This is the second time in a week it has done this, the first time on a fast 1 to 2 shift and this time on a fast 3 to 4 shift. I was moving along pretty good in 3rd, shifted a redline, threw it in 4th and stepped on it and it felt like it went into "safe mode" or something. According to the VAFC, full throttle was only showing like 10% throttle. I stopped the car and turned the key back for 5 seconds and restarted it and it was fine

It sucks cause I was dead even with an 08 WRX too (on a track, of course! ) Anyone experience this before?

 

Bump, please help. Would like to know before I go to the drag strip sunday!

 

bad fuel? pump might be dieing? Put some 100 oct at the track and report back with the results.

 

I wouldn't think it would be the fuel pump, cause it's only when I tach it out and pull a really fast shift. I don't know if the ECU thinks something is wrong from the fast gear change or when I punch the gas right awterward or what. I don't know, only does it than.

 

failing MAF?

 

Would a failing MAF cause the car to go into some kind of safe mode? It's just weird that after it happens, flooring the gas pedal registers as 10% throttle on the VAFC and after shutting the car off for 5 second, it works fine.

 

A bad MAF would cause it to go into safe mode for sure. But the 5 second thing idk what the hell that is.

 

You're over extending the throttle.

When you floor the pedal the VFAC should read UNDER 100% throttle. If it goes up to 100% it will go into limp mode and do exactly what you're describing. It will stay in limp until you reset it by shutting it off and back on.

Did you see the VFAC read around 80-90% and "adjust" the pedal by bending it up till it read 100% when floored? If so that's the problem. Adjust it back to where it was and leave it alone. Don't ask me how I know this

If not then check if the pedal can be pushed to the right or left of the stop when really pushing it hard. With the ignition ON and the car not running floor it hard and see if you can get the VFAC to read 100%. If so that's what's kicking you into limp mode.

There's also a TSB for the pedal stop.
The pedal stop behind the gas pedal will let the pedal slip past it and go too far.

 

Damn! Thanks for the info!! Just pushing normally and not hard at all, the VAFC reads 100%. So basically, I'm just hitting the gas too hard after the shift?

 

Yeah, the pedal is moving down too far. It's natural to press it harder when racing.

You should adjust it so no matter how hard you mash the pedal it
only reads in the high 90% range. That way you can be sure it won't go into limp again. Mine reads about 97% with me pushing as hard as I can.

There's no power to be found by opening it more than that. The computer is only going to open it so much any way. It's not that you're actually opening the throttle more, you're just overextending the drive by wire sender under the pedal. When it reads over 100% it thinks there's a problem with the sender and puts it in limp for safety reasons.

 

Thanks man, you saved me from a lot of worrying lol how would you adjust the VAFC to read a lower number for throttle position?

 

It's not the VFAC. You need to either bend the pedal down a little or raise the pedal stop. The VFAC has no control over the throttle.

You can put a couple washers behind the pedal stop to shim it up some. That's probably the easiest fix.