Bad Idle
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Junior User
Joined: Oct 2005
Posts: 58
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Bad Idle
The 93 3L aerostar idles very badly.
It fluctuates in RPM constantly while idling and while in gear, but still idling.
I thought it was IAC, cleaned it no difference. I dunno what it is, but i'm getting to think that it could be vaccum leak, however a fluctuation in rpm makes no sense.
I will try to record it and post it up.. I've been lazy lately
It fluctuates in RPM constantly while idling and while in gear, but still idling.
I thought it was IAC, cleaned it no difference. I dunno what it is, but i'm getting to think that it could be vaccum leak, however a fluctuation in rpm makes no sense.
I will try to record it and post it up.. I've been lazy lately
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
pull IAC electrical plug, any change in engine idle?...
check resistance of IAC solenoid coil with electrical plug off... ...should be 8-15 ohms approx...open infinity=open coil.
check for 12v at plug from PCM/ECU with key on engine running....Ford claims IAC canNOT be cleaned but many have success.
any loss of ATF in tranny=failed vacuum modulator diaphram. any ATF in modulator vacuum hose to intake manif. tree.
check for failed/lose gaskets on plenum and lower intake manifold...bolts often work lose...test with spray FI cleaner...speed increase=leak...semi permanent lock tite on bolt threads helps....torque wrench saves a snapped off bolt or pulled damaged threads...
check resistance of IAC solenoid coil with electrical plug off... ...should be 8-15 ohms approx...open infinity=open coil.
check for 12v at plug from PCM/ECU with key on engine running....Ford claims IAC canNOT be cleaned but many have success.
any loss of ATF in tranny=failed vacuum modulator diaphram. any ATF in modulator vacuum hose to intake manif. tree.
check for failed/lose gaskets on plenum and lower intake manifold...bolts often work lose...test with spray FI cleaner...speed increase=leak...semi permanent lock tite on bolt threads helps....torque wrench saves a snapped off bolt or pulled damaged threads...
Thread Starter
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Junior User
Joined: Oct 2005
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Modulator is bone dry.. I checked the hose to make sure it's good, and it is.
I checked resistance of IAC it is 10.8 ohms
I also noticed that the electrical connection to IAC is extremely corroded. So i cleaned it up and now the car idles extremely better. It fluctuates a bit at times for a few seconds and then idles normally.
Is there anything else i should check?
I checked resistance of IAC it is 10.8 ohms
I also noticed that the electrical connection to IAC is extremely corroded. So i cleaned it up and now the car idles extremely better. It fluctuates a bit at times for a few seconds and then idles normally.
Is there anything else i should check?
Elder User
Joined: Jul 2005
Posts: 560
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From: Houston,TX
that would probably only effect it after it comes up to temp...not at startup.
when is it happening?
and has it had time to reset the memory after you cleaned the contacts on the IAC?
when is it happening?
and has it had time to reset the memory after you cleaned the contacts on the IAC?
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Junior User
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This is occuring at all times.... I did remove the terminal for about 10 minutes and then tested it..
after that.. it idles much better.. however it still does it at times. It did it once when i put the car in reverese.. it idled so bad it almost stalled... another time it did it while i was waiting for the light to turn.. but it fixed itself after 3 or 4 seconds.
after that.. it idles much better.. however it still does it at times. It did it once when i put the car in reverese.. it idled so bad it almost stalled... another time it did it while i was waiting for the light to turn.. but it fixed itself after 3 or 4 seconds.
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Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
getting any codes now...CEL is not always set off by codes...
also, what is base rpm?...may be too low
may be intermittent sticking egr valve
also, what is base rpm?...may be too low
may be intermittent sticking egr valve
Last edited by 96_4wdr; Oct 23, 2005 at 12:01 PM.
Postmaster
Joined: Sep 2003
Posts: 4,452
Likes: 1
From: Southern California
Code 172: Running too lean. Most likely yor O2 sensor is out, giving a false lean signal. That's what happened in my van, the computer compensates by dumping in so much extra fuel, it fouled up my brand new spark plugs, causing the van to stumble/miss once in a while.
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
Last edited by 96_4wdr; Oct 23, 2005 at 05:39 PM.