We just bought a used (obviously lol) 2001 V6 Mustang, 77K. Runs great but has one little annoying issue. The engine revs up every few seconds on it's own. If your idling it will be sitting there at about 650 rpm's, then every 3 or so seconds it goes vvVVrrrm up to about 1100 then back down. It also does it when your driving, like sometimes when you let off the throttle and push in the clutch to shift, you catch it right on a Vrrrm and instead of the RPM's dropping with the throttle off and clutch in, it Revs up another 500 rpms.
throttle positioning sensor maybe. Or your throttle cable could be getting caught on something. That's all i can think of.
or it could just need a tune up including new coil pack.
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When you own a V6 stang 3.8, 3.9, or 4.2 stroker, You're part of something different. You don't rely on a V8 to do your driving. Instead you learn the V6. You tune and tweak until you see GT's falling behind you.Then when they ask "Is that a V8?" You simply respond with a rev that clearly states "I'm a V6" with a proud smile on your face. As your girlfriend sitting on the seat next to you calls you an idiot.
"MAF" is the mass air flow sensor. Located right before the air box on the car.
An IAC (idle air control) motor is designed to adjust the engine idle
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When you own a V6 stang 3.8, 3.9, or 4.2 stroker, You're part of something different. You don't rely on a V8 to do your driving. Instead you learn the V6. You tune and tweak until you see GT's falling behind you.Then when they ask "Is that a V8?" You simply respond with a rev that clearly states "I'm a V6" with a proud smile on your face. As your girlfriend sitting on the seat next to you calls you an idiot.
Hey, it was cool today.. had the air conditioning off... it doesn't surge when it's off. Never thought to check that before. What does that mean then, maybe the air conditioning compressor is kicking on and off or something and changing the load on the engine? I do get cool air though, not ice cold but cool. But with the AC off, the engine idles smooth.
When you own a V6 stang 3.8, 3.9, or 4.2 stroker, You're part of something different. You don't rely on a V8 to do your driving. Instead you learn the V6. You tune and tweak until you see GT's falling behind you.Then when they ask "Is that a V8?" You simply respond with a rev that clearly states "I'm a V6" with a proud smile on your face. As your girlfriend sitting on the seat next to you calls you an idiot.
I never even thought about it, it's been hot every day, I hadn't had it off for weeks.. then we had a cold day and turned it off and bingo, no surging!
yeah pretty much.. if you think about it every time the a/c compressor kicks on it puts more load on the engine rpm's drop slightly.. then it takes a split second for the engine to adjust and then it returns back to normal.. same things happen in reverse when it disengages... load decreases.. rpms raise.. computer adjusts returns to normal
yeah pretty much.. if you think about it every time the a/c compressor kicks on it puts more load on the engine rpm's drop slightly.. then it takes a split second for the engine to adjust and then it returns back to normal.. same things happen in reverse when it disengages... load decreases.. rpms raise.. computer adjusts returns to normal
that does make sense, it's weird though as all my other cars, the compressor stayed 'kicked in' the whole time the a/c was on. One car did this when the freon was low, I wonder if that's what's happening...
well if its doing it several times a minute then i would suspect a problem with your a/c whether it be over or undercharged or something else failing.. but if its just occasionally i wouldnt worry
well if its doing it several times a minute then i would suspect a problem with your a/c whether it be over or undercharged or something else failing.. but if its just occasionally i wouldnt worry
it's normal for the compressor to engage/disengage a few times (or more) a minute because once it has reached its lowest cooling temp, it will cycle on/off so the compressor doesnt freeze up.
also, if the a/c is too low on refrigerant, there is a sensor that will not allow the compressor to engage.
wow ok, so yes normal then? It revs once every 3-4 seconds.
My old car did that when it was a little low on refrigerant, when off for that quick few seconds, pressure would build up enough to trip the sensor and engage it, then that would drop the pressure and it would dis-engage, ect.
I'm going to find where the fitting is and check the pressure, thanks!
2001 Mustang V6 surging 
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whats an MAT and an IAC?
