why does my celica run better with tps unplugged???? Options

[replica250]

hi every one, i got a question
why does my car run better with my tps unplugged?
my 3sge has a wimpy cold start and suffers from an iratic idle, fine until it comes off cold start at the point my temp needle reches just under half way.
on cold start it will start first time but just sit at idle then if left for around 20 30 seconds it jump up to 1500rpm and happly sit there untill its warm then the idle when warm will dive to just above 600 rpm and car will shake but after 10minutes worth or driving itll settle.
anyway i forgot to plug my tps back in after working on car saturday and i fired up the car and it started perfectly and drove fantastic and had super throttle respone, only down side was it hunted on idle
only about 300 to 400 rpm once warm
so whats the deal? why does car run better once tps unpluged????

[Smaay]

could be your idle air control valve. but running with the TPS unplugged could be bad, the ECU needs that information for enrichment

[richee3]

Bad TPS sending the wrong signals, maybe? Reset your ECU and check for codes again. If you get a TPS code, you know something is fishy.

[replica250]

i seem to be contanly resetting my ecu, and cars never chucked a code even when i was driving with the tps unpluged it never even iluminated the engine light, just ran fantastic, i only relised as i went looking for the cuse of the slight hunting then sore it was not plugded back in, think ill just unplug it again
cars never ran right in the first place

[stephen_lee]

does the CEL come on with the engine off, and key in run position?

[Rusty]

reasons for a low idle, check in this order (as they are the most likely to have caused the problem)

water temp sensor circuit EG-199
idle speed contol valve EG-259
vacuum sensor circuit EG-196
in the ST202 3S-GE repair manual found in the above sticky with those page numbers

[replica250]

does the engine light come on when i put key on to acsessory and run, yes along with all the other dash lights ikons but abs goes out as it should and the engine light goes out after key goes to start when i start the car and stays out.

[replica250]

So is that right for the engine light. Not on on accessory, on during run and off as soon as car starts

[richee3]

Yes, that's right. It comes on to show that the ECU is getting power then goes off when the car is started, unless there is an issue. Do you have a multimeter to test your TPS?

[replica250]

I do in deed it lives I the boot of the car

I do in deed it lives I the boot of the car

[richee3]

Excellent here's a very useful how-to for adjusting your TPS. There are huge differences between our cars and the IROC's that this how-to is for. For starters, out TPS's are pretty much set and not adjustable. They can be moved slightly, but not enough to make a huge difference. This how-to tells the voltages that you should see when you test your TPS though, and when I tested mine, my voltage was spot on with this how-to.

http://www.iroczone.com/2009/10/adjusting-...ion-sensor-tps/

As for wires, we have 3 on our TPS. One is power, one ground, and one variable voltage wire. That's the one you want to test. Ground should be brown, power is black with red if I remember correctly. I'm curious to know what voltage your TPS is putting out.

When you unplug your TPS, your ECU reverts to a "safe" map that should theoretically be worse than of your TPS is plugged in and working properly. When the ECU is using the safe map, it runs rich and cuts down on power. I recently had a similar problem to yours. My car was going lean at 3,000 rpm and bogging. When I unplugged my TPS, it added fuel to run rich and in doing so, kept my air fuel ratio from going too lean and bogging. If I had to guess based on my experience, your car is running lean for some reason and the enrichment is helping smooth things out.