal under pressure these is done in an injector test machine, second it may be a defective map sensor these trucks some times have a bad map and dont give a MIL (malfunction indacator lamp) and last but more rare to be is a blocked fuel pressure regulator chek fuel pressure it should be between 38 and 45 psi and it shoul hold these pressure when you turn off the engine if pressure drops fast its injector seal problems or fuel pump check

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Im jealous! Im basically looking for that rig in the Suburban form. I already have a gas one of that year. The 4x4 stuff is the same regardless and yeah you have to stop to put it in four hi or four low. It is simplicity itself. Less to go wrong in the long run. I like it better then my mothers jeep.

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Hi. I have a 98 GCL too with the same issue and new H gasket too !

Fully charge battery. Then find the loose ground connector at the negative battery terminal. Remove nut and sand down corrosion on the connector. Reconnect, tighten nut. Check regularly. It's even free ! Good luck.
P.s bet you park on a slope at the bank.


Oct 14, 2012 | 1997 Jeep Grand Cherokee

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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,...

the tps is not adjustable,
its 1v at idle and 4vdc at wot
its not the TPS.,
it has 3 pins, its just a pot, (a variable resistors is all it is and is cruede)
1 pin is ground. 0v
one pin is 5v, (about) and is POWER> 4.5 to 5.5v typ
the output pin is 1v to 4v, as you advance throttle it does that 1 to 4 gradually.
end TPS , guessing, its autolearned each key on.
i see you are reading the wrong Jeep books, its a 1988 not 1992 to 95

we cant tell you all the tests, and if no tools to do them be silly to pretend you do.. on the beach.
but if timing is off its off. the crank flywheel markes are fixed so those cant be changed,
but the distributor is not spark timed its injector sync timed
so your guess, is wrong, but if was messed with its a impossible for you to correct it lacking a scan tool.

the only words you posted that help are
it starts to move, then give it a little more gas and it Hesitates and stalls unless I give it about half throttle. but totally left off does engine have full power at wide open throttle
if not
then the fuel pressure is way too low.
or cat melted.
or map sensor, vacuum port clogged.

Mar 12, 2017 | 1998 Jeep Cherokee

2 Answers

Where is the fuse for the tranny it takes off in 3 gear it is a 4 speed auto i blow a fuse or some thing thank you bob

The trans has a built in limp mode if it detects a problem. More than likely there is something else wrong,

Try to reset it first. Turn the vehicle on and off 3 full times and then start it and see if it starts out in first. If you then fell it lurch and go back into limp mode have it scanned to see. It could be the trans computer, a sensor or a hard problem internal to the trans. Hope this helps.

28 years rebuilding trans and factory trained by chrysler on that trans.,

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