When your stang is Idling do the Rpms ever go Up and Down?
5th Gear Member
Joined: Mar 2004
Posts: 3,594
From:
RE: When your stang is Idling do the Rpms ever go Up and Down?
ORIGINAL: MantaDreams
when the A/C compressor cycles on and off, but usually in idle, and not to the point of dying on me.
when the A/C compressor cycles on and off, but usually in idle, and not to the point of dying on me.
the AC compressor kicks on wether the AC is on or not to circulate the oil in the system. this will cause the idle to be up and down. some cars have more of an RPM range for the idle difference than others.
The Godfather
Joined: Sep 2005
Posts: 15,480
From: Temple, Texas
RE: When your stang is Idling do the Rpms ever go Up and Down?
+1 Cobra, however, it will not cause a car to stall like he has had problems with. My 5.0 did basically the same thing, but was a little more severe. My car would start up fine cold, but would not start up fine warm, it would stuggle to hold an RPM and they would bounce up and down between 200-700, give it gas and it stuggled to run, though out the clutch and the RPMs would drastically fall, and hold it out, and it would probably stall.
Problem came out to be a bad EGR sensor, and bad IAC valve.
Problem came out to be a bad EGR sensor, and bad IAC valve.
4th Gear Member
Joined: Oct 2006
Posts: 1,526
From:
RE: When your stang is Idling do the Rpms ever go Up and Down?
IAC
it may be starting to go usualy they either stick and you revs wond fall when ideling they will always stay in one rpm say 1000 or randomly start reving iv seen the rev to 1500 and then fall all the way down and almost stall then go all the way back up
it may be starting to go usualy they either stick and you revs wond fall when ideling they will always stay in one rpm say 1000 or randomly start reving iv seen the rev to 1500 and then fall all the way down and almost stall then go all the way back up
The Godfather
Joined: Sep 2005
Posts: 15,480
From: Temple, Texas
RE: When your stang is Idling do the Rpms ever go Up and Down?
Well all Mustangs will have this happen because of the A/C, but generally the RPMs do not jump more than a couple hundred RPMs, it's when they begin jumping irradically, and the engine begins to struggle to run properly that the IAC may be at fault.
Gentleman's Relish
Joined: Feb 2005
Posts: 13,188
From: AZ
RE: When your stang is Idling do the Rpms ever go Up and Down?
IAC and also your throttle body and butterfly might need a good cleaning. A lot of times there isa ring of dirt that builds up on the TB where the bottom of the butterfly rests in its closed position. It needs a wee bit of clearance when idling. If this area has crud, the IAC has to compensate for it by holding the butterfly open a little more. Between the IAC saying what is good by default vs what the engine and computer are trying to tell it, you get RPM bounce.
Clean the IAC. Remove your intake hose where it connects to the TB. Take a clean rag with chemtool or your preference of TB cleaner, open the butterfly and wipe off the area around where the butterfly sits when its closed. You can look inside before you clean or feel with your finger that ridge of crap.
Clean the IAC. Remove your intake hose where it connects to the TB. Take a clean rag with chemtool or your preference of TB cleaner, open the butterfly and wipe off the area around where the butterfly sits when its closed. You can look inside before you clean or feel with your finger that ridge of crap.
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