Porsche 996 C2, gas pedal fully pressed only 82% on sensor

[hakkiston]

Could anyone help me with this issue. Went to dyno today and got only 265hp. We noticed that when gas pedal is fully pressed sensor only shows 82%. Also the butterfly flap is not fully open when gas pedal is fully pressed

any ideas?

[logray]

The throttle body has a stop at throttle flap 80% IIRC.

It is not meant to open fully (and just because it isn't fully open doesn't mean that you aren't at WOT).

What year is your car?

[hakkiston]

The throttle body has a stop at throttle flap 80% IIRC.

It is not meant to open fully (and just because it isn't fully open doesn't mean that you aren't at WOT).

What year is your car?

1999 3.4l

ok. but I assume that throttle position sensor should be at 100% when pedal fully pressed and now only at 80%

Edited August 22, 2011 by hakkiston

[logray]

With the 1999 cable operated throttle, 80% is FULLY open (there is a stop there). It doesn't go to 100%.

I assume 265hp is at the wheels and not the crank?

[DanIelT]

265 at te wheels is pretty stout considering 296 at the crank!

[hakkiston]

Thanks for input!

265 at te wheels is pretty stout considering 296 at the crank!

no, this was not on the wheels.

My car is having some issues while full acceleration on 5000rpm and 6000rpm. Theres a noticable LAG on power input (like a second..) after the LAG car goes great again. This happens with 3rd -> 6th gear. I have ordered new MAF.

Maybe this LAG is causing dyno to show 265hp.

--

Sounds odd that its default that only the sensor shows only 80% when gas pedal fully pressed.

[Loren]

Sounds like MAF to me.

[logray]

If you're not so convinced of the 80% hook up your computer and monitor the throttle plate angle.

Go into the engine bay and open the butterfly until it stops. What do you read? 80%. Yep!

Also just another possibility for lag could be related to variocam...

[wvicary]

I have also seen readings of less then 100% on cable operated systems but in the range of 90 some percent. Is the cable and associated components in good condition and set correctly? Although I think your reading is low it's not the cause of your lag, MAF would be my first suspect.

[logray]

Gentlemen, I just went through this a week or so ago.

Hooked up PST2.

Opened butterfly by hand until it stops = 80% throttle plate angle.

Depressed gas pedal to floor until it stops = 80% throttle plate angle.

So 80% = 100% !!!!

[DanIelT]

Thanks for input!

265 at te wheels is pretty stout considering 296 at the crank!

no, this was not on the wheels.

Maybe this LAG is causing dyno to show 265hp.

So how is the motor being dynoed, out of the car on an engine stand?

[hakkiston]

MAF was bad. Also I changed from aftermarket Intake kit => Original airbox with K&N filter.

All working good now, thanks for replys!