Ford Mustang Forum banner
Cancel

Please help! Engine stall...

1252 Views 6 Replies 3 Participants Last post by  sic 89 GT, 
sic 89 GT
I have a 1989 GT mostly stock 5speed I've put an electric fan on the car because of over heating issues, the car was working great but in the last few months it's starting to stall out and die on my when I'm coming to a stop... (Only when the ac is on) when coming to a stop if I do not let the rpms come down slowly the car will just drop all the way down and die... Fires right back up and idles fine like nothing happened. I did so e reaserch and found that the alternator could he at fault as it was the stock alt. and can't handle the extra load so I put a 130amp alt w/upgraded 4g power wire and still same issue... I'm pulling my hair out!! I live in Las Vegas and it's HOT my girl and kid will not ride in the car if there is no a/c, please any info would much appreciated
Save Share
1 - 7 of 7 Posts
SPeace-ATL
sic 89 GT said:
I have a 1989 GT mostly stock 5speed I've put an electric fan on the car because of over heating issues, the car was working great but in the last few months it's starting to stall out and die on my when I'm coming to a stop... (Only when the ac is on) when coming to a stop if I do not let the rpms come down slowly the car will just drop all the way down and die... Fires right back up and idles fine like nothing happened. I did so e reaserch and found that the alternator could he at fault as it was the stock alt. and can't handle the extra load so I put a 130amp alt w/upgraded 4g power wire and still same issue... I'm pulling my hair out!! I live in Las Vegas and it's HOT my girl and kid will not ride in the car if there is no a/c, please any info would much appreciated
Click to expand...
I know this will sound strange, but is your neutral switch on the top cover of your T-5 connected? It shorts when the car is in neutral and is open when the car is in gear. The Engine Computer controls the idle-down process in a way that simulates the old "dashpot" the classic cars had in the throttle linkage. I believe that if it thinks the car is in gear it will not perform the dashpot function and the car may idle down too fast and die.

There may be a better explanation than this for what I'm saying. I'm a transmission guy and not an ECM specialist!
Save Share
Reply Quote
mustangmommy05
You could always check your IAC, might just need to be cleaned.
Save Share
Reply Quote
sic 89 GT
I'm not sure about the safty neutral switch... I don't see how it would only affect it when the A/C is running or the IAC but weirder things have happened I supose... I'll check them out and see what happens. Thank you for your help
Save Share
Reply Quote
SPeace-ATL
sic 89 GT said:
I'm not sure about the safety neutral switch... I don't see how it would only affect it when the A/C is running or the IAC but weirder things have happened I suppose... I'll check them out and see what happens. Thank you for your help
Click to expand...
If the idle is right on the fence, extra load from the A/C can make the difference. Some cars don't care if the neutral switch isn't working and others do strange stuff similar to this.

Worth a try. the switch needs to be closed, or the two wires jumpered together to make it sense that it is in neutral. Switch unplugged, or missing can cause the issue. Some people have removed the actuator pin under the switch to make it sense neutral all the time.

There is no guarantee this is your issue,but it is a curve-ball that has affected a number of Fox Bodies...
Save Share
Reply Quote
sic 89 GT
Ok so checked all that and still no change... Someone here at a local mustang meet told me to try a 93 cobra maf... Found one for $20 and put it on... Idle is a little better but still dies when coming to stop with A/C running. Could it be the compressor going? Keep in mind it is the original 1989 A/C still R12 blows cold though:im confused:
Save Share
Reply Quote
sic 89 GT
Anyone else have an idea of what could be the issue?
Save Share
Reply Quote
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Ford Mustang Forum
A forum community dedicated to Ford Mustang owners and enthusiasts. Come join the discussion about performance, builds, modifications, reviews, engine swaps, classifieds, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
2005-2010 Mustang Talk 2011-2014 Mustang Talk 5.0L Tech Classic Tech 2005-2010 Mustang GT Tech
Top