Throttle Position Reading at WOT
 

My 97 2.5 (throttle cabled) Boxster is have trouble in closed loop, I’m running out of things to replace and my Porsche shop is lost. They think the problem might be the TPS it’s currently reading 80% open at wide open throttle. Is this normal?

I don't see how, on my 2000 S it reads at 100% at WOT. If the computer thinks you only have 80% throttle maybe it is restricting fuel?

Since you actually have a throttle cable, is the sensor on the throttle body? Maybe it is only opening up 80%?

These are probably useless and obvious thoughts... But I figured I would add them :)

Good luck!

It’s having trouble with the fuel map for sure. That’s really all the shop knows (they’re looking at fuel curves in real time) (MAF has been replaced twice during this process). The throttle is physically open 100% which we’ve verified.

Is the throttle physically at WOT, or is it that the accelerator pedal is at WOT? If the pedal does not reach full open throttle, try the adjustment at the cable elbow. I read that it is actually fairly common. Someone posted a good write-up a year or two ago on one of the forums, but I can't find the exact one. This one should help:
Non e-gas throttle cable adjustment?? - Pelican Parts Technical BBS

I've been searching for the post 78 mentioned and can't find it either. This is the best I can find. As an FYI my 98 shows 81% on the Durametric which is in the 79-82% range said to be normal in that thread. Pretty sure Loren was active in the other thread.

https://www.renntech.org/forums/topic/45038-throttle-cable-adjustment/

I’ve verified the throttle body is all the open and against the stop.

If the mechanical parts are working properly, then you may have a failing TPS (throttle position sensor) that is telling the computer that the throttle is at 80% when in reality is at 100%..?

nope 80% is what mine shows also. This appears to be the way its coded.

My student this weekend had a 1997 Boxster and I put the RaceCapture in his car Sunday, and noticed that the TPS seemed to have a few spikes to 86 but also several flat plateaus of 80, and I'm pretty sure he was at WOT. May be a cable throttle Boxster thing?

associated with this thread, yes?

http://986forum.com/forums/performance-technical-chat/71001-help-needed-odd-dyno-results-2-5l-time-trial-car.html

80% is correct on the cable throttle cars

i would suggest it's not the wot reading that is the issue, but possibly the readings it gives as it makes its way to wot - possible to log w a durametric?