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Bad luck with TPS sensor.

L

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NAXJA Forum User
Location
Albuquerque
well when i first got my jeep the TPS sensor went out and i had an hard time figuring out what was wrong, well i found out that it was the TPS sensor so i bought one from autozone it worked fine for about 2 months then started going out well it came with a three month warrenty well after fighting with the manager to give me a new TPS now 7 months later this new TPS sensor from autozone is acting up.
Well when i start up my jeep it will rev up then it will die if i don't give it any gas, but it idles after just fine.

Has any one else had this problem with there TPS?
Is there an better one then an autozone peice of shit?
i'm sure i could find one at the dealership if i wated to pay an high price for small peice of black plastic.

It's an 1991 xj, 4.0 H.O.
 
well the reson i think it the TPS is because the autozone TPS is not he best of quality, well the problem went away when i got a new TPS sensor both times.
How could i check to and see if it was the IAC?
thanks for the input.
 
From what I've read/seen, the TPS is just a variable resistor/potentiometer like a stereo volume control. If you still have the original, perhaps you can open it up carefully and look to see if the wiper in it has made bare spots, and/or spray contact cleaner in it. I know higher end audio places carry sprays just for cleaning the insides of volume controls.

If you put an ohmmeter on it while disconected, it should increase/decrease resistance nice and smoothly as it turns. Any jumpy motions on the meter would be bad spots or dirty / oxidized spots. Focus on the low end where it sits at idle.

You could do that to the new one too, but you'd have an even harder time returning it then ;-)

Skip
 
skipc said:
If you put an ohmmeter on it while disconected, it should increase/decrease resistance nice and smoothly as it turns.
Click to expand...


Ah, that's not the correct way to test it. It requires a voltage source to return a reading. A TPS has a 5 volt input, ground and a output. You want to turn the key to "on" and back probe the output and ground. Slowly open the throttle and observe. Also back probe the input and ground to make sure that your getting 5 volts of input (or close to it). Purhaps there is a bigger problem going on such as too much input voltage. That is then frying the sensor.
 
bottleworks said:
Ah, that's not the correct way to test it. It requires a voltage source to return a reading.
Click to expand...

E=IR so it's the same thing, only you can test with an ohmmeter off the car. I believe I saw a resistance spec for it somewhere. If it's semiconductor inside (highly unlikely) then no, but it's not from what I've read.

On car you also test the harness and reference voltage the other way, but if you wanted to test the old one on the bench you'd need a fixed supply otherwise.

This test is focused more on the quality of the sensor rather than it's adjustment on the car. It's probably a lot more likely the wiper has worn something than the whole thing opened. And if you can open it up, you could probably try fixing it - at least that's what I'll try when it's time ;-)

I did this on some of the first generation GM sensors where needed years ago...
 
the TPs sensor from autozone is $30.00 bucks or so. well i think i'd be better off with one from the dealership.i think i'll just try and clean it, i don't wanna open it up.
thanks for the input.
i'll test it before and after i clean it.
 
The biggest reason tps's fail is power washing the engine. Water gets in around the shaft and corrodes the contact/wiper. Cleaning the outside of the throttle body with carb cleaner is just about as bad.

If you open it up and clean it, you will need to recoat the whole assembly with a waterproof pot lubricant before reassembly. This is not readily available outside the electronics industry and hard to find inside. In theory it should work if the damage isn't too bad, but I have never had time to spend on reworking one. I just pick up spares any time I'm at a pull-n-save yard.
 
30$ thats all when I got a quote from knecht's in portland they said $120
funny thing is mine was smooth and stuff untill full throttle then it went from 3.24 ohms to 6 and at idle position I have gotten a diffrent one off of a 87 and it is 2 ohms full and 6.5 ohms idle
 
$30 bucks not bad, but you pay for what you get, last time i went to an pull it yourself yard they only had one jeep and it was an older jeep 1987-1990.
whats nice about xj's 1990 and under is the fact that you can adjust the TPS sensor.
I'm not nor do i plan on taking the TPS Sensor apart, í'll take it off the TPS clean the 3 prongs on the sensor and then clean the Throttle body itself, this has helped in the past some what.
Thanks for the input.
 
I have taken mine apart It has a plastic circuit board looking thing in there and 3 little metal brushes that rub on three diffrent sections side by side I guess thats how they did it then was kinda cheap looking to me
 
Did you take it apart from the back or from the side with the shaft in it? Any tricks?

I've seen sprays for restoring/cleaning volume controls that should work to clean things up. It should also not show worn spots on the wiper paths. How was yours?

There really isn't much to them. I'd be interested in hearing how you got it apart, how you might recommend reassembling, and if you had the auto trans one or the manual one.

It might be a whole new procedure for TPS problems ;-)

Thanks.
 
Some one need‘s to make a TPS sensor that works better then AutoZone's. has any one bought one any where else?pepboys, checker? Some where other then the dealership.
mopwr2u did you fix your or just take it apart?
 
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