1984 Buick GN Turbo Upgrade, 3k idle

[Gn.Cal]

Hello all, I am new to this forum and glad to be a part of the Turbo Buick group. This being said I’ve always wanted a Grand national and finally got myself a 84 Buick hot air GN. It has originally 64k miles. It sat with the previous 1st owner for 20 years. Once I took owner ship I decided to replace stock parts Water pump, gaskets, spark plugs etc. Ran great, then decided to get some more power behind the wheels.

That being said, now I can’t figure out what’s going on with the car.

What’s new

1. 84/85 Turbo stage 1 upgrade from work turbo.
2. Upgraded stainless steel headers
3. Upgraded down pipe from G body.com
4. Upgraded exhaust from pypes.
5. Upgrade LS1 maf
6. 86/87 ICCM with coil
7. 86/87 computer
8. Turbo tweak chip
9. Scan master 2.0

This is all that was upgraded/updated.

The car starts off with an extreme high idle at 3k and can’t find out why. I also tried the smoke machine to see if any air leaks and seems all is sealed up.

Im really stuck and wanting to give up.

Thanks for all your guys support and help. Much appreciated

(Sorry typing this on my phone)

 

[HotAirWH1]

What are your TPS & IAC numbers at idle ? Your TPS should be 0.40-0.46 volts & IAC between 10 -20 when the engine is warm and idling.

I use Turbobuick.com thread by - Ken Mosher

Read this thread > Setting idle screw on TB

Inspect your throttle body and linkage for mechanical operation. (nothing sticking)

 

[Chuck Leeper]

Suggest adding #10 to the list: Powerlogger.
Adds a lot of diagnostic capabilities such as data logs to review, etc.

 

[BEATAV8]

The ECU might not know that it's time to idle if the TPS reading is too high, or the IAC might be bad and it's stuck. Or there's a large vacuum leak.
What are the scanmaster readings?

 

[Gn.Cal]

The ECU might not know that it's time to idle if the TPS reading is too high, or the IAC might be bad and it's stuck. Or there's a large vacuum leak.
What are the scanmaster readings?

That’s what I assumed and did a leak test and everything seemed well, but I could be wrong still.

The scanmaster is reading -

AF32
L8 50
INT 128
BL 128
ATS 71
RPM 3300
TPS .48
IAC - (starts at 38 then drops to 0)
CC 159
NAL 00
BB4 00

 

['87 Turbo "T"]

That’s what I assumed and did a leak test and everything seemed well, but I could be wrong still.

The scanmaster is reading -

AF32
L8 50
INT 128
BL 128
ATS 71
RPM 3300
TPS .48
IAC - (starts at 38 then drops to 0)
CC 159
NAL 00
BB4 00

Your AF(should be between 3 & 7) & L8 numbers are WAY out of range from what I'm used to seeing.

I see no CLT-Coolant temp numbers or BAT. BAT wouldn't affect idle speed.

TPS is high, I like .42-.44 at idle.

The fact that the IAC drops to 0 is odd to me. Have you rest IAC? Do you know if IAC is good?

Never seen BB4. May be the 2.0 version though.

Do you have a MAF translator & if so, what are the settings at?

Did you have Eric update the chip when you made your upgrades?

 

[Gn.Cal]

Your AF(should be between 3 & 7) & L8 numbers are WAY out of range from what I'm used to seeing.

I see no CLT-Coolant temp numbers or BAT. BAT wouldn't affect idle speed.

TPS is high, I like .42-.44 at idle.

The fact that the IAC drops to 0 is odd to me. Have you rest IAC? Do you know if IAC is good?

Never seen BB4. May be the 2.0 version though.

Do you have a MAF translator & if so, what are the settings at?

Did you have Eric update the chip when you made your upgrades?

How do I bring down the AF and adjust the L8?

The CLT and Bat I didn’t add since I assumed it wouldn’t be useful.

I reset the IAC but can’t confirm if it’s good, I’ll replace it with a new one.

The TPS is now at .42 at idle.

Yes I have a Maf translator. I will try and get the setting.

The second chip? Sorry, still learning these cars. I just ordered the turbo tweak chip, and used the old chip from the other ECM.

 

['87 Turbo "T"]

How do I bring down the AF and adjust the L8?

The CLT and Bat I didn’t add since I assumed it wouldn’t be useful.

I reset the IAC but can’t confirm if it’s good, I’ll replace it with a new one.

The TPS is now at .42 at idle.

Yes I have a Maf translator. I will try and get the setting.

The second chip? Sorry, still learning these cars. I just ordered the turbo tweak chip, and used the old chip from the other ECM.

You need to have your translator set up with the DIP switches correct & set up for the MAF you have. It should be on the lid, if it isn't here ya go.

https://www.turbotweaksupport.com/files/translatorinstructions.pdf

No second chip. Your Turbotweak chip. Was it reburned from the original set-up? You've made turbo changes, MAF changes. Did you tell Eric the changes or was the chip set-up for your current set-up?

 

[Gn.Cal]

You need to have your translator set up with the DIP switches correct & set up for the MAF you have. It should be on the lid, if it isn't here ya go.

https://www.turbotweaksupport.com/files/translatorinstructions.pdf

No second chip. Your Turbotweak chip. Was it reburned from the original set-up? You've made turbo changes, MAF changes. Did you tell Eric the changes or was the chip set-up for your current set-up?

Yes, I ordered everything from his website, which was the chip, the Maf translator and Maf, and scan master.

He burned the chip to the new changes before it was all ordered.

 

['87 Turbo "T"]

Yes, I ordered everything from his website, which was the chip, the Maf translator and Maf, and scan master.

He burned the chip to the new changes before it was all ordered.

Roger that. Well I'd for sure check your translator settings, check the IAC to verify, & double check for vacuum leaks.

Here's a good tip for the IAC:

IAC Reset Procedure

Turbo Regal Performance Recipes

gnttype.org

 

[Gn.Cal]

Roger that. Well I'd for sure check your translator settings, check the IAC to verify, & double check for vacuum leaks.

Here's a good tip for the IAC:

IAC Reset Procedure

Turbo Regal Performance Recipes

gnttype.org

I’ll review the settings in a bit.

I reset the IAC, did the crossover on the ALD and I can hear the IAC retracting, and give it about a minute and then I disconnected the IAC and start the car. No rough idle, just jumps to 3k rpm.

 

['87 Turbo "T"]

I’ll review the settings in a bit.

I reset the IAC, did the crossover on the ALD and I can hear the IAC retracting, and give it about a minute and then I disconnected the IAC and start the car. No rough idle, just jumps to 3k rpm.

I'd also check & make sure that nothing is stuck as well. Throttle linkage etc.

 

[BEATAV8]

The IAC command going from 38 to zero is good. The computer sees that the RPM is high and it’s commanding the IAC closed to try and reduce the RPM.

So either the IAC did not move
Or the throttle blade is too far open

Try closing the throttle blade? There’s an adjustment screw. Try this first.

 

[pacecarta]

^^

this back the idle screw out to close the throttle blade , its open too much as the iac at zero shows its trying to limit air into motor and has bottomed out.
with the iac at "0" it cant control the idle rpm anymore , closing the throttle blade will lessen the air to the motor and at some point the iac will begin to climb above zero , keep adjusting throttle screw until iac reads 20-30 at operating temp. and recheck in drive . adjusting throttle closed causes tps to drop if it goes below .40 then you should loosen the tps screws and move it to get tps back to .44 , keep turning out the screw untill you get the idle right

 

[pacecarta]

fyi heres a link to explain the scanmaster readings

Scantool Readings

 

[Gn.Cal]

^^

this back the idle screw out to close the throttle blade , its open too much as the iac at zero shows its trying to limit air into motor and has bottomed out.
with the iac at "0" it cant control the idle rpm anymore , closing the throttle blade will lessen the air to the motor and at some point the iac will begin to climb above zero , keep adjusting throttle screw until iac reads 20-30 at operating temp. and recheck in drive . adjusting throttle closed causes tps to drop if it goes below .40 then you should loosen the tps screws and move it to get tps back to .44 , keep turning out the screw untill you get the idle right

I tried adjusting the TB screw and nothing changed which I assumed was weird. I ended up removing the TB and noticed the linkage plate was bent for some reason and straighted it out and now the car is running normal! I genuinely appreciate all the help! I was stuck for 2 months.

 

[Hot Air Beast]

Hello all, I am new to this forum and glad to be a part of the Turbo Buick group. This being said I’ve always wanted a Grand national and finally got myself a 84 Buick hot air GN. It has originally 64k miles. It sat with the previous 1st owner for 20 years. Once I took owner ship I decided to replace stock parts Water pump, gaskets, spark plugs etc. Ran great, then decided to get some more power behind the wheels.

That being said, now I can’t figure out what’s going on with the car.

What’s new

1. 84/85 Turbo stage 1 upgrade from work turbo.
2. Upgraded stainless steel headers
3. Upgraded down pipe from G body.com
4. Upgraded exhaust from pypes.
5. Upgrade LS1 maf
6. 86/87 ICCM with coil
7. 86/87 computer
8. Turbo tweak chip
9. Scan master 2.0

This is all that was upgraded/updated.

The car starts off with an extreme high idle at 3k and can’t find out why. I also tried the smoke machine to see if any air leaks and seems all is sealed up.

Im really stuck and wanting to give up.

Thanks for all your guys support and help. Much appreciated

(Sorry typing this on my phone)

I feel your pain. I bought my 84 GN in Oct 1988 and have bumped into many unusual problems over the last 37 years. All turned out OK with the help of owners on many forums and facebook pages and good luck in finding folks willing and able to work on the car. Think about sharing info on your ride with The Registry and check out my Facebook pages. Send a hello email to phil@zynetonline.com and I will reply with what the Registry is all about and a pdf of the last bi-monthly update I released.
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[HotAirWH1]

Hello all, I am new to this forum and glad to be a part of the Turbo Buick group. This being said I’ve always wanted a Grand national and finally got myself a 84 Buick hot air GN. It has originally 64k miles. It sat with the previous 1st owner for 20 years. Once I took owner ship I decided to replace stock parts Water pump, gaskets, spark plugs etc. Ran great, then decided to get some more power behind the wheels.

That being said, now I can’t figure out what’s going on with the car.

What’s new

1. 84/85 Turbo stage 1 upgrade from work turbo.
2. Upgraded stainless steel headers
3. Upgraded down pipe from G body.com
4. Upgraded exhaust from pypes.
5. Upgrade LS1 maf
6. 86/87 ICCM with coil
7. 86/87 computer
8. Turbo tweak chip
9. Scan master 2.0

This is all that was upgraded/updated.

The car starts off with an extreme high idle at 3k and can’t find out why. I also tried the smoke machine to see if any air leaks and seems all is sealed up.

Im really stuck and wanting to give up.

Thanks for all your guys support and help. Much appreciated

(Sorry typing this on my phone)

Suggestion - you should add your mods to your signature so others will know what they are dealing with when trying to give advice - HAPP NEW YEAR