a/c kills engine on swap
a/c kills engine on swap I have 6.0 swap with a mild cam. This swap is in a 68 C10 pickup. My PCM has no park/drive hookup or a/c input so it does not use those tables. Are there any tricks to get this running seemless? When the a/c kicks on it drops rpms so low it will die sometimes. It did not die with the factory cam in but still dropped really low. It would be nice to have it not drop at all.
Did you simply change cams or did you make calibration changes to account for the new cam? You need a good tuner to make adjustments within the calibration for the AC on vs. off (and possibly the cam). I prefer to have the AC wired through the VCM so it controls the fan, idle and timing when the AC is on or off. Bypassing the VCM for AC is fine, but doesn't allow as much flexibility - but it will still work.
I'm running aftermarket AC (sanden compressor)on a stock 6.0 and 5.3 swap. Both are DBW. The change in rpm is not even noticeable with the compressor cycling.
I would initially check on the AC system first. What compressor are you running?
I would initially check on the AC system first. What compressor are you running?
TECH Resident
Joined: Feb 2014
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From: Encinitas CA
What year is the engine? My 2008 L92 corrects idle speed when the compressor is running. My AC clutch is also configured separate from the PCM.
I wonder if there is a tuning setting to adjust like idle speed?
Or perhaps your IAC idle air controller isn't working properly.
I think there is a base idle setting in the throttle body that could be adjusted, too?
Doug
I wonder if there is a tuning setting to adjust like idle speed?
Or perhaps your IAC idle air controller isn't working properly.
I think there is a base idle setting in the throttle body that could be adjusted, too?
Doug
I do tuning but I cant adjust the A/C tables since I dont know how to wire the factory PCM to control the compressor. From what i understand is the PCM only uses those tables when it controls the a/c compressor. I am using a factory 2001 5.3 truck a/c compressor with original PCM. It also dipped down quite a lot even with the stock cam setup. The cam has a bit of a lope to it which seems to make it easy to die on me when the a/c kicks on.
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TECH Resident
Joined: Feb 2014
Posts: 954
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From: Encinitas CA
Are you sure your compressor isn't locked up? Maybe the load is too high?
Can you spin it over by hand easily when things are warmed up?
It takes me a few ftlbs of torque to turn over my pump by hand when things are warm. When cold it turns over more easily.
Mine is a standalone setup. The PCM just adjusts idle speed when the clutch compressor is locked. My PCM doesn't control the clutch. My Vintage Air panel / thermostat calls for cooking and therefore clutch lockup. I have the AC pressure switch inline between the AC control panel and compressor clutch.
Doug
Can you spin it over by hand easily when things are warmed up?
It takes me a few ftlbs of torque to turn over my pump by hand when things are warm. When cold it turns over more easily.
Mine is a standalone setup. The PCM just adjusts idle speed when the clutch compressor is locked. My PCM doesn't control the clutch. My Vintage Air panel / thermostat calls for cooking and therefore clutch lockup. I have the AC pressure switch inline between the AC control panel and compressor clutch.
Doug
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Verdad Gallardo TECH Resident
Joined: Feb 2014
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From: Encinitas CA
Isn't there a base idle setting in the throttle body - a mechanical port that allows you to set base idle before the IAC?
I think there is.
Perhaps the IAC can't keep up with engine airflow demand once the compressor load is on the system? Could you try setting up the base idle without the IAC?
Take a look at manifold pressures. If you are seeing temps around 40 degrees or less at the outlet, it probably isn't too overcharged.
Doug
I think there is.
Perhaps the IAC can't keep up with engine airflow demand once the compressor load is on the system? Could you try setting up the base idle without the IAC?
Take a look at manifold pressures. If you are seeing temps around 40 degrees or less at the outlet, it probably isn't too overcharged.
Doug
Is this a hybrid AC system. The LQ4 compressor with an older car AC system?
If so what are you using for the compressor switch? Trinary, the 2 switch system used on trucks? Are you using an up to date expansion valve? What are your hi/low AC pressures?
If so what are you using for the compressor switch? Trinary, the 2 switch system used on trucks? Are you using an up to date expansion valve? What are your hi/low AC pressures?