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Discussion Starter #1
So I was out testing the new suspension yesterday at an autocross and had something happen that's never happened before. As I was exiting the first corner in 2nd gear I matted the throttle to the floor and nothing.....it simply refused to go or anything. I had run 6 previous runs in the morning doing the exact same thing with no issues. It only happened in the afternoon and I was able to repeat it 3 times. It never happened in another corner, and it didn't do it when I left it in first through the corner. I know it wasn't a fuel starvation issue, it still had 1/4 tank left and I've run it much lower before. Any ideas on what it could be/solutions?
 

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So I was out testing the new suspension yesterday at an autocross and had something happen that's never happened before. As I was exiting the first corner in 2nd gear I matted the throttle to the floor and nothing.....it simply refused to go or anything. I had run 6 previous runs in the morning doing the exact same thing with no issues. It only happened in the afternoon and I was able to repeat it 3 times. It never happened in another corner, and it didn't do it when I left it in first through the corner. I know it wasn't a fuel starvation issue, it still had 1/4 tank left and I've run it much lower before. Any ideas on what it could be/solutions?
I've had a similar experience, but I have the A8.

I tried to merging into the highway and near floored it, but the car didn't accelerate any faster. This has only happened once to me.
 

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I forgot to add that in each instance as soon as I completely let off the gas and floored it again it picked right up. It's almost like it never sensed me pushing the pedal to begin with.

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I forgot to add that in each instance as soon as I completely let off the gas and floored it again it picked right up. It's almost like it never sensed me pushing the pedal to begin with.

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Same. Might be a hiccup with the accelerator instead of a transmission specific issue?
 

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Same. Might be a hiccup with the accelerator instead of a transmission specific issue?
Yea it's something electronic, I'm just confused why it happened at the exact same corner 3 different times. Also kinda scary for every day driving, go to pull out into traffic and all of a sudden nothing :surprise:
 

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I'm starting to hear that issue more lately myself. Unless you have a Cat, steering and pedal are "fly by wire" so must be something in the electronics. Maybe a flash is available or soon to come.
 

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I would still wonder a bit about fuel starvation if it happened 3 times in the same corner. I am not sure why fly by wire would hiccup only under that specific circumstance. Are you a stick or auto? Everything but suspension stock?
 

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Discussion Starter #8
I would still wonder a bit about fuel starvation if it happened 3 times in the same corner. I am not sure why fly by wire would hiccup only under that specific circumstance. Are you a stick or auto? Everything but suspension stock?
Stick and yes everything engine related is stock. If it was fuel starvation why didn't it do it when I left it in first thru the corner? I've actually run it out of fuel before and it never hiccuped until it was out, it just doesn't make sense.

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You sure it was not fuel starvation? Arrington warned me to make sure I keep more than a 1/4 when I installed my SC as it could cause a lean condition. Wonder if you try it again at 1/4 and then try to repeat as 1/2 tank?
 

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Discussion Starter #12
You sure it was not fuel starvation? Arrington warned me to make sure I keep more than a 1/4 when I installed my SC as it could cause a lean condition. Wonder if you try it again at 1/4 and then try to repeat as 1/2 tank?
No not positive it wasn't. Wish I had a fuel tank with me to have filled it up and tried with more in it. Just thought it was weird it only did it in 2nd and not also when I left it in first. I would have thought if it were fuel starved it would do it then also.

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I have had the dead stick in the Jeep twice and yeah I was trying to :jump to light speed" on to I 40 traffic. Wifes 2011 Subaru was the worst and she didnt like it enough to dump it for a newer one. The always told me it was traction control....on dry ground in a 4wd Subaru with 170hp.......

I suspect it something to do with engine torque management and your steering angle cause a hiccup.
 

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I forgot about the traction control possibility. I kind of assume you would have that off (if you can in your car) when racing.
First gear you are presumably at a much higher RPM then second gear when you hit the gas coming out of the corner. I have no idea what the fuel flow rate is, pressure varies, etc but I think if you are already up in fuel flow because you are in first gear you might be more resistant to going "flat" when you hit the gas.
 
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These cars do something similar sometimes if you stab the gas while in neutral (or clutch depressed). I guess it is a self-preservation thing programmed in the computer. I wonder if the engine management somehow "thought" you were in neutral.

A fix might be to trail brake and slowly roll on the gas in that situation.
 

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Discussion Starter #16
OK so I can say for sure this was not a fuel starvation issue. I just did a little straight line testing to try and replicate it and see when it does/doesn't happen. From a dead stop, short shifting from 1st to 2nd around 2k rpm and then flooring the pedal it will accelerate normally to 2500 rpm where it cuts back power until 3k. This is the only conditions it does it in. From a rolling start it won't do it. If I shift above 2500 rpms it won't do it if I slow down in 2nd to a crawl and floor it won't do it, if I start from a stop shift and do anything other than floor it nope. Even if I start from a stop skip 2nd and shift directly into 3rd then floor it it won't. Easy solution is to always make sure now that I keep it out of that rpm range, but still curious why the computer is cutting power under those conditions.

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Maybe it's pulling timing....drive train noise might be triggering knock sensor? Have you tried logging the engine while you reproduce the flat spot?
 

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Discussion Starter #18
Maybe it's pulling timing....drive train noise might be triggering knock sensor? Have you tried logging the engine while you reproduce the flat spot?
Was going to try that next. Don't have a data logger yet. Anyone know an android app that would do it? If it's driveline noise why does it only do it starting from a dead stop and not rolling?

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Was going to try that next. Don't have a data logger yet. Anyone know an android app that would do it? If it's driveline noise why does it only do it starting from a dead stop and not rolling?

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Dead stop puts more strain on driveline as opposed to rolling.

As for logging you can use a diablo sport, or HP tuner (requires a labtop). If your just logging you could use something like this:
http://www.auterraweb.com/android-obdii.html

I used it as a logger and code scanner for my Infiniti and GC. Maybe someone can chime in if there is a better unit.
 

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Discussion Starter #20
Can someone with a stock M6 scat pack try this out and see if you get the flat spot in acceleration?

* start from a dead stop
*shift from 1st to 2nd around 2000 rpms
*once in second put the accelerator to the floor
*See if you notice a distinct cut back in power between 2500 and 3000 rpms.

I've been thinking and wonder if it has something to do with skip shift as someone else said. Maybe something with the fuel mapping for those circumstances.

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