High Idle

[Caleb W.]

Hi, I'm new to the forums and seeking some help. I have an 84 T Type that has a bunch of issues, mainly electrical, but I'm trying to tackle one at a time. First of all the car is my step dads. Him and I are making this our project car. We are both fairly familiar with turbo Buicks. We've had this car for 7 years and we've both learned a lot. I'm really starting to get interested into making this thing run correctly. Yes I am aware that hotairs are difficult to work with but I'm up for the challenge and so is my stepdad.
Our main issues right now is a high idle once warm. It fluctuates from 1,000 to up around 1,250 and doesn't stay steady nor dips down to normal. It has an 87 ECU, I'm not sure what chip he has but he said it's supposed to idle at 800 close to it. I've gone through every vacuum line in the engine bay and replaced any that even remotely looked old. I'm fairly positive I put them in the right place since I only took off one line at a time. I took pictures of a few of the Scanmaster readings that I thought were important but if anymore are needed please let me know. The IAC valve was replaced about a year ago, if that helps any. But I would love you guys feedback and help. Thanks!

 

[Caleb W.]

I've read through a lot of the stickys and browsed several days worth of this forum and still no luck

 

[crashedout1]

Reset idle air control and adjust idle screw on throttle body

 

[TurboDave]

Well one way people get their idle up to high is to crank up what they think is the idle screw. This forces the IAC down to zero and it can then no longer control idle. You need to start backing off that screw (air bleed screw) in increments. Each one full turn you'll need to readjust the tps. Keep adjusting each until you get the IAC to read about 20 or so and TPS at .42 to .44


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[crashedout1]

You have to use a volt meter or the scannmaster to adjust i prefer volt meter cause its right there under the hood.

 

[TurboDave]

Volt meter is fine, but I find Scanmaster to be best, especially for IAC. Just set it up on dash an face it forward so it's visible under the open hood.


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[TurboDave]

BTW, make these adjustments on a warmed up engine and at idle.


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[Caleb W.]

Will these adjustments help my cold start issues when done correctly? I have to throttle it out for a few minutes so it doesn't die. I'm assuming they would since the iac will be working as it should. I'm waiting until the rain stops to do these adjustments but I'll for sure let you guys know if it worked.

 

[crashedout1]

Shouldn't have to touch the gas when starting cold

 

[Caleb W.]

Im beginning to think there is a vacuum leak behind the dash. Any tips you guys could give me on that?
I do have to give just a slight bit of throttle when its warmer outside like around 70 degress or up... but when its mid to low 60s I do not.

 

[Caleb W.]

It doesnt help that it keeps randomly flashing code 41

 

[Frederickdav]

After several years of dumping money and sweat and tears[from the sweat getting in my eyes] ,I tried a new chip. What a difference! The 87T runs like it should. I think it has something to do with alcohol in the gas that wasn't there in the eighties.

 

[Caleb W.]

What chip did you put in? I'll mention it to my step dad and see what he thinks.

 

[Caleb W.]

It has an 87 ECU with a turbo tweak chip. Would swapping in an exact replacement change anything?

 

[FWC]

I know this thread is like 8 years old now, but did you ever figure out the cold idle issue? I'm experiencing the same thing now with my '87 with the TT chip and the only thing that helps is to make it high idle by messing with that adjustment screw

 

['87 Turbo "T"]

I know this thread is like 8 years old now, but did you ever figure out the cold idle issue? I'm experiencing the same thing now with my '87 with the TT chip and the only thing that helps is to make it high idle by messing with that adjustment screw

OP hasn't been on in 6+ years. You should post up your Scanmaster numbers so we have more data to work with.

 

[FWC]

OP hasn't been on in 6+ years. You should post up your Scanmaster numbers so we have more data to work with.

Well, I just adjusted the min air screw until it is able to idle cold, but that means my IAC is 0 at hot idle and it idles high at about 1100 RPM

Should also mention: TT Street chip with a 3" LT MAF and Translator. Oxygen sensor is original, but I doubt that has to do with my issue since it is when it first starts up.

I might start a new thread if I get the IAC to about 10 (hot) and it still won't idle cold.

 

['87 Turbo "T"]

Check for and fix any & all vacuum leaks, make sure you have your Translator settings correct, what's the TPS set at? That affects the IAC, you have to do the dance & set them both. You change one it affects the other.

Check & reset IAC.

IAC Reset Procedure

Turbo Regal Performance Recipes

www.gnttype.org

Change the O2. it's 37+ years old. Try to get the Denso. They quit making them but there are other options available.