ECMlink 98 GST Idle tuning

[Zanaqqq]

Been awhile since I posted on here..

So I’m having some issues getting the car to reach its target idle. The airflowperrev is around .28 to .35 at idle. My wideband will read it’s running lean when it’s near target idle but when I add a little more fuel to get that 14:7 it raises the idle too. I’m wondering what issue this could be and what’s causing it.

It also has a rev hang and sits about 1500 before coming back down to 1100-1200. My target idle is set to 750 on this log I’ve uploaded below.

The one thing I saw was my ISC position was way to high but the airflow read okay.

I’ll take any ideas or things to check.

 

[Zanaqqq]

That ground doesnt matter as you're 2g. 2g doesn't use the idle position switch. Ecu shows throttle closed by TPS.

I’ll remove that ground then. Thanks for that info

 

[DSMPT]

Where is the SAS? I don’t think I’ve ever heard of that before. My biss is bottomed right now.

On 1g thrrotle body, this is the IPS with the fixed SAS. You can see this is locked by a nut and the tip is touching the throttle plate stop. So if this part is tightened in more than it should, which means it pushs the throttle plate open more at TPS 0% position, and the engine would get more air from there and would cause higher idle speed (technically the same as vacuum leak)
I assume you run a 2g TPS, 2g TPS has the IPS so you wouldn't need the 1g IPS but you still need it as the fixed SAS.

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[Zanaqqq]

On 1g thrrotle body, this is the IPS with the fixed SAS. You can see this is locked by a nut and the tip is touching the throttle plate stop. So if this part is tightened in more than it should, which means it pushs the throttle plate open more at TPS 0% position, and the engine would get more air from there and would cause higher idle speed (technically the same as vacuum leak)
I assume you run a 2g TPS, 2g TPS has the IPS so you wouldn't need the 1g IPS but you still need it as the fixed SAS.

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I’ll check that tomorrow, I should just be able to turn it counter clockwise correct?

 

[DSMPT]

I should just be able to turn it counter clockwise correct?

To close the throttle plate, yes. It would decrease the idle engine speed in case if the high idle is caused by excessive air through the throttle plate.
The position is set from factory, so usually no need to touch but once if it has changed the position, you should set it as the factory position as below.

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[Zanaqqq]

To close the throttle plate, yes. It would decrease the idle engine speed in case if the high idle is caused by excessive air through the throttle plate.
The position is set from factory, so usually no need to touch but once if it has changed the position, you should set it as the factory position as below.

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I’ll do that tomorrow, thanks

 

[pauleyman]

I had caps on them before I’ll put back on. I don’t really know where each one is supposed to go

Doesn't matter as long as you dont have a leak.

I’ll remove that ground then. Thanks for that info

This is assuming you have a 2g TPS and idle control is as a 2g is intended. If you ever happen to own a 1g the idle position switch grounds through the throttle body. Factory there is a small bracket that connects to a throttle body bolt. Thats because the gaskets electrically isolate. The IPS is just a simple on off ground switch and the factory ground is on the intake manifold, hence the need for the little bracket. In your case you ran the screw directly to ground, that works too. Moot point but thought the explanation would be helpful.

 

[Zanaqqq]

To close the throttle plate, yes. It would decrease the idle engine speed in case if the high idle is caused by excessive air through the throttle plate.
The position is set from factory, so usually no need to touch but once if it has changed the position, you should set it as the factory position as below.

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I did that this morning and it seemed to make no difference. The car is still idling 1400-1700 once it warms up. While it cold idle it will be around 1000-1200 until it gets to operating temp. My smoke leak detector came today so I’ll test it later assuming I have air getting in somewhere

 

[dwb]

I did that this morning and it seemed to make no difference. The car is still idling 1400-1700 once it warms up. While it cold idle it will be around 1000-1200 until it gets to operating temp. My smoke leak detector came today so I’ll test it later assuming I have air getting in somewhere

Curious if you made any progress? Have you already addressed the FIAV? That thing haunted me for a long time. Either install a bypass plate or you can close the passage if you pull the freeze plug and turn this "adjuster," iirc, clockwise as far as it goes.
Post a new log after you fixed open loop checkbox and one that shows some ISC movement. Maybe a bit longer log with a few blips of the throttle.

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