GVR-4 ECMLink ISC live data

[Elpizer2]

I am running maft+ 3 inch gm maf ecmlink, the thing is that I'm trying to tune the idle but I don't see the ISC live data, also can't add

ISC position
Learn idle value

Why?

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[Justin DuBois]

Those are "Displayed" values. You can only access the ones that have been captured to log.
What you need to do is connect to the ECU live - and edit "Captured" values (F10).

 

[Elpizer2]

Those are "Displayed" values. You can only access the ones that have been captured to log.
What you need to do is connect to the ECU live - and edit "Captured" values (F10).

Ok this is my problem
I can't low the ISC position value by rotating the screw. And when I turn on the a/C the ISC position number goes up, like closing. The idle does not goes up. Why?

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[Justin DuBois]

By screw, are you referring to the BISS on the throttle body?
Adjusting the BISS to center the ISC only works when the engine is running and the coolant temp is in the normal operating range, and the ECU is in closed loop mode. Look for the idle switch. The switch (or a simulation of the switch in ECM Link settings) is needed for idle control.

If you are up to temp, and the BISS has no impact on the idle speed, then maybe your BISS is clogged?

ISC - 0 = closed
The ISC will open more when you turn on the AC to allow more air to compensate for the additional load created by the AC compressor.

 

[Elpizer2]

By screw, are you referring to the BISS on the throttle body?
Adjusting the BISS to center the ISC only works when the engine is running and the coolant temp is in the normal operating range, and the ECU is in closed loop mode. Look for the throttle close position switch. The switch (or a simulation of the switch in ECM Link settings) is needed for idle control.

If you are up to temp, and the BISS has no impact on the idle speed, then maybe your BISS is clogged?

ISC - 0 = closed
The ISC will open more when you turn on the AC to allow more air to compensate for the additional load created by the AC compressor.

YEs I loose the BISS screw and it idles up, if tight it idle downs but the ISC position does not move in live data. Also then I return the A/C on, idle is down, it doesn't compensate it. Why?

 

[Justin DuBois]

YEs I loose the BISS screw and it idles up, if tight it idle downs but the ISC position does not move in live data. Also then I return the A/C on, idle is down, it doesn't compensate it. Why?

Check the throttle close position switch function. If that is working, you may have a bad or sticky ISC. You can check the ISC coil resistance with a multi meter. You may need to remove it, and clean it.

 

[Elpizer2]

Check the throttle close position switch function. If that is working, you may have a bad or sticky ISC. You can check the ISC coil resistance with a multi meter. You may need to remove it, and clean it.

The ISC coils resistence is good like 30 ohms and it's clean, but still doesn't move or work, I tried and old metal oem one and a black one from amazon, this one

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[Justin DuBois]

The ISC coils resistence is good like 30 ohms and it's clean, but still doesn't move or work, I tried and old metal oem one and a black one from amazon, this one

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Hmm - If the step number changes but no movement in the ISC, then its time to check the wiring to the ECU, and the Voltage from the ECU.

And the throttle close position switch? does that change in the ecm link live data?

 

[Elpizer2]

And the throttle close position switch? does that change in the ecm link live data?

The idle position switch is working, however I'm emulating it with ecmlink tool from 0% to 100%

My wiring is

• ISC Pin 1 - Blue - Goes to pin 58 at ECU
• 12v Pin 2 - Red
• ISC Pin 3 - Yellow - Goes to pin 59 at ECU
• ISC Pin 4 - Black - Goes to pin 68 at ECU
• 12v Pin 5 - Red
• ISC Pin 6 - White -Goes to pin 67 at ECU

And the throttle close position switch? does that change in the ecm link live data?

The idle switch is connected and working I tested it using a multimeter, non continuity once throttle moves. But when I log live data, idle switch stays in 0. No changes. So Simulate the idle position switch on ecmlink to get 0% TPS to 100%

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[Elpizer2]

Hmm - If the step number changes but no movement in the ISC, then its time to check the wiring to the ECU, and the Voltage from the ECU.

And the throttle close position switch? does that change in the ecm link live data?

Opened the ISC and the OEM 1g one they look good

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[danl]

When you go from me in off position to key in run does the isc motor turn smoothly?

The ecu isc drivers are commonly damaged on these cars.

 

[Elpizer2]

When you go from me in off position to key in run does the isc motor turn smoothly?

The ecu isc drivers are commonly damaged on these cars.

No it doesn't sound.

the ecu looks good as well. What are the ISC drivers?

 

[steve]

The idle switch and idle switch pin (actual input) show as 0 in all the pictures you posted, at least one or two look like the throttle should be closed so it doesn't look like your IPS is working or you are missing the ground strap to the TB or the ground strap from the intake to the firewall or all three.

I'd also like to see the TPSVolts to know that the TPS is adjusted correctly.

Until the ECU sees the IPS close it's not going to try and manage the idle speed.

 

[Justin DuBois]

No it doesn't sound.

the ecu looks good as well. What are the ISC drivers?

The drivers are on the ECU board. If you can resolve the idle switch issue, you should see a change to the ISC stepper number. If the number is changing but the ISC is not, thats when you should suspect the ISC drivers on the ECU board. Do you know the health of the ECU? Lots of funny things happen when the leaking capacitors on the boards etch the traces, causing various functions to fail. At some point if you have resolved the grounding issues to the TB, and the TPS and close switch are working, you may want to have the ECU inspected and repaired if necessary.

 

[Elpizer2]

The idle switch and idle switch pin (actual input) show as 0 in all the pictures you posted, at least one or two look like the throttle should be closed so it doesn't look like your IPS is working or you are missing the ground strap to the TB or the ground strap from the intake to the firewall or all three.

I'd also like to see the TPSVolts to know that the TPS is adjusted correctly.

Until the ECU sees the IPS close it's not going to try and manage the idle speed.

Ok Could you tell me where these Throttle Body, intake manifold and engine grounds goes ? I'm trying to verify that I am not missing them first.

I am trying to see where all the engine grounds are just to test them, I have N/T Throttle Body, so trying to see front the firewall to the engine, how they should be installed .

 

[Elpizer2]

Ok I see these grounds, tested them and reclean them from any rust but still doesn't work. The idle position switch sends ground once throttle closed. So I suppose is the ECU. I'm in other country. Could you send me like a picture about what driver do I need to replace? So I can see please thanks

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[steve]

I don't think I have a picture of the TB Ground strap for a NA TB but here's the one on a 91-94 Turbo TB.
Your last two pictures show the manifold ground cable.

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The Solenoid driver ICs on the ECU are IC105 and IC107. The other ICs are to control relays and solenoids.
Because it's common for capacitor leakage to damage the ECU PCB traces for the ISC I'd check from the IC pin to the ECU connector for continuity before replacing the IC.

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Here's the datasheet for the Driver.

 

[Elpizer2]

I don't think I have a picture of the TB Ground strap for a NA TB but here's the one on a 91-94 Turbo TB.
Your last two pictures show the manifold ground cable.

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The Solenoid driver ICs on the ECU are IC105 and IC107. The other ICs are to control relays and solenoids.
Because it's common for capacitor leakage to damage the ECU PCB traces for the ISC I'd check from the IC pin to the ECU connector for continuity before replacing the IC.

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Here's the datasheet for the Driver.

I have a N/T throttle body which uses a ground cable from firewall to a throttle body bolt that screws in the intake manifold. I have continuity from idle position switched to the ECU plug. So I thinking I'll need to find that driver and try. Car starts and run but low idle 660-700 cold until warms up to 1100 rpm hot

 

[pauleyman]

I don't think I have a picture of the TB Ground strap for a NA TB but here's the one on a 91-94 Turbo TB.

Does the nt throttle body have one? The throttle body should ground to intake through the mount bolts. That's not true on a turbo because there is a throttle body elbow so there is an additional elbow with gasket and the bolt heads dont touch the throttle body as they do on NT.

Your last two pictures show the manifold ground cable.

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The Solenoid driver ICs on the ECU are IC105 and IC107. The other ICs are to control relays and solenoids.
Because it's common for capacitor leakage to damage the ECU PCB traces for the ISC I'd check from the IC pin to the ECU connector for continuity before replacing the IC.

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Here's the datasheet for the Driver.

 

[steve]

Does ECMLink see the IPS working now? If not you have to fix that first.

Does the nt throttle body have one? The throttle body should ground to intake through the mount bolts. That's not true on a turbo because there is a throttle body elbow so there is an additional elbow with gasket and the bolt heads dont touch the throttle body as they do on NT.

Don't know? It's has a place for the screw but like you say the bolt and studs for the manifold should make direct contact with the TB flange and provide the ground.

 

[Justin DuBois]

If you open the ECU and take a good quality image of the board, someone with experience inspecting the ECU board components may chime in.

I sent my ECU to ECM Tuning. Worth the bench fee.

 

[Elpizer2]

If you open the ECU and take a good quality image of the board, someone with experience inspecting the ECU board components may chime in.

I sent my ECU to ECM Tuning. Worth the bench fee.

I have continuity from idle position plug to pin 14 ECU

ECU pictures attached

It's JE33IA934D code on board

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[steve]

That's a 1990 ECU 4478 = E2T34478 = MD145903 1990 Federal MT Turbo AWD ECU.

Since your car is a 93 you shouldn't have had to swap any ISC pins (I don't think but it's been a long time) but you do need to swap pin 6 and 14 in the ECU connector. Have you done that? Pin 6 should have the green wire from the IPS and pin 14 the green/white wire from the MAF (MAF Reset). Based on what you just wrote they haven't been swapped and need to be.

I only remember having to change the ISC pins when you put a 91+ ISC into a 90 car and you were making adapter. I don't ever remember needing to do so when I put a 90 ECU in a 91+ car or a 91+ ECU in a 90 car but my brain is fried from struggling putting the door car back on the wife's TT.

 

[Elpizer2]

That's a 1990 ECU 4478 = E2T34478 = MD145903 1990 Federal MT Turbo AWD ECU.

Since your car is a 93 you shouldn't have had to swap any ISC pins (I don't think but it's been a long time) but you do need to swap pin 6 and 14 in the ECU connector. Have you done that? Pin 6 should have the green wire from the IPS and pin 14 the green/white wire from the MAF (MAF Reset). Based on what you just wrote they haven't been swapped and need to be.

I only remember having to change the ISC pins when you put a 91+ ISC into a 90 car and you were making adapter. I don't ever remember needing to do so when I put a 90 ECU in a 91+ car or a 91+ ECU in a 90 car but my brain is fried from struggling putting the door car back on the wife's TT.

I have a 91 + ISC valve, it's a N/T 91+ Throttle body.

What pins on the ISC valve do I need to swap? Can I swap them on the ECU connector instead?

I'll swap Pin 6 and 14 on the ECU connector and let you know soon

 

[steve]

I don't believe you have to swap any ISC pins. That's what I said above. You do need to swap ECU pins 6 and 14 since you're putting a 90 ECU into the 91+ vehicle.

There's how to quickly swap the pins at the ECU connector on a 1G connector.

How to remove/replace pins in harness connectors

Disclaimer: I am not responsible for anything done to your car/equipment. Use this information at your own risk. It is possible to damage components if you don't know what you are doing and don't use common sense. Keep in mind do these things at your own risk!That being said, lets get onto the...

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