I need help...

OK guy's I need help. I am about to go crazy. Here goes the story.

About a month ago my 99 XJ 4.0 started to throw a code ststing that the TPS voltage was high. After that the Jeep started to Idle high when in park (about 2000RPM). I figured OK TPS needs to be swapped. Went to AutoZone and got a new one......... Problem went away............ for a week. Started to throw the same code and idle high again. Swapped the TPS again..... week later same thing. I then started thinking IAC.... changed that and still high idle. Changed the MAP.... same thing. I started digging in the search and found that the clockspring and the TPS share a common ground to the ECU and can send the same code I was getting...... unplugged the clockspring and nothing. Then I started thinking OK crank sensor..... changed that.... shame thing happening. NO VAC LEAKS EITHER.

Here is where it gets strange. I figgured I better get back to the basics and check my fuel..... everything is fine there.. pressure is good to the rail and the injectors tested fine... Then I figgured spark.......... BINGO..... I had put in a Sceemin Demon kit a while back and the coil was totally coroded on the end. I put my factory coil back in and it idled great and drove fine. I then went ahead and replaced the wires, cap, rotor and plugs....... Everything ran so good............ untill yesterday.

I went to Moonrocks yesterday and played around got home shut her off and went to bed. Woke up today and guess what ....... HIGH IDLE WTF!!!! Took it for a spin and it throws the TPS voltage high code and at WOT it just boggs down and top speed up hill in about 35MPH.

I am sooooooo at a loss here. Maybe CPU.... IDK???? If the wire was bad to the TPS wouldn't the resistance cause low input to the TPS not high? I also cleaned the cam sensor. It almost feels like the timing could be jacked.

Any help please!!!!

If the ground wire is bad, it would cause the signal voltage to be high. Grab a meter and measure the resistance of the ground wire to the battery neg. If its high, splice in a new ground wire.

Bump........... Ground tested OK. Any other ideas????

the harness at the back of the head can get chaffed and it may have damaged a wire causing this. did you unplug the clockspring at the back or under the airbag. i had a wrangler yesterday with the same code, and a speed control switch high code yesterday. and when i unplugged the clockspring under the steering column bezel, the code could be cleared, and it ran fine.

jneary said:

the harness at the back of the head can get chaffed and it may have damaged a wire causing this. did you unplug the clockspring at the back or under the airbag. i had a wrangler yesterday with the same code, and a speed control switch high code yesterday. and when i unplugged the clockspring under the steering column bezel, the code could be cleared, and it ran fine.

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When I unplugged the Clockspring under the airbag it was still running like crap.

I think I may have a bad head gasket. The coolant is rust colored and there is a milky substance in the oil through the dipstick. I am going to go drain the oil and have a look at it but I think this all just got much worse.:smoker:

adjust tv cable?

if you removed the airbag to unplug the clockspring, you didnt eliminate it from the system, just the airbag. you need to unplug it at the other end where the harness connects to it under the steering coulmn trim bezel.

jneary said:

if you removed the airbag to unplug the clockspring, you didnt eliminate it from the system, just the airbag. you need to unplug it at the other end where the harness connects to it under the steering coulmn trim bezel.

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Yah I had the whole airbag out and on the bench then I unplugged both harnesses from the actual clockspring as well.

R_jeep said:

adjust tv cable?

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Not sure what tv cable is?

throttle valve cable

R_jeep said:

throttle valve cable

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Ahhhh checked everything TB related and it is all fine. I have replaces 4 TPS's as well and 2 IAC's and one MAP just to be sure.

Quit replacing parts. Use a voltmeter to check them out. New parts can be bad too. You might be putting on new bad parts and complicating your problem so that you'll never figure out whats wrong. You should always be able to tell if a part is bad or not with the possible exception of the PCM which takes special equipment to fully test.

Your oil situation sounds (very) serious, but it should not cause high idle. Did the 4 TPS's and 2 IAC's and the MAP test bad? What about a vacuum leak somewhere to the intake manifold? This is a common cause of high idle.