Bucking and Joe P FPR

[subachad]

On the way home through a spirited canyon drive, I noticed the car was bucking whenever letting off the gas going into turns. Is this a fuel thing or what??? Anyone else notice this and have a fix?

I just bought a Joe P FPR, will it help or is it completely unrelated?

The car is otherwise stock running 9psi. The temps tonight were in the 50's through the canyon.

Another question about the FPR. Why does it need to be connected back into the intake? Isn't it just a check valve to fool the stock fuel pressure regulator or map into thinking the car is not getting boost?

[acidbbg]

Please explain this bucking feeling? Have you ever owned a Manual Tranny..

B/c all manual trannys will jerk..some..when letting off the gas..depends on what rpm you are in..

chas

[Emode]

its the fuel things
its not caused by the FPR, its still from the shitty fuel maps
is your car stil stock?
i noticed it tends to get alot harsher when i upped the boost, before i got the flash.

is it occasionally when your holding the gas at a steady position, and as the boost falls off in the upper rpms, since your not increasing throttle, it will start bucking and shit ?

if it sounds like it, then i bet thats it. i never had the FPR but once i got the flash, it has almost always gone away, still some hesitation, but no more bucking

it also seemed to happen on slightly cool and humid days, around dusk


edit- i just reread that your at higher psi, so yeah the bucking was more pronounced for me when i did that, except i was at twelve

[subachad]

Yes I have owned Manual Tranny cars, quite a few of them and none of them did this. (85 and 87 Rx7, Talon Turbo, 69 Bronco, 93 Impreza) My guess is bad mapping in the ECU, hell my Turbo Impreza doesn't do it and I added the turbo. All it does is lets out a backfire under the same condition.

I haven't installed the FPR yet and am still wondering if that will help and if I can install it without running the line from the check valve to the intake.

It was both cool and humid last night

[MazdaDryvr]

I have noticed the same thing since I added boost. I'm at 8psi, peaking at 10. I have the flash and JoeP MBC. It seems to happen in 5th gear when I let off throttle quickly the car bucks. So I simply avoid sudden throttle cut and it's cool. :)

[subachad]

Well on the way home tonight I did some more "canyon tuning" and this is what I came up with. Turning the boost down to about 8.25psi peak all but fixed it. It was at 9 before that...

I also noticed that after driving for a few minutes it got worse. I checked the intercooler and it was cool to touch, maybe 50 degrees F. The turbo and "S" pipe on the otherhand were glowing red. This says a lot for the stock intercooler.

I think a hood vent would help the bucking. Also freeing up the exhaust should actually cool it down and help a little as well. Those with different exhausts, have you ever noticed this during hard driving? For example, an autoX?

[turboge]

The bucking is due to the fuel maps, when you dip into the gas then let off a little it has injected enough fuel to fill a bowl of cereal, it is flooded then ignites and bucks then goes back to normal.

That's it.