Very high idle
60

Asked by PHATBOY2002 May 13, 2015 at 06:32 PM about the 2002 Mercury Grand Marquis

Question type: Maintenance & Repair

Cleaned engine. Blew off, dried
everything, disconnected all wiring
connectors blew dry and reconnected
all wiring, hoses, and removed all
coilplugs blew out dried boots and
applied dielectric lube. Car starts and
runs great, EXCEPT IT IDLES AROUND
2000RPM!. I removed the tps,
disassembled it and it was dry and
functioning. Still high. I disconnected
the plug from the tps, still high and
throttle acts normal?. If I pull the lg.
Tube from the IAC to the intake hose
and plug the tube with my thumb,
normal idle. Put tube back into hose
and disconnect plug to mas and idle
drops to almost stalling then idles
normal. Any and all suggestions would
be great. ALSO NO CODES CAME UP
ON TESTER AND I ALSO REMOVED
THE IAC CLEANED AND
REINSTALLED. THANKS.

3 Answers
60

PHATBOY2002 answered 8 years ago

Thanks for your email Jim but I already ran the sequence in the owners manual when you replace or disconnect the battery. I followed and checked every vacuum hose and connectors, all seem OK. I think it is the IAC valve. I had a problem with the EGR system due to pack rats chewing the vacuum hoses a few yes. Ago. All lines were replaced along with a few control valves. This is the first problem ( with the exception of a new fuel pump last year) since all the mentioned repairs to vac lines etc for the egr. Thanks again. Fatboy2002

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60

PHATBOY2002 answered 8 years ago

I ordered one this afternoon. I should have it by 2:00pm tomorrow, AZ time. I let you know what the outcome is after its installed. Also when I took the car for a drive about a hour ago, I put 25 miles on it, it was hard to up shift without really getting on it. As I turned down my street it was doing 35-45mph without touching the gas pedal! What a ride!!!! Thanks again Phatboy2002.

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40

Crestline_782 answered 7 years ago

Hello, I am having the same problem with my car. The Idle is high and it won't come down. I just bought it and the battery was replaced about a year ago. It appears as though it has had this problem for a while. I was wondering, what is the sequence for the battery reconnection?

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