Hey guys, I really need some help. I have a ‘94 F-150
5.0 litre auto transmission. I would appreciate input
from anyone who has had this problem or has an idea
what it is. I have a low and inconsistent idle. The
truck often idles at around 400 RPM, sometimes it does
idle around 750 RPM. If I am running the AC on the
highway when I stop at the exit ramp it often stalls
due to the extra load of the air conditioning
equipment. It only stalls infrequently when not using
the air conditioner.

I did something today that gave me a nice consistent
idle at around 750-800 RPMs and I could even use the
air conditioning without stalling. I removed the
vacuum tube that enters the throttle body area from
the canister purge solenoid. Basically I think it let
a lot more air into the engine because you can really
feel the vacuum pulling the air. I know that is not
something I can continue to do because it is letting
unfiltered air into the engine but I wanted to see if
anyone knows what might need to be fixed to let more
air into the engine properly? From what I have read I
think the problem may be either the idle air control
(IAC), EGR system, or carbon in the throttle body.
Your recommendations are appreciated.
Thanks.
boatdude

 

I had the same problem on my 97 F150 4.6 liter, it turned out to be the IAC. Mine was stuck in the closed position and caused it to stall out.

 

Thanks *****,
I will try to clean the IAC this weekend. If that doesn't work I think I will replace it. Any other thoughts?
Thanks.
bd

 

I seem to be having basically the same problem with my 97 F150. When I am at a stop light or slowing to turn into the driveway the RPMs are very low (around 3000 rpm) and often the vehicle will die out...when I have my ac on it seems better since there must be something that raises the rpms to accomidate the ac. i have it in the shop for the second time and they cant seem to figure it out. they replaced the mass air flow sensor at $200 but that didnt help at all. i am wondering if it could be related to the transmission somehow. any help on this would be greatly appriciated.

 

Hi, I have a similar problem. I've got a 1997 4.6L V8, and a couple of months ago on a rainy night (it rarely rains in Arizona, so that's actually something I noted), my truck stalled a few times when going to idle. It would start up right away, but only stay running if I worked the accelerator to keep the rpm's up.

A couple of weeks ago, the same thing happened and sure enough it was raining again.

Here's the variable I just thought of: When it rains it's cool and I turn the A/C off, otherwise it's on all the time from May to October.

Now, however, even when dry and with the A/C running (or not), it seems to be idling at 400 rather than the 750 I always remembered seeing.

Any ideas? Thanks in advance.