onetinyr

ok here's my problem. i'll set my tps and make sure it's perfect. no cold start so i don't warm it up. i'll drive it for like half an hour and it'll be ok. and then little by little my idle will die down. until the car dies at idle. i'll take my ic off and the tps will be like 0.5 ohms. i'll reset it and it'll happen all over again. i noticed my o2 sensor isnt hooked up so i'm gonna take care of that today. but will that be enough to cause that much trouble. if now what else could it be? also after i reset the tps with the car off do i jump the coupler? i mean before i start the car again? and then remove it? my timings dead on and i dont have any emissions or acv egr so it's not any of those things. i also have a tb mod. any help is much appreciated in advance. thanks alot.

HAILERS

Setting the TPS has little to nothing to do with setting the idle. Download the fsm at http://www.ilunmyrx7.com and download the Fuel Section for your model to adjust the idle.

The slight variance in the tps setting could be heat expanding the metal parts in the throttle linkage.

Idle is set with the initial set coupler installed(nulls the bac, so to speak), fully hot engine, timing set, tps set, and then adjust the bac's screw and maybe the variable resistor if you have a 87/88.

HAILERS

O2 sensors are not involved at idle.

onetinyr

im not arguing with you but i have a fsm. and yes the tps does have alot to do with idle. if you advance or retard the tps that will greatly affect the idle. i know all about advancing fuel mixture and using the bac to lower idle. that's not my problem those are set where they should be. my problem is when i set my tps it idles fine. then it resets itself and doesnt idle at all. i know it's doing this because i check it after i drive it and see it's resetting. i dont wanna argue with you or seem know it ally or anything. this is just what i know and what i've figured from my car working on it. i just wanna know if there's anything i should check that would make my tps reset itself? i'm not throwing any codes from the engine so i can't figure out what the hell it is.

onetinyr

also i think the o2 has something to do with the lean rich mixture of the car which would also throw off my idle

HAILERS

What year car is this???? I'm just your basic series four person. I do agree if you really turn the tps screw to extremes, it will effect the idle, but with mine set at a output of one volt, it runs just fine at idle, and I can play with it and turn the screw say two turns either way and the idle stays in place. But then again, you've played with your car and it does effect your idle.

At idle, the 02 sensor is out of the loop. No effect at all. Stickin with that statement to the bitter end. humor.

There is a checkout of the tps, and its in the manual. The one thing they do not mention, is to look at the resistance on a meter, and then slowly move the tps through its full travel. You'd be looking for *opens* as you moved it through its full travel. Not good to have opens.

onetinyr

yeah i have a series 4 t2. i agree with you that the o2 does nothing at idle. i noticed that if i pushed my car and then let it idle it would throw a 5. so i know that after it's under boost the ecu will pick up on the o2 not being connected. on the same note like you said i can turn my tps screw either way and it wont mess it up too bad. but when it resets itself it goes to like .5 volts instead of the normal 1.0 that's when it messes the idle up. after i reset it it goes back to normal but then it'll reset itself again that's the problem im having. thanks for the help anything else you can think of?

HAILERS

No helpful thoughts here. If its a series four, and the tps was set with the engine HOT, at approx one volt, and then sometime later it reads .5volts, I'd say something in the throttle linkage is keeping it from returning to the same spot each time

Might be a thermowax problem. EAch morning I lood at my tps(well not each morn) and with the car cold, it reads 1.90volts. As the engine warms up, the figure decreases until it gets to where I set it, one volt, give or take .05 The reason it changes is because the throttle linkage is riding on the fast idle cam which is being controlled more or less by the piston on the thermowax. When the thermowax falls of the roll pin....walla, 1volt.

Defying most methods, I set my tps with the engine HOT and the engine at a normal idle. Note the manual says at idle the reading on pin 2G(tps output on the ECU).

Not much to say about the tps. Its got a reference voltage on the brown/white wire of four and a half to five volts, a ground on the brown/black and a output on the green/red wire of approx one volt at idle. Series four.

Yep, if the 02 has a open it'll kick a fault code. I've seen it do this while cruising at 70 and I can feel a very slight differnce in the engine when it does that. I got rid of that sensor some time ago. The fault would go away if I goosed the engine but it'd reappear wihin the hour.

onetinyr

well it's not the cable i checked that and made sure the clearance was ok. also it can't be the thermowax because i removed all the cold start stuff from my tb. so there is no piston thing there. i've read that with no cold start you can set the tps when it's cold so that's what i've been doing. looks like i'll have to try again and see what happens. thanks for the input hailers.

Cwaters

To be clear, are you saying you're adjusting the TPS when cold then warming the motor up and it's drifting out of adjustment?
You need to set the TPS with the engine warmed-up. If you set it while hot, it should return to the same settings when it warms-up. Mine returns VERY different resistance readings when it's cold...

Cory

onetinyr

i dont have cold start on my car so i figure that you can set the tps with the engine cold. that's also the write up on fc3s-pro.com. but if i'm wrong let me know cuz then that means that definately is my problem. thanks

onetinyr

bumpity bump bump

HAILERS

Kabump

onetinyr

bumpity bump no one else?

COsborne

Mine did that **** too... Pisses me off "right good". Pisses me off when people simply cant understand that you do not HAVE a fast idle cam. The only thing I can suggest is to make sure your tps isnt moving. Sometimes there is some slack in the casing. Ive heard the spring inside can stick as well. Another common problem is the throttle cable/omp linkage. Hope that helped. WD40 the hell out of all of it and let me know if that helped.