Engine stalls when a/c turned on
01-24-2013, 02:14 PM
#1
Staging Lane
Thread Starter
iTrader: (1)
Join Date: Nov 2004
Location: Laredo, Texas
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
Engine stalls when a/c turned on In the final stages of a 1971 Chevelle LS3 setup. My problem is that the engine stalls when the a/c is turned on. It seems as if the PCM doesn't compensate for the load. The a/c is running independantly, not being controlled by the pcm. Is that my problem? Or should the PCM be able to adjust for the load regardless? Any help would be greatly appreciated. Here's a few pics of the project car.
01-24-2013, 04:58 PM
#2
9 Second Club
iTrader: (2)
Join Date: Jul 2002
Location: on the dyno tuning in MD
Posts: 2,583
Likes: 0
Received 1 Like
on
1 Post
That is one sweet Chevelle!! Yes, if your A/C is not seen by the PCM, it won't compensate for it. There should be a way to connect into the needed pin on the PCM and tell it when the A/C is on - it will probably take some research to figure out how to wire it, but it should be doable...
01-30-2013, 07:31 PM
#3
On my mustang i had the same problem. My PCM had AC input and it still stalled unless i lightly raised the idle with the throttle for a second or two then it was fine. Also if i started it with the ac already on with would usually surge or stall.
I would definately wire the PCM to sense the AC being on and play with the tune.
I would definately wire the PCM to sense the AC being on and play with the tune.
01-30-2013, 07:41 PM
#4
TECH Enthusiast
iTrader: (17)
Join Date: Sep 2007
Location: Southern NJ
Posts: 634
Likes: 0
Received 0 Likes
on
0 Posts
It may not apply but hoe old is your battery and alternator.
When my battery started to fail my engine would die when I turned on my A/C. Seems the A/C pulled so much power there wasn't enough to run the engine.
Just a thought.
When my battery started to fail my engine would die when I turned on my A/C. Seems the A/C pulled so much power there wasn't enough to run the engine.
Just a thought.
01-30-2013, 10:07 PM
#5
TECH Apprentice
iTrader: (3)
Join Date: Jan 2008
Location: San Diego
Posts: 394
Likes: 0
Received 0 Likes
on
0 Posts
yes, you need to tell the PCM the AC is on and it should bump idle 50 rpm (at least my LS1 does) just need to figure out which wire, AC request, signal or whatever. I got it all hooked up with mine and Vintage Air setup.
01-31-2013, 08:32 AM
#7
TECH Apprentice
iTrader: (3)
Join Date: Jan 2008
Location: San Diego
Posts: 394
Likes: 0
Received 0 Likes
on
0 Posts
Here is a post a while back I did on wiring up my VA to PCM #16 post has a pdfhttps://ls1tech.com/forums/conversio...m-drawing.html
what AC are you using?
Trending Topics
01-31-2013, 09:23 AM
#8
It is probably something in the tune that just needs adjusted. Maybe more minimum airflow on the lower rpms than idle settings. So if it gets a small pull down on rpm, the airflow will be added to make it stay back up.
One or two tables should fix it.
Remember, old cars that had carburetors? They didn't die when you turned on ac.... It is just a tweak to an adder table that is needed. The cam you are using requires a bit of changes.
One or two tables should fix it.
Remember, old cars that had carburetors? They didn't die when you turned on ac.... It is just a tweak to an adder table that is needed. The cam you are using requires a bit of changes.
02-01-2013, 02:36 PM
#9
Staging Lane
Thread Starter
iTrader: (1)
Join Date: Nov 2004
Location: Laredo, Texas
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
ssduane, that is a great diagram. I printed it, but I might be having to go a different route. I found a good deal on a GMPP engine control setup, but I am running into the same wall. I just posted another thread, trying to figure out if that setup can handle a/c request.
