Engine stalls with AC on?
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Freshman User
Joined: Jul 2003
Posts: 45
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From: Piedmont
Engine stalls with AC on?
86 F-150 302 EFI (4spd manual)
Every time I use the AC or Defrost my idle speed goes down to about 400 rpm and struggles. Most the time it cuts off, this almost always happens when I slow down to make a turn and push the clutch in. Also, when I turn my steering wheel sharp at slower speeds 5mph or less the motor cuts off?
I have messed with the timing several times (basically turning the distributor to the left or right) but it doesn't help.
One other thing; the motor wants to cut off when I let out the clutch as well (AC or No AC)?
Any ideas on how to fix this? I know the clutch may be going bad but that wouldn't explain the idle problem.
Thanks!
Every time I use the AC or Defrost my idle speed goes down to about 400 rpm and struggles. Most the time it cuts off, this almost always happens when I slow down to make a turn and push the clutch in. Also, when I turn my steering wheel sharp at slower speeds 5mph or less the motor cuts off?
I have messed with the timing several times (basically turning the distributor to the left or right) but it doesn't help.
One other thing; the motor wants to cut off when I let out the clutch as well (AC or No AC)?
Any ideas on how to fix this? I know the clutch may be going bad but that wouldn't explain the idle problem.
Thanks!
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
I'm not sure how the 86 EFI system works, but it sounds like whatever bumps the idle speed up is not working. It would be the Idle air bypass solonoid in 87-up trucks, and could be the same thing on your truck, but since I'm not familiar with 86 EFI, I don't know for sure.
Senior User
Joined: Aug 2003
Posts: 122
Likes: 0
From: kansas
Factory AC? If so, whenever AC turned on or steering wheel turned increasing ps pressure ecm should bump idle up a bit to compensate for increase in load. Does engine idle up to about 1200 rpm,s when first started and then idle down to about 700? If not do you have to open throttle with foot to start? Sounds like idle motor getting weak. 87 and epnc probably correct.
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Freshman User
Joined: Jul 2003
Posts: 45
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From: Piedmont
Thanks for the solutions. My truck does have the factory AC and it idles around 1200 when it is first started then goes down to around 600-700 rpms. When I turn on the AC it goes down to about 400-500 and struggles every time the compressor cycles, which is 1 time every 5 seconds.
I got a chance to turn up the idle this weekend which helped a little. It now idles about 900 rpms after it warms up. Although it will still cut off if I turn sharp with the Defrost/AC on high. I wish I could have tried the IAC but I didn't get a chance to go to Autozone this weekend.
Also, what does 87 and epnc correct mean?
Sorry, I am a little slow on the wording. If it is the idle motor, then what should I do to fix it, replace it or repair it? Any ideas on how to check or remove etc?
Thanks again for all your help.
I got a chance to turn up the idle this weekend which helped a little. It now idles about 900 rpms after it warms up. Although it will still cut off if I turn sharp with the Defrost/AC on high. I wish I could have tried the IAC but I didn't get a chance to go to Autozone this weekend.
Also, what does 87 and epnc correct mean?
Sorry, I am a little slow on the wording. If it is the idle motor, then what should I do to fix it, replace it or repair it? Any ideas on how to check or remove etc?Thanks again for all your help.
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Posting Guru
Joined: Jul 2003
Posts: 1,486
Likes: 0
From: Independence, MO
you know your not suposed to adjust the idle screw, you probaly have a problem some where else, but just for reference if the throtle body has never been changed, then you shouldn't have to touch the idle screw. I would pull the codes and check things out. good luck DW
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