Replacing the GMPP ECU with a Production E67 for a/c Control.

I have an FJ80 that I put a GMPP 6.0 with a 4L80 into. At the time of install I did not realize that the A/C request was not just an input into the ECU. It seams that this is much more complex in terms of a/c request and output to compressor relay. I installed a pressure switch and the RPM Extreme a/c request module only to find out that the GMPP does not support a/c control at all. So the question is, is there a factory calibration to use with a production E67 ECU that would be a direct drop in to work with the GMPP harness and supporting parts. Being that the MAF and the ACC Pedal are what would typically be found on a truck engine I'm not sure what base calibration will work with this GMPP set up. The issue that I am wanting to fix is the drop in idle and occasional stalling when the a/c compressor cycles. Thanks in advance.

late Trailblazer SS's were E67's. They have a hard wired cruise control too. I've never tried it.

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Originally Posted by Alvin

late Trailblazer SS's were E67's. They have a hard wired cruise control too. I've never tried it.

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So it's been 4 years since this install, I searched through my emails and found a reply to my GMPP parts rep. I forgot that we had discussed this and I actually have a Trailblazer SS ECU here that I ordered back then. I think that wiring wise that was the closest match. The issue from what I remember is that the Trailblazer SS does not have VVT and the 6.0 that I have does. Does anyone know if this is something that can be activated with HP Tuners? I would guess that it's more common to disable this feature then activate it.

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Originally Posted by TunedIn

So it's been 4 years since this install, I searched through my emails and found a reply to my GMPP parts rep. I forgot that we had discussed this and I actually have a Trailblazer SS ECU here that I ordered back then. I think that wiring wise that was the closest match. The issue from what I remember is that the Trailblazer SS does not have VVT and the 6.0 that I have does. Does anyone know if this is something that can be activated with HP Tuners? I would guess that it's more common to disable this feature then activate it.

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So I don't KNOW the answer, but I took a few minutes to poke around.

The TBSS tunes in the repository do have the Variable Camshaft tables in Engine -> Airflow -> Variable Camshaft.

I also found a pinout that shows the CMP controls exist on X2:14 and X2:15 (Intake) and X2:50 and X251 (Exhaust):

14 PK/BK 6395 Camshaft Position (CMP) Actuator Solenoid -- Intake Bank 1 Control
15 TN/BK 6397 Camshaft Position (CMP) Actuator Solenoid -- Intake Bank 2 Control

50 WH/BK 6396 Camshaft Position (CMP) Actuator Solenoid -- Exhaust Bank 1 Control
51 GY/BK 6394 Camshaft Position (CMP) Actuator Solenoid -- Exhaust Bank 2 Control

So from my point of view there is a good possibility it'll do the job.. but I can't say that with any certainty. It could be that the tables exist but aren't enabled for every OS.

Alvin would know. He has more TBSS experience than anyone active on the board.

Get rid of the VVT would be my recommendation.. No one trying to make serous power with a GEN 4 uses it.. It just adds complication. They rarely have good VVT control if the thing spins a decent amount of RPM. not worth it.

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Originally Posted by TunedIn

I have an FJ80 that I put a GMPP 6.0 with a 4L80 into. At the time of install I did not realize that the A/C request was not just an input into the ECU. It seams that this is much more complex in terms of a/c request and output to compressor relay. I installed a pressure switch and the RPM Extreme a/c request module only to find out that the GMPP does not support a/c control at all. So the question is, is there a factory calibration to use with a production E67 ECU that would be a direct drop in to work with the GMPP harness and supporting parts. Being that the MAF and the ACC Pedal are what would typically be found on a truck engine I'm not sure what base calibration will work with this GMPP set up. The issue that I am wanting to fix is the drop in idle and occasional stalling when the a/c compressor cycles. Thanks in advance.

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Discrete AC request can be enabled in any E67. I can do it.

P.S. Can you post stock GMPP 6.0 calibration?