Faking a/c to raise idle speed - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Dustytrix · 09-27-2019, 09:01 PM

I have a 6.0 gen3 FI swap in 67c10. My air is vintage sure fit. All my air is controlled by vintage controls. My fans are controlled by engine temp/ecm. The engine wants to stumble at red lights or stopping when ac is being used. I talked to my tuner and he said ecm is tuned for ac idle adjustment. OK I want to send a signal to ecm to get it to raise idle when ac is on? I sent 12volts to red 17 and grounded red 55 but nothing changes. Does anyone have any ideas? What I can do to fake ecm inputs?

87chevy.com · 09-28-2019, 11:43 PM

Lol why fake it when you can simply have the ECU do it? If you had a gen4 or gen5 peobably be another story, you have a simple solution.

Dustytrix · 10-06-2019, 08:21 PM

Quote:

Originally Posted by 87chevy.com

Lol why fake it when you can simply have the ECU do it? If you had a gen4 or gen5 peobably be another story, you have a simple solution.

OK thanks for reading the question, it states that I want the ecm to do it. But I don't have the info for the how part.

GIZZ · 10-06-2019, 10:16 PM

Have your tuner look at it again, if it's all hooked up it's in the tune.

87chevy.com · 10-07-2019, 11:28 PM

Quote:

Originally Posted by Dustytrix

OK thanks for reading the question, it states that I want the ecm to do it. But I don't have the info for the how part.

Sorry, I thought I read it correct and your post ended on how to fake ecu inputs
If you simply pull a 2002 Camaro ac schematic that's the end of the thread.

ls1nova71 · 10-08-2019, 05:11 AM

What year is your PCM and harness? It makes a difference. 99-02 trucks use pressure switches and 2003 and up trucks use a pressure sensor. 98-02 Camaro also use a pressure sensor.

87chevy.com · 10-09-2019, 12:07 AM

Quote:

Originally Posted by ls1nova71

What year is your PCM and harness? It makes a difference. 99-02 trucks use pressure switches and 2003 and up trucks use a pressure sensor. 98-02 Camaro also use a pressure sensor.

Yep, true.. if you are using a mechanical fan use truck setup, would work fine, if using electric fan, use Camaro schematic and have it tuned accordingly

**First c10** · 10-09-2019, 12:58 PM

I adjusted my idle when in gear and set the TC lock/unlock RPMs I adjusted them when the truck was at a speed below like 5 mph(in the Tune). took care of the stumble when the AC was on coming to a stop sign. I have a 2011 gen IV so I could not tell the ECM the AC was on for it to adjust.

09-27-2019, 09:01 PM	#1
Dustytrix Registered User Join Date: Jan 2012 Location: Petal,Ms. Posts: 428	Faking a/c to raise idle speed I have a 6.0 gen3 FI swap in 67c10. My air is vintage sure fit. All my air is controlled by vintage controls. My fans are controlled by engine temp/ecm. The engine wants to stumble at red lights or stopping when ac is being used. I talked to my tuner and he said ecm is tuned for ac idle adjustment. OK I want to send a signal to ecm to get it to raise idle when ac is on? I sent 12volts to red 17 and grounded red 55 but nothing changes. Does anyone have any ideas? What I can do to fake ecm inputs?

09-28-2019, 11:43 PM	#2
87chevy.com BMW & ASE Master Certified Join Date: Feb 2004 Location: Houston, Texas Posts: 1,266	Re: Faking a/c to raise idle speed Lol why fake it when you can simply have the ECU do it? If you had a gen4 or gen5 peobably be another story, you have a simple solution. __________________ 1987 Silverado - L83 5.3 w/ 6L80e ,A/C,P/W,P/L,TILT, HID projectors, Wilwood C-10 Pro Spindles w/ 2018 silverado front brakes & C-5 Corvette Rear Disc Brakes 1999 BMW 528i - 5.7 LS1 w/ 4l60e, Ford 8.8 IRS w31 spline posi & FX-r projector retrofit New project: 2006 BMW x5 6cyl AWD to L83 6l80e 4wd to 2WD / RWD A poor man buy's it twice finally got my domain name back, 87chevy.com.... site rework in progress

10-06-2019, 10:16 PM	#4
GIZZ Registered User Join Date: Jun 2005 Location: Vancouver Posts: 111	Re: Faking a/c to raise idle speed Have your tuner look at it again, if it's all hooked up it's in the tune. __________________ GIZZmotorsports on YouTube & my panel truck build '69 c10 panel, '75 c35 flatdeck car hauler

10-08-2019, 05:11 AM	#6
ls1nova71 Registered User Join Date: Dec 2009 Location: Independence Mo Posts: 4,119	Re: Faking a/c to raise idle speed What year is your PCM and harness? It makes a difference. 99-02 trucks use pressure switches and 2003 and up trucks use a pressure sensor. 98-02 Camaro also use a pressure sensor. __________________ My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html

10-09-2019, 12:58 PM	#8
First c10 Registered User Join Date: Dec 2012 Location: Los Banos CA Posts: 2,706	Re: Faking a/c to raise idle speed I adjusted my idle when in gear and set the TC lock/unlock RPMs I adjusted them when the truck was at a speed below like 5 mph(in the Tune). took care of the stumble when the AC was on coming to a stop sign. I have a 2011 gen IV so I could not tell the ECM the AC was on for it to adjust. __________________ 1956 Chevy Bel Air 2 door 1956 Chevy 210 4 Door 1970 K20 LWB project the Hulk build w/Supercharged 4.8L-ly2/4L60E HULK BUILD 1970 C10 Yellow/White Deluxe LWB w/ 5.3L-LC9/6L80E 1968 K10 LWB Dark green my son calls it "THE HULK Jr"HULK JR SOLD GO GO!!!



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