Setting TPS when COLD
 

I cant find this anywhere. Yeah, you have to have a RUNNING car to set your TPS. My car doesn't run anymore. SO how do I set my TPS? I was trying to adjust it so I didn't run 10:1 at idle, but now the car won't start anymore. I was adjusting the TPS and the idle screw on the other side of the throttle body.

I took the throttle body off to check if the primary was open enough per the FSM.

Tried searching also. Almost did the TB mod but apparently that's useless for a street car.

91 turbo.

Thanks

you have to bypass/hold open the thermowax, since it pushes on the throttle, the throttle isn't at zero...

You can't set it right cold as the computer reads a different voltage warm vs cold

And, IIRC, the TPS does nothing with a cold engine, only when its warmed up

what he said. you can't set it cold.. UNLESS you hold the thermowax valve down.. so the cam isn't pushing on the throttle shaft...

familurize yourself with the thermowax system, and it will more clear were you need to jab with a screw driver.


your tps isn't the reason your car wont crank.... you may have a lumpy idle the more it warms up but it won't keep it from cranking, .. you can even crank with it not plugged in... being that you have a turbo model, and you are modding it, it's probably low compression. just gonna toss that out there.

Does it matter what the ecu sees though? I kinda assumed the tps plungers essentially changed resistance when they move in or out - so what you're measuring is where the resistance is corresponding to where the plunger is.

So I rebuilt the motor myself, drove it from seattle to oregon, drove it from my wedding, drove it probably 500+ miles. It was idling super rich so I was trying to adjust the TPS and idle to make it better. Now the car won't start. And it's not really modified. The only thing that's really been modified is full exhaust and some emissions removed. Other than that it's a nice clean stock build.

sure, but the throttle is not closed when the engine is cold.

Ok so next question, If I completely remove the thermowax, since the throttle is now completely closed, should the car start without me giving it throttle input? I see there's a small hole in the primary plate. Is that enough to get the motor started? Or should I just remove the thermowax, test the TPS and then put it back on?

why not just move the thermowax out of the way, set the tps and then start it? why do all this extra work?

You can place a large rubber cap on the upside down screw which will force the linkage downward which will replicate a warmed engine.

OR, since we're dealing witha no start engine, check the essentials, compression spark and fuel

Or you can read the whole thread.

I took off the thermowax and was able to set tps. If you do this you need to take off the plate with the two dash marks on it or else it will bind and make your throttle stick.

It was only two screws to remove the thermowax. Not too big of a deal. Since there's no coolant going to the throttle it was a better idea for me to go this route. Previous owner disabled the cold start high idle function anyways.

only 2 screws...? i can poke the cam with a screw driver and hold the bitch outta the way. which is by far a faster method. i'm not saying the way you did it is wrong.. but advocating it being done the long way is senseless.

But then you have to prove two wires and turn a screw while poking a cam. To each their own I guess. Like I said, it's useless on mine since there's no coolant going to the throttle body.

Both my thermowax units have three screws.

I assume you are using the voltage method to adjust your TPS? If so you should be able to do it cold. I didn't know my thermo wax was bypassed and was still able to my TPS. I then reset it once I hooked everything back up.

I have read the whole thread, theres been no reference as to what the compression is, if theres spark, if theres fuel, or if you've checked any of them. Just because its freshly rebuilt doesn't mean something didn't happen internally, or something electric isn't working right

since you had it running, drove it, and it quit running, it sounds like engine wise something happened, but being your so dead set on the TPS being your problem, which has nothing to do with cold starting, have fun chasing, I added my thoughts

It was tps. I've never heard of a motor blowing while itS idling.

I have seen it.
Failure to properly bevel the closing edge of ported irons collapsed the side seals.

Someone please confirm that you still have to make sure the throttle plates are closed, doing the voltage method. So either the engine has to be warm enough for the fast idle cam to release, or you have to release it (I prefer using the screwdriver method).

Either method of setting the TPS requires the throttle plates closed to their normal, engine fully warmed up, idling position.