It does sound like a vacuum leak. As a first step, have you cleaned the throttle body in case it might be sticking?
Weird idle hanging problems
My car has been doing something weird, and I can't figure out what's wrong. I have a 2007 Mustang GT(5spd manual) with a 91 octane performance tune, hot rod cams, 3.73 gears with limited slip and a cat back exhaust. Every time I come to a stop, I put my car in neutral like usual, but my RPMs will rise up to 1100 at idle, and then after about 5 seconds, it will drop to the regular 850 RPM at idle. Even if I put it into neutral at 1000 rpm it will still rise. Then, if I let my car just coast down a hill with no throttle and in neutral my cars, my RPMs will start to rise for no reason. I have been trying different things, but I have no idea. I think it could be a vacuum leak but what do you think? It drives me crazy because it happens every time I come to a stop.
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I have cleaned the TB and the MAF sensor to see if that helps. When I was cleaning the TB I noticed it had a little gap and wasn't completely closed I don't know if that has something to do with it. I also could have thought that one of my fuel injectors might be hanging up too.It does sound like a vacuum leak. As a first step, have you cleaned the throttle body in case it might be sticking?
I might check for a vacuum leak.
That's normal. The throttle body doesn't have an idle air bypass so instead, the blades stay slightly open at idle to supply enough air to keep the engine running.When I was cleaning the TB I noticed it had a little gap and wasn't completely closed
If you're suspecting a vacuum leak make sure the airtube is tightly sealed to the throttle body, and that the hoses attached to the intake manifold (PCV, brake booster) are intact.
Ok thank you I'll check to see if I can find a leak.That's normal. The throttle body doesn't have an idle air bypass so instead, the blades stay slightly open at idle to supply enough air to keep the engine running.
If you're suspecting a vacuum leak make sure the airtube is tightly sealed to the throttle body, and that the hoses attached to the intake manifold (PCV, brake booster) are intact.
You should also try to see if a trouble code is registered so I would get it scanned. It's free at any major auto parts store.
PCV valve hoses are a common problem for vacuum leaks. You can also spray carb cleaner around the engine as it's running to find any vacuum leaks. If you have one the engine should surge when spraying near a leak.
Does this car have an aftermarket CAI? If so, then I would suspect that it's delivering turbulent air to the MAF.
PCV valve hoses are a common problem for vacuum leaks. You can also spray carb cleaner around the engine as it's running to find any vacuum leaks. If you have one the engine should surge when spraying near a leak.
Does this car have an aftermarket CAI? If so, then I would suspect that it's delivering turbulent air to the MAF.
I have a shaker cold air hood scoop and a K&N intake.You should also try to see if a trouble code is registered so I would get it scanned. It's free at any major auto parts store.
PCV valve hoses are a common problem for vacuum leaks. You can also spray carb cleaner around the engine as it's running to find any vacuum leaks. If you have one the engine should surge when spraying near a leak.
Does this car have an aftermarket CAI? If so, then I would suspect that it's delivering turbulent air to the MAF.
You say that you put the trans in neutral when you stop, is it an automatic? If it is, why are you shifting into neutral when you stop?My car has been doing something weird, and I can't figure out what's wrong. I have a 2007 Mustang GT with a 91 octane performance tune, hot rod cams, 3.73 gears with limited slip and a cat back exhaust. Every time I come to a stop, I put my car in neutral like usual, but my RPMs will rise up to 1100 at idle, and then after about 5 seconds, it will drop to the regular 850 RPM at idle. Even if I put it into neutral at 1000 rpm it will still rise. Then, if I let my car just coast down a hill with no throttle and in neutral my cars, my RPMs will start to rise for no reason. I have been trying different things, but I have no idea. I think it could be a vacuum leak but what do you think? It drives me crazy because it happens every time I come to a stop.
To be clear whenever you push in a clutch your RPMs will normally rise slightly and then drop back down after a second or two after the clutch is released.I have a shaker cold air hood scoop and a K&N intake.
The Shaker could be a source for the problem. It looks really cool but there's no actual performance benefit to a functional hood scoop on a fuel injected car and would generally only cause possible problems due to more turbulent air entering the MAF.
Have you scanned the car for codes?
Who made the tune for the car?
From how he describes driving his car I assume that he has a manual then again he never did clarify whether it's a manual or auto.You say that you put the trans in neutral when you stop, is it an automatic? If it is, why are you shifting into neutral when you stop?
It's a 5spd manual. I have come to the conclusion that it is likely my tune. The tune is from BAMA Performance. I think that when they were making the tune It was set to "hang" a little so if I were to take the car on the track I can throw it into gear faster. I'll have to see if BAMA can send me a new tune to see if it fixes it.To be clear whenever you push in a clutch your RPMs will normally rise slightly and then drop back down after a second or two after the clutch is released.
The Shaker could be a source for the problem. It looks really cool but there's no actual performance benefit to a functional hood scoop on a fuel injected car and would generally only cause possible problems due to more turbulent air entering the MAF.
Have you scanned the car for codes?
Who made the tune for the car?
From how he describes driving his car I assume that he has a manual then again he never did clarify whether it's a manual or auto.
Bama isn't known to make good or reliable tunes. This forum is full of complaints.It's a 5spd manual. I have come to the conclusion that it is likely my tune. The tune is from BAMA Performance. I think that when they were making the tune It was set to "hang" a little so if I were to take the car on the track I can throw it into gear faster. I'll have to see if BAMA can send me a new tune to see if it fixes it.
Hopefully if I ask Bama to make me a new tune it will fix that problem.Bama isn't known to make good or reliable tunes. This forum is full of complaints.
Maybe, but your better option is to just go to another tuner and pay for a quality custom tune. Bama kind of sucks and apparently even more so when the required tune starts to get more complicated like in your case with cams.Hopefully if I ask Bama to make me a new tune it will fix that problem.
I've heard so many bad things about BAMA that I wouldn't trust them to tune a lawn mower.Bama isn't known to make good or reliable tunes. This forum is full of complaints.
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