Possible TPS problems

[Will]

I have come to the conclusion I am having TPS problems, sometimes the revs stay up around 2000 and the only way to fix it is to reset the ECC by quickly turning the ingnition off then on. I have a new Motorcraft TPS and when I set it at .9v throttle closed, I get 5.22v at WOT. Does this sound wacky. I have searched for vacuum leaks and could not find any. I also throughly cleaned the IAC and blew it dry with compressed air. I don't have any curb idle problems at all. And cold starts are just fine too. Could my new TPS be faulty also?

[SVOeric]

that sounds a llittle high on the high side --

you need to test the TPS with a analog test meter, and slowly move the throttle-- and watch the needle -- if it doesn't sweep slowly across the range, replace the tps.

[rkyrdrcr]

tps

I was having the same problem. I checked the tps voltage digital meter and also made sure it didn't jump with an analog meter. The iac was new and I cleaned it anyway. The problem did not go away until I went ahead and replaced the tps.

Richard

[jayG]

My guess its the computer. My car does the same. Im gonna put a LA3 on it tomorrow so I'll let you know the results.

[Will]

I used an analog to check the voltage sweep, and that was fine. But I use my digital to check closed and WOT voltage. I hope its not my computer, I am running the LA3. I had this problem before the LA3 swap.

[GAboySVO]

Will,

Did you put a new TPS gasket in when you swapped the TPS? I think you should be at less than 5.0 V at WOT. You might check the voltage coming through the connector from the EEC to see what you are getting there.

The symptoms you discribed sound like a bad TPS. I'm using one from Autozone on my '86 and it seems to work fine.

[Will]

Gasket, what gasket.

[GAboySVO]

Will,

There is a little gasket that goes between the TPS and the throttle body. If you get a throttle body gasket, it come in a kit form from Autozone and includes the gasket. I don't know that it is critical, but it seems to me that it would help keep crap out of the TPS potentiometer.

[Will]

Mike, I have a Fel-Pro throttle body gasket set with IAC, TB, intake upper and lower and other assorted gaskets but nothing that looks like an TPS gasket. Driveabililty seems to have improved somewhat since I adjusted the voltage to .97v throttle closed and 4.57 @ WOT. I am going to see if I can find a TPS gasket or make one.

[jayG]

Just put the LA3 in.. the car cranked up dead on 1K. I'm gonna take it for a test drive tonite, let yall know how it does(the idle) under driving conditions.

[turbizzy]

I have come to the conclusion I am having TPS problems, sometimes the revs stay up around 2000 and the only way to fix it is to reset the ECC by quickly turning the ingnition off then on.

I had the same exact problem a while back. It'll do it intermitantly huh? It still will do it sometimes but rarely since i "fixed" it. I think its your IAC. Make sure its cleaned out. You might want to reset your base (IAC disconnected) idle, then set your TPS again.

If its still doing it, mine turned out to be that the connector where the harness plugs into the IAC is like loose or something. You can literally move the IAC by pushing the connector up and down.

Just do this before doing anything!!!: when it does it again pull over and put the ebrake on. Open the hood (with engine still running at high idle) and play with the IAC connector. I mean wiggle it, push it in, tug on it, wiggle the wires (TPS and IAC) and see if any and which one makes the idle change in any way. Then let us know.

[Will]

turbizzy, that sounds like a good ideal. I will try that. I swapped out IAC to one I picked up from my day of dumpster diving at the local junkyard. But the connector maybe vibrating loose. Is there any way to test the TPS harness?

[turbizzy]

Is there any way to test the TPS harness?

I simply meant test at the connector to the TPS

Here's the link for setting your base idle and TPS, by testing the wires mentioned here its the same as testing the harness.

Im like 98% sure its your IAC though, if your situation is like mine was.

Try what i said, its more accurate as far as narowing down the possibilities of sensors involved or you can try setting your base idle (if not done so yet) and see if itll do it again.

izzy

[jayG]

Well so far the idle has done great! Its nice and steady, no more bouncing but I've only logged a/b 20 miles.So my original computer was the problem. But one thing's for sure, she's quicker and more respondsive. A noticeable difference for sure and it was a much easier swap than I thought it would be. I highly recommend that upgrade(LA3).

[turbizzy]

question for JayG

JayG,

Hey when i did my LA3 swap on my 85, i don't think i felt a huge difference besides the point that on my old ECU when the car got hot it would miss at idle and not anymore. But as far as power goes, ill be honest, didn't really notice a difference. BUT!, on slick pavement now when i take off under boost, the tires squeal a whole lot more than they use to before, must be the added torque and such. Ill run it at the track soon and post. Course i want to add the needed ACT sensor, ill probably drill and tap the upper intake where that flat spot is on the outsite elbow. Did you add the ACT to your swap?

Any luck Will?