This happened before I broke my TPS and had to get a new one, but since I got the new one and started to play around with it, it has begun to bug me. When the engine is warm, and the lights are on the "OFF" mode (the lights pop up, but are dimmer) the idle would be really low (around 500, 600 ish) When I put the breaks on, the idle drops ever so slightly maybe to 450, 400 or so, the car shakes and seems like it'll stall any minute.

Now, i usually put the lights in the second setting, where the lights go down, and the fog lights/turn signals light up. In this condition, the idle is normal, at around 800-900. When I put the breaks on, same thing happens, idle drops, down to maybe 600 or so, then comes back up slowly.

I'm thinking this is some kind of electric problem, because the lights would give the tps a voltage boost? And the break lights coming on would then cause a drop in the voltage because of the added resistance? I have no idea...

Also, i've tried to adjust my TPS to whats described as "in range" and all that does is make the car idle at like 200 rpm.

 

mod list?

 

Car's pretty much stock, except for a BOV, and new foglamps. (came with the car when i bought it.)

 

Any help?

 

Adjusting your idle screw that is on the other side of the Throttle body of the TPS will also change your TPS readings. But if you are ''in range'' next step would be to fix your idle, which the only thing you should be messing with at this point is the idle screw under the throttle body underneath the intake.

 

Oh! Yeah that would make sense. Thanks a lot. I was adjusting the TPS since it was the only thing I touched, and I thought that IT was what was wrong. I guess it makes sense to adjust the idle screw.

 

The idle problems are pretty much fixed now, but I still dont understand the voltage issue. It STILL goes down when i push on the breaks, and there is definitely a difference with the lights off and on.

 

Also, I noticed the idle goes down when I turn on the rear window defrost and the A/C. I thought the idle was supposed to go UP when A/C is on to keep the car from stalling. But in mine it goes down, so low that the car shakes and studders as if it was going to stall.

 

just some quick notes

1st-Recheck and make sure your TPS readings are in range after its reached normal operating temperatures.
2nd-check your IAC valve underneath the intake close to the firewall and make sure its pluged in nice and tight and that its working properly.

i would allso check to see if the computer has any faulty codes stored in it.

 

I've read about it in the FSM, but I'm not sure exactly where it is, could anyone possibly provide me with a picture of it? And how am I supposed to check if it's working properly? I know it says something about an ohm metre, but it doesn't really give too much detail, is it as simple as sticking the leads of the metre into to IAC?

 

Are you able to check the battery voltage at idle, with the lights and other accessories on, and then compare it to the voltage at idle with all accessories off (lights, AC, rear defroster etc)?
Could it be that a low voltage (caused by a current drain such as lights) is affecting the voltage read at the TPS or other sensors?
Or perhaps your ground wiring to the battery is poor and inducing a votlage drop?

Just seems strange that anything that places a load on the electrical system is causing the idle to drop - I doubt the ECU would have any different behaviour if lights are on or not, so I would guess it's a battery/alternator/wiring issue.

 

Yeah, I measured the voltage at the TPS during idle with lights on and off. It's really odd, I only measured it from the second from the top wire, and only bothered with the closed voltage, because WOT voltage is the same, regardless. Here are my results:

LIGHTS OFF: .54V

LIGHTS ON: .89V

 

Hello?