Strange idle speed problem solved
More Turbo
Joined: Dec 2006
Posts: 624
Likes: 2
From: FL
ok there is something still not right. next i would do
following -
-disconnect negative terminal on battery wait 10 mins. to reset computer then reconnect, start engine and turn on everything electrical and turn wheel stop to stop a few times then drive it stop + go etc
-when the warm engine is idling at 1000rpms unplug the electrical connector to the IAC solenoid. see if idle changes ie. drops
-possibly the new pcv (aftermarket?) is bad .. maybe try get a motorcraft one?
-bang head on wall
following -
-disconnect negative terminal on battery wait 10 mins. to reset computer then reconnect, start engine and turn on everything electrical and turn wheel stop to stop a few times then drive it stop + go etc
-when the warm engine is idling at 1000rpms unplug the electrical connector to the IAC solenoid. see if idle changes ie. drops
-possibly the new pcv (aftermarket?) is bad .. maybe try get a motorcraft one?
-bang head on wall
Cargo Master
Joined: Nov 2004
Posts: 2,858
Likes: 3
From: Friendswood, Texas
Please keep posting about this. Pulling the IAC connection while it's idling high is something I had not thought to do on mine. It's been replaced but I am now curious to know if this does anything to the high idle I get. Problem with mine is not that it idles high continually. Mine idles high when I come to a stop and continues to doso for 5 seconds or so before dropping to nrmal idle.
More Turbo
Joined: Dec 2006
Posts: 624
Likes: 2
From: FL
Originally Posted by texan2004
Please keep posting about this. Pulling the IAC connection while it's idling high is something I had not thought to do on mine. It's been replaced but I am now curious to know if this does anything to the high idle I get. Problem with mine is not that it idles high continually. Mine idles high when I come to a stop and continues to doso for 5 seconds or so before dropping to nrmal idle.
sometimes cleaning the IAC with carb cleaner will get it working agian if it's just gummed up with carbon etc
More Turbo
Joined: Dec 2006
Posts: 624
Likes: 2
From: FL
Originally Posted by texan2004
I just replaced the IAC and it still does it. I'm wondering if it might me a bad PCM.
also it may be that the computer needs to be re-flashed by Ford.
More Turbo
Joined: Dec 2006
Posts: 624
Likes: 2
From: FL
Originally Posted by michigan66
Reset the computer. High idle problem on initial cold start persists. Idle is normal on subsequent restarts.
is the MAF and the IAT sensor inside the intake tube clean?
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Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
My intermittent high idle, when coming to a stop, was traced to carbon deposits on the IAC plunger shaft, where it goes through the shiney baffel into the solenoid/electrical end. Cleaned that shaft real good & it has been ok for 4 weeks now.
So if the IAC cleaning or tests don't prove out, maybe suspect a sticking throttle plate.
Ford coats theirs with a non stick surface & doesn't recommend cleaning, so be careful of what you use & how you do it, so as not to remove or damage the coating, if you find it's dirty. I'd also remove it for cleaning, so you can see what your doing & no need to have the deposits or cleaner going into the intake manafold, or being ingested by the engine!!!!
If there are carbon or gum deposits on, or around the throttle plate, causing it to stick, it'll upset the idle rpm.
Edit: also check the throtte cable & throttle plate connections for damage, deposits, corrosion & inside the cab, for obstrctions around the gas pedal, like balled up floor mats, ect.
Just a couple more thoughts for ponderng.
So if the IAC cleaning or tests don't prove out, maybe suspect a sticking throttle plate.
Ford coats theirs with a non stick surface & doesn't recommend cleaning, so be careful of what you use & how you do it, so as not to remove or damage the coating, if you find it's dirty. I'd also remove it for cleaning, so you can see what your doing & no need to have the deposits or cleaner going into the intake manafold, or being ingested by the engine!!!!
If there are carbon or gum deposits on, or around the throttle plate, causing it to stick, it'll upset the idle rpm.
Edit: also check the throtte cable & throttle plate connections for damage, deposits, corrosion & inside the cab, for obstrctions around the gas pedal, like balled up floor mats, ect.
Just a couple more thoughts for ponderng.
Last edited by pawpaw; Jan 23, 2008 at 09:03 AM.