Unintended Acceration

"Bigdaddybry, Are you saying that the RPMs kept climbing even after you let off the throttle? If so, then yes, it’s some kind of throttle issue. If you’re saying you were trying to accelerate and it went to the limiter, it may be that the clutch is slipping. So the question is, we’re you on of off the throttle when it actually happened? Did it feel like it was in neutral? Or was it haulin ass?

Ans: Yes, RPM's kept rising even after removing my foot from the accelerator. Only stabbing the brakes finally brought it down. Doesn't happen all of the time but I've seen it enough now to know what to do when it does. Still, it's rather disconcerting when it does do it. I have an auto so definitely not a clutch problem. And yes, I was haulin ass in the middle of a tuning run at around 5700 rpm in 3rd. I've been working on cars for over 40 years. This is the only car I've ever seen that does this. I've checked everything I can think of (Throttle sticking, accelerator, carpet, wiring, etc). All of it checks out. Other than the one issue, the car runs perfectly. Just this weird full throttle delay release behavior that no one seems to acknowledge exists. Doesn't bother me really but you need to be aware that some of these cars have this problem. When it does a quick stab of the brakes usually will get it under control (at least that's my situation). Anyway, that's my story and I'm stickin' to it.

msvela448 said:

You are the first person I've heard that is using a device to change the throttle ramp rate. I'd venture to say that is most definitely your problem. Take that thing off and see if the problem happens again.

By the way... Why not just use a handheld tuner? Ask the tuner you use to change the throttle ramp rate in the tune so you get the response you are looking for... No trickery by a third party device... It's just written into the tune using Ford's computer so all the safeguards are in place for a drive by wire system.

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^This. Not to mention other things that can be improved via a tune. Remove that device and discard it.

I had this problem yesterday! stepped on the gas to overtake,depressed the clutch to change gear and the revs didn't drop! It's the 3rd time it has happened in the last 3-400 miles (car is just over 37k miles) and yes, I have checked the floor mat!
Going to take off the TB and give it a clean as the problem only seems to happen when close to or at WOT

I've used the SprintBooster before as well as driven with a few cars having it installed. No issues what so ever with the device, but a tune is of coarse a better solution to the throttle response.

For the RPM climb, how many miles on the vehicle? Sounds like a throttle issue or potentially fuel. What setting was the SprintBooster set on, i.e red 1, green 3,...? How's the cars idle?

saleen836 said:

I had this problem yesterday! stepped on the gas to overtake,depressed the clutch to change gear and the revs didn't drop! It's the 3rd time it has happened in the last 3-400 miles (car is just over 37k miles) and yes, I have checked the floor mat!
Going to take off the TB and give it a clean as the problem only seems to happen when close to or at WOT

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I've been experimenting and found that if I'm planning to run the car hard that I can avoid the throttle sticking if I do a couple of quick 3/4 - full throttle blips. That seems to help alleviate the sticking behavior at full throttle. My advice; when it does happen just keep it in gear and stab the brakes to slow down. In my case the throttle releases immediately and engine RPM's come down normally with no ill effects. Still haven't traced down a cause but at least it's something I'm aware of and able to handle. Only concern is I plan on handing the car down to my son after he completes college so I would like to figure out what the Sam Hill the issue is before he gets it.

DieHarder said:

I've been experimenting and found that if I'm planning to run the car hard that I can avoid the throttle sticking if I do a couple of quick 3/4 - full throttle blips. That seems to help alleviate the sticking behavior at full throttle. My advice; when it does happen just keep it in gear and stab the brakes to slow down. In my case the throttle releases immediately and engine RPM's come down normally with no ill effects. Still haven't traced down a cause but at least it's something I'm aware of and able to handle. Only concern is I plan on handing the car down to my son after he completes college so I would like to figure out what the Sam Hill the issue is before he gets it.

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I had to pull back in behind a car that was going slow so had to stomp on the brake a bit hard,the throttle released immediately

Those sprint booster or any other kind of throttle thingies don't do anything you can't do through tuning or simply by pressing the pedal down further/faster. There is no improvement in throttle response that can't be duplicated with your right foot.

With that said I wonder if you might be able to capture the occurrence in a data log. I'm curious as to what if shows in relation to pedal position/signal and the actual TB blade angle. I mean if there was a big difference it should throw a code. Meaning if you let off the gas and the ECU knows this, yet your tb blades stay wide open, there would be a code, no? So I think that the pedal output signal is what is messed up. Whether its the floor mat or a busted potentiometer in the pedal assembly itself, IDK, but it's the only thing that makes sense to me.

Point is Saleen 836 and I are Not using sprint boosters. This behavior is inherent in the system. Cannot say at the moment if it's a drive-by-wire issue; some weird delayed loading programming issue or what it is. We know it's Not the carpet. I can remove my carpet and still get the same behavior. It only happens when you're really on it under load before you've reached maximum torque (the car is still under load working to satisfy a full throttle input). Then, when you let off of the pedal nothing happens; RPM's just keep rising as if the system is still trying to satisfy the last throttle input. Cannot remember if the pedal returned to normal position or not. In either case very disconcerting and dangerous if you couldn't get it under control.

I've checked; rechecked, removed and cleaned everything in the circuit. It doesn't happen all of the time. No problems with partial throttle or normal day-to-day driving. No issues with the gas pedal, throttle body or electronics that I can find. Only happens every so often and only under full throttle conditions. Since I have a data log setup I'll see if I can't recreate and capture an instance. If I do I'll send it to Lito and share with the forum for SA.

For now I know how to handle it. A quick stab of the brakes and the throttle releases...RPM's come down and the system behaves normally. Can't say why but I'm thankful it does and I don't have to listen to my engine bounce off of the rev limiter or worse. Haven't had a repeat since my last tuning run but I haven't really been on it since then either.