Growing RPM with pressing accelerator - Ford Mustang Forum
 
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post #1 of 14 (permalink) Old 08-08-2012 Thread Starter
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Exclamation Growing RPM with pressing accelerator

Hi,

I have the next issue for a quite a long time and do not really know what to do.

I have 2007 mustang gt with procharger on it. GT500 fuel pumps,exhaust etc.

While cruising and pressing of the accelerator the car will continue to handle the speed like i am still pressing the pedal. If i will press the clutch the rpm will grow. But while cruising with the pressed accelerator my vacum will be around 10-12 psi, pressing off the pedal vacum will be the same like in idle 22-26 psi.


I really do not know what to do with that. It is not connected to tune anyhow as the same issue apper in default Predator tune and custom tune with the SCT programmer.


Any ideas?

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post #2 of 14 (permalink) Old 08-08-2012
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I don't really understand what you're asking. You've noticed that you're pulling more vacuum at idle or off-load (clutch pressed in) than when you're under load? That's what all internal combustion engines do.

You mention vacuum but are you concerned about boost? A properly configured supercharger will not make boost with no load either.

post #3 of 14 (permalink) Old 08-09-2012
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If I'm
Understanding your question. It all seams normal.


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post #4 of 14 (permalink) Old 08-09-2012 Thread Starter
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Looks like i explained incorectly.

The problem is handling rpm without pressing any pedal. RPM will handle and even grow if i am not on gear without pressing any pedal.

That's the problem. The car accelerates itself.
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post #5 of 14 (permalink) Old 08-09-2012
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I would be checking out the bypass valve for your Procharger. Sounds like it's building boost. What was the last thing done to your car? Who was the last person in your engine compartment? Check all the vaccum lines. And btw, you can't say "my vacuum will be around 10-12 psi" that is like saying the light is dark. Boost is the absence of Vacuum. And it matters if you are in "boost" or "vacuum" as far as troubleshooting goes. Hell it sounds like that is your number one problem to me.
post #6 of 14 (permalink) Old 08-09-2012 Thread Starter
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Nope. I am not in boost. It is MINUS 10-12 psi and when pressing the pedal off it is falling to MINUS 20-26 psi. So it is definently not in the bypass as the car is not on boost at that moment.
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post #7 of 14 (permalink) Old 08-09-2012
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Well that changes things. Not trying to be a d1ck, but it is hard as hell to understand what you are saying. Will you car even make boost? You should really just make a video to point out this and post it up. And talk through it and say "I'm off the gas" or "I'm at half throttle and boost gauge is reading such and such"
post #8 of 14 (permalink) Old 08-09-2012 Thread Starter
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Sorry. I will make a video to show it up.
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post #9 of 14 (permalink) Old 08-09-2012
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Sry, just have to say, when I saw the subj for this post, my first thought was Um, yea, when you press the accelerator, RPM will grow.
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Quote:
Originally Posted by Monkey4now View Post
Sry, just have to say, when I saw the subj for this post, my first thought was Um, yea, when you press the accelerator, RPM will grow.
Lol, yeah I am pretty sure there is some language barrier/issues going on. Some of the things he said had me all over the place on what to think. That must be frustrating, but it is a little comical.
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thinking about my 2010 gt with a pro-charger makes my RPMs grow :-P

2010 Mustang GT, FRPP 3:73.1 gears, Paxton NOVI 2200 H.O. supercharger, SCT brenspeed tune, KOOKS LT headers, catted H pipe, SSS axleback exhaust, Comp Cams Detroit RoCkErS, brenspeed grind, DuPont SuperJetBlack re-spray w/ ChromaPremier clear, blocked down and buffed out, no orange peel! and a 3m clear bra.. It sounds like my Ducati 996 now. :-P
BHP? Lots, I guess...
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post #12 of 14 (permalink) Old 08-13-2012 Thread Starter
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Sorry for that. I mean WITHOUT pressing accelerator.

The car is in the shop right now so i can not make the video.

Is there any ideas what to check? Throttle body position sensor? Vacum leak? Anything like that?
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There is a function in the tune for this issue. My car was also doing this until I brought it to my tuners attention and he corrected it.
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