TPS adjustment

I have a '98 TJ with a 4.0. I have some intermitent high idle problems and power surging at partial throttle. I think it might be the throttle position sensor. For $40, I'll give it a shot. When I install it, do I have to adjust it? Can this even be done on newer 4.0's? I've read how to adjust renix ones, but not mine. Anybody know? Maybe it just needs adjusting, not replacing.

I'm 99.9% sure no adjustment is needed.

Are they notorious for going bad or something?

CollinM said:

I'm 99.9% sure no adjustment is needed.

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Renix TPS is adjustable, '91-later Chrysler system is not.

It's really simple but easy to mess-up if not done in the proper order with regard to throttle plate adjustment and closed IAC position.

For auto transmission, you basically measure the input reference voltage and adjust the output signal voltage to about 83% of the input at idle position. For auto I think it's the square 4-plug connector with only 3 wires used. Oh yeah, gotta use sensor ground and not vehicle ground for this measurement too. It's the brown wire in the connector, me thinks.

Best to adjust HOT idle with IAC fully closed via throttle plate before adjusting TPS.

They are an electro-mechanical device so eventually they fail but should be good for 100k miles plus.

Well, the Renix(87-90) ones were notorious for failing after they got wet. I honestly can't tell you a whole lot about the High Output ones because I am not constantly working on one. I'm assuming you'd be able to pull a code if it was bad wouldnt you?

Geez guys, I'm so sorry but my eyes are playing tricks again and reversed 98 to look like 89 when I read OP. Please ignore my waste of time and yes, you should be able to pull TPS code from that rascal.

Well, there's no code, so can I assume that's not the problem, or could it just be intermitantly bad, just like the problem?

XJXJ said:

Geez guys, I'm so sorry but my eyes are playing tricks again and reversed 98 to look like 89 when I read OP. Please ignore my waste of time and yes, you should be able to pull TPS code from that rascal.

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Heh heh.:doh:

Cjmartz2k said:

Well, there's no code, so can I assume that's not the problem, or could it just be intermitantly bad, just like the problem?

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It could be an intermittant problem. I don't know whether that system stores codes or not. I guess I'll turn it over to someone who knows more now.

Cjmartz2k said:

I have a '98 TJ with a 4.0. I have some intermitent high idle problems and power surging at partial throttle. I think it might be the throttle position sensor. For $40, I'll give it a shot. When I install it, do I have to adjust it? Can this even be done on newer 4.0's? I've read how to adjust renix ones, but not mine. Anybody know? Maybe it just needs adjusting, not replacing.

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here ya go. Could be the TPS, but ususally you'll get a code right before (30min) it finally fails completely. Now...should this be your problem, pick up a spare just in case.

They HATE water....thats why I rarely clean under the hood anymore...if I do..I cover the whole TB.

in your year they are non ajustable. good luck.

BTW...FWIW I've lost 3 in the 2 yrs I've owned my XJ.

Well since we're on the subject, does any one have a FSM (factory service manual) or link to one for how to adjust the TPS on a 90 XJ. Just chnage to a bored TB and need to dial in the TPS.


Bob

Thanks guys, I'll replace it today :wave:

Cjmartz2k said:

Thanks guys, I'll replace it today :wave:

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Hope it helps your problem, let us know.