1g high idle prob when warm

[Talek]

I searched and couldn't find an answer. I've had this car for a few days now, 93 Talon TSi AWD, and noticed that when the engine is warm, at full operating temp, the idle starts climbing. It'll start at 700-800rpms when cool, but creep up to 1200 then even about 2000rpms at idle. The car supposedly has a new timing belt, but could it be a timing issue? TPS? I don't experience any idle surging, it's stable at whatever rpm it's sitting at. Thanks!

 

[TheCrazyDSM'r]

you may need to reset your TPS. I had to do that once. It worked for me but we'll see no won't we

 

[Talek]

How do I reset it?

 

[TheCrazyDSM'r]

let the car warm up because that is when you are having the problem. Then tighted the screw all the way down. Then slowly work it out untill the idle is where it should be. See if that works, let me know.

 

[Talek]

1 last question, where is the tps screw? I'm a bit of a noob..

 

[TheCrazyDSM'r]

, it is ok. At least you are learning.
here is a picture to help you find it. Just remove the little cover and get yourself a phillips screwdriver

 

[Talek]

Thanks! Now time to check it out.

 

[Talek]

Hrm, wasn't the TPS screw... It was already tightened all the way, and loosening it just raised the idle. :thumbdown Any other suggestions?

 

[turboholic]

Originally posted by TheCrazyDSM'r
, it is ok. At least you are learning.
here is a picture to help you find it. Just remove the little cover and get yourself a phillips screwdriver

-That's the BISS, Basic Idle Setting Screw, the TPS throttle position sensor is the black plastic thing below the BISS. To set the basic idle speed, you should also ground the connector on the firewall so the ECU knows you're setting the basic idle speed.

-Talek, try removing the intake pipe and clean out the throttle body to see if it help.

 

[japmaxTSi]

Same prob here the screw is all the way down.

When its up to temp idle increases to about 1800rpms.

So I'll try reseting the idle to see if that works.

 

[japmaxTSi]

Another thing I should note is that my screw is stripped so I can't turn it back out can I still reset the idle without moving the screw out?

 

[Talesin]

No. If your screw is stripped, it needs to be replaced (or carefully helicoiled if it's the threads in the throttle body). Not too expensive to replace, even from the dealer. Replace the o-ring at the same time.

What does your vacuum read at idle, assuming you have an aftermarket boost/vac gauge installed and tapped from the manifold. Most likely a vacuum leak causing the problem.. our cars *should* idle at 18-20 in/Hg at sea level. Lower with upgraded cams.

And when you were adjusting the BISS, did you remember (1G specific) to ground the timing set connector on the firewall, and the pin on the ODBI/ALDL connector before you started playing with it? Have to do that or the ECU will attempt to adjust the idle at the same time to keep it steady, leading to problems. Mostly ask that as if I remember correctly, backing the BISS out should lower your idle RPMs, not raise them.
See VFAQ for specifics (which exact pins need to be grounded) on how to set your base idle (and timing, if you haven't checked it personally) on a 1G.

 

[japmaxTSi]

I haven't worked on my car just yet but to clear some things up. Since the idle increases gradually on startup while warming up to temp and stops at a high 1800rpm does this mean the TPS is functioning properly and isn't set correctly? meaning the TPS is moving at an incorrect position.


A vacuum leak would increase almost immiedietly and not gradually as the car warms up right?

I'm heading to the dealer for the o ring and screw today. My 1g tsi wasn't taken care of properly from the previous owner. This is my first DSM and I'm fixing little things like the fpr hose routed incorrectly with a couple of other hoses and wires in the wrong place. No biggie it keeps me busy after work, I enjoy the challenge. The car huals ass just to list a few mods I have 6bolt, evo 3 16G turbo, Tubular mani, MAFT, 3" exhaust, etc. etc.

 

[romeen]

...backing the BISS out should lower your idle RPMs, not raise them.

Backing the BISS screw out will RAISE idle since it will allow more air into the engine (diverted around/past the throttle plate).

Increasing idle as engine warms up brings to mind two possibilies:

1) Malfunctioning FIAV
2) Throttle cable adjusted too tight

Read this post for more info regarding the throttle cable (pay particular attention to third sentence of 1st paragraph):

http://www.dsmtuners.com/forums/tuning-engine-management/241449-tps-reading-idle.html#post151021480

Do a search on FIAV as there are a lot of threads on it.

Good luck, idle issues can be frustrating.

Also, if you discover air leaking past the BISS screw, you can replace the o-ring with a 1/4" o-ring (easily found at most hardware stores). Put a dab of grease on it and re-install BISS. This o-ring will be slightly larger than the stock one and will completely seal the BISS screw and prevent that small annoying boost leak.

 

[boostcrazyawd]

I had the same problem with my car and it turned out to be the fiav, which i just blocked off and it idled perfect. basically when the motor is cool it lets more air by but then coolant warms it up and closes the valve. When it fails it stays open when the motor is warm and it idles high.