Fast Idle

Vettn71

Member
Joined
Dec 28, 2013
Messages
213
Reaction score
0
Location
North Richland Hills, Texas
Just had my a/c repaired (everything but the evaporator). Before this the car I idled at a steady 650 rpm, but afterwards it idles at 800, but stays at 1,000 rpm for a while. Thought it might be a vacuum leak, but don't see anything. Really seems odd. Could use some thoughts on this

TIA

Jim
 

MikeBo

New Member
Joined
May 15, 2013
Messages
48
Reaction score
2
Don't know if this helps, but my car idles at 800, maybe 650 was low?
 

94mustangsvt

New Member
Joined
May 31, 2014
Messages
45
Reaction score
0
Location
Oceanside, California
Around 700 rpm is typical for a stock idle. Try cleaning out your IAC valve with MAF sensor cleaner. They get dirty with age and can cause idle surging and sticking issues.
 

toyman

Active Member
Joined
Aug 25, 2008
Messages
874
Reaction score
9
ECU idle command for the manual is about 650 and the auto is 700 +/- 10 rpm. Vacuum leaks can be very difficult to spot and locate. The only sure way is to have a smoke test. The IAC cannot be cleaned other than cleaning the protective bellows surrounding the solenoid valve. The IAC is an open or closed solenoid valve. If it's the original it may be failing or not responding like it should to maintain the idle.
 

94mustangsvt

New Member
Joined
May 31, 2014
Messages
45
Reaction score
0
Location
Oceanside, California
ECU idle command for the manual is about 650 and the auto is 700 +/- 10 rpm. Vacuum leaks can be very difficult to spot and locate. The only sure way is to have a smoke test. The IAC cannot be cleaned other than cleaning the protective bellows surrounding the solenoid valve. The IAC is an open or closed solenoid valve. If it's the original it may be failing or not responding like it should to maintain the idle.

What year is your Mustang? I've pulled off the IAC valve, cleaned it out, and saw immediately improvement on about five different 94-95 5.0s so I beg to differ.
 

toyman

Active Member
Joined
Aug 25, 2008
Messages
874
Reaction score
9
What year is your Mustang? I've pulled off the IAC valve, cleaned it out, and saw immediately improvement on about five different 94-95 5.0s so I beg to differ.

'94 GT. As I said you can only clean the bellows protecting the solenoid valve and seat. Now, that's not to say there might be a lot of crud in the air passage and on the bellows which may affect air flow and the movement of the valve. However, you cannot clean the valve and the seat. So, if the valve is not seating properly or the electronics are not responding properly no amount of cleaning is going to help.
 

Latest posts

Forum statistics

Threads
77,713
Messages
1,508,437
Members
15,134
Latest member
Kodeblue

Members online

Top