Engine or tranny?

[JeepXJ93]

Alright now i'm completely confused, since i brought my 94 out of the back yard where it sat for 4 months, i thought i'd have to replace just the battery b/c it wouldnt idle on its own, so i put an optima red top in it....solved my problem for about 20 minutes then it went back to stalling unless i kept on the gas. Now i've been driving it for the past 3 days, and it only has the idle problem SOMETIMES, the latest is....i'm driving back from the shop today, and its hesitating and sputtering, then in between feels like the tranny was slipping, then the check engine light came on, i didnt get a chance to read the code yet b/c i just wanted to get it home, buy the time i reached my street it was hesitating and sputtering so bad i was suprised i got up the street. Any ideas welcome, i'm going to try to see if i can get it to auto zone sometime tonight so they can pull the engine code i'm throwing. Thanks all

 

[Lawn Cher']

Did you put fresh fuel in it?

 

[1985xjlaredo]

Sounds like a TPS maybe. Try to unplug the TPS and see what happens

 

[Avanteone]

Sounds like a TPS maybe. Try to unplug the TPS and see what happens

X2. sounds like Throttle Position Sensor. See what code it is and report back.

J

 

[JeepXJ93]

Latest update, guys at auto zone came out to plug in and try to read the service engine light that i finally got to come on by driving around for 35 minutes...and then finally getting on it a little on my way home when it still wasnt on, then it comes on...so i got back, they said they cant diagnose an engine code from a 1994, only 96 or newer....i dont know if thats true or not but anyways....now i dont know what to do...should i just start replacing stuff and see where i get? Maybe i'll just pay the d*mn dianostics charge at a garage. Any other ideas welcome.

P.S....yea i filled up w/ fuel over the weekend. Which plug is the TPS...there are 2 near the throttle body, one of them i unplugged and nothing happened, the other i unplugged, it hesitated for a split second then continued idling fine, then when i plugged it back in it hesitated again for a second and then was fine as well.

 

[justin H]

hey man i had the same prob 2mnth's ago with my 93 xj an i replaced the tps an now it run's a hell of alot better, you can also try your crank position sensor, wich i also did.
the tps is 63$ an the same with the cps.
hope this help's

 

[Matthew Currie]

On a 94 you can read your own codes. Cycle the ignition key: on-off-on-off-on. (don't actually start!) The check engine light will now flash two-digit codes. "12" means you've replaced your battery within the last 40 or so starts. "55" means normal, end of sequence. Anything else is a code you shouldn't be seeing. You can get the meaning for most of the codes, which are pretty much standard Mopar codes, here or post back for more Jeep-specific information and hints.

 

[JeepXJ93]

Sounds good, are those tps and cps prices from jeep itself or is it ok to go aftermarket? Otherwise, thanks for that info about the codes!...i'll deffinatly give that a shot when i get home tomorrow. Thanks again!

 

[JeepXJ93]

Ok, so i tried the flashing service engine light to figure out what code i got, first i got a 12, then a 14, then a 55.....i just checked that link you gave me and it all makes perfect sense i think......12 is true b/c i did just change my battery to an optima about a week ago, 14 makes sense b/c i've been hearing some stuff about it possibly being the MAP sensor, and 55 is end of codes....i'm going to try to find where the map sensor is and replace it, is this a part that i should only get from a jeep stealership? Thanks again for the help!! I really appreciate it.

P.S...i just searched MAP sensor and didnt find anything to help me locate it and or how to replace it....anyone know?

 

[cyberbackpacker]

From the factory service manual:

"Manifold Absolute Pressure (MAP) Sensor
The MAP sensor is mounted on engine compartment firewall. The
MAP sensor is used by PCM to calibrate amount of air/fuel mixture
supplied to the engine. This sensor measures manifold absolute
pressure. Ambient barometric pressure is also measured when ignition
switch is first turned on, during engine cranking, and at wide open
throttle.
The MAP sensor transmits a low voltage signal (1.5-2.1 volts)
at idle when manifold vacuum is high, and a higher voltage signal (3.
9-4.8 volts) during open throttle when manifold vacuum is low.
Input voltage (from the PCM) to MAP sensor ranges from 4.8-5.
1 volts. Adjustments made as a result of this input will usually
affect injector pulse width, ignition timing, idle speed and upshift
indicator light."


It is on the center of the firewall, should basically be right inline w/the valve cover.

 

[JeepXJ93]

awesome, thanks for all that info, i didnt know it controlled that much....i'm replacing it in a few minutes, i hope thats the only problem! Thanks again for all the help/info.

 

[JeepXJ93]

unbelievable, so i replaced the MAP sensor whiched solved my problem, code 14 went away, i start it up, idle jumps to 2000rpm....i unplug my TPS, idle drops to normal 800rpms....plug it back in idle goes up to 1100, check my codes, and i now have a 24!...great, lol whats next.

 

[JeepXJ93]

Ok, here's the latest, i replaced my MAP and TPS, the battery was disconnected when i did this, when i reconnected it, i drove it for 5 minutes or so and then came home and checked the codes...for some reason i still have a 24...which is Throttle position sensor over 4.96V. So even though it ran perfectly fine and the idle was normal, i still have a problem or is this code something that just takes a little road trip to clear? If thats not the case and i have too many Volts running to it which was the cause of the first failure, how do i fix that kind of a problem? Thanks

 

[lawsoncl]

You probably caused the error 24 when you unplugged the TPS. If everything is running fine, disco the battery to clear the code and forget about it.