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Another thread about TPS issues...

LockeXJ

NAXJA Forum User
Location
USA
Hello NAXJA. Sorry to bother you with more tech support about throttle position sensors, but I'm kinda stuck here. I bought my 94 XJ 6cyl/4.0 a few months ago and have had persistent problems with engine code 24. I used to also get the code for bad MAP voltage, but now its just the TPS.

I have been having severe bucking, at first only at high speeds but now even in first gear. The accelerator pedal occasionally loses all function, especially after coasting down my steep driveway in first gear. Then all of the sudden, it will start working again and the car will jump at an alarming speed. As mentioned before, it has been throwing code 24, but oddly enough the code doesn't come up until the engine is warm. Even when doing the key trick to check for codes, I've been able to get it to report no codes after some maintenance, but then they come right back after a few minutes of driving.

So here's what I've tried:
-cleaning grounds
-replacing vacuum lines
-replacing TPS (Duralast) ---- BTW, when tested I only got 3.5v at WOT, with the old one and the new. Is this normal?
-replace O2 sensor (Bosch)

Yet I'm still having problems, and I'd venture to say they're getting worse. So, do you guys have any advice as to what to try next? I know that my battery terminals and probably cables are pretty corroded so I plan on replacing those soon, but could that be causing my issue? Could it be a relay issue? I found one sitting at the bottom of my engine bay by the relay panel, yet the only hole it fit was for ABS, which I do not think I have equipped given that every other relay or fuse necessary for it is empty. Or could it be related to the wiring from TPS to ECU, and if so how would I go about checking that? I'd appreciate your input so I can get my Jeep running nicely soon!
 
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Testing the TPS you should be seeing about .25 volts at minimum throttle opening (idle), and about 4.8 volts at WOT wide open throttle. Bosch O2 sensors and Jeeps do not play well together.

Only buy genuine Jeep engine sensors, and NTK 02 sensors. Most auto parts stores sell cheap crappy Chinese made parts, some that even come with a "Lifetime Warranty". These parts are poorly manufactured and/or made from inferior materials. They are often out of specification, or even failed, right out of the box. The ones that are not faulty many times will have a short service life before they fail. Always buy top quality replacement parts and genuine Jeep engine sensors. Numerous threads detail long and frustrating searches for a "problem" that ended up being cured simply with genuine Jeep repair parts.

Cheap parts are cheap for a reason.
 
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Testing the TPS you should be seeing about .25 volts at minimum throttle opening (idle), and about 4.8 volts at WOT wide open throttle. Bosch O2 sensors and Jeeps do not play well together.

Only buy genuine Jeep engine sensors, and NTK 02 sensors. Most auto parts stores sell cheap crappy Chinese made parts, some that even come with a "Lifetime Warranty". These parts are poorly manufactured and/or made from inferior materials. They are often out of specification, or even failed, right out of the box. The ones that are not faulty many times will have a short service life before they fail. Always buy top quality replacement parts and genuine Jeep engine sensors. Numerous threads detail long and frustrating searches for a "problem" that ended up being cured simply with genuine Jeep repair parts.

Cheap parts are cheap for a reason.


Thanks for the reply. I searched for a TPS on mopar America for my 94 and got no results. Any suggestions on where to look?

Edit: Or could my local Jeep dealer carry them? It'd be nice to not have to wait on shipping.
 
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I bought a TPS sensor for my '96 H.O. from the dealership. I seem to recall it was new-manufacture and not just NOS. I also seem to recall that the price was pretty good, even for the stealership.
 
Testing the TPS you should be seeing about .25 volts at minimum throttle opening (idle), and about 4.8 volts at WOT wide open throttle.

Also check that you have the 5-volts between the sensor +5 volt line and the ground wire. Could be something dragging down the sensor +5-volts?
 
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