PorscheDoc

So my car stranded me last night in the dark, started chugging and sputtering when I tried to get it above 2k rpms. Wouldnt die, and idles just fine, but when you blipped the throttle, it would get to 2k, sputter and go back to idle (same conditions when in gear, accelerate to 2k, sputter and you had to throw the clutch in to keep it alive). Left it parked on a side street overnight since i didnt feel like screwing with it in the dark. Today i went back, same symptoms. When i rev the engine (at the throttle body), the TPS does not click. When i unplug the TPS, the car revs normally, no problems at all, the idle drops a bit, but not bad. So i would imagine this is a bad TPS. Question is, can i unplug the TPS and drive it home (about 7-8 miles), or once the engine warms up will it start stalling out on me?

Travis - sflraver

The TPS is a switch that has two positions (3 wires). At idle it is at one position, during part throttle the switch is off and makes no contact and at full throttle it is in the other position.

The idle maps only run up to about 2k RPM and they do not take into account the engine load (AFM signal). The part throttle maps are full 3D maps that take load into effect and give the car fuel throughout the whole range of RPM. The full throttle is a full rpm range map as well but, like the idle maps, don't take load into account when deterring fuel.

What this means is that you should be fine unplugging it to take it home. With the wires unplugged its just like its always in part throttle mode (no contact).

PorscheDoc

Thanks travis for the quick response. Looks like i will limp it home later tonight

Travis - sflraver

No need to limp after you get it rolling. At part throttle it will be like nothing is wrong or missing.

PorscheDoc

Drove it home this afternoon without any problems with the TPS disconnected. Thanks travis.

TurboTommy

I thought one of the tests for TPS is checking if voltage goes up as throttle is opened. If, during the part throttle positons, the switch is actually off, how would this sensor give any readings?
Or, am I misunderstanding something here?

Bri Bro

The TPS pot is supplied 5 VDC and ground from the KLR. The output voltage from the pot will be between these two values. If the plug is off, there is no voltage going into the KLR. THe KLR reads a open voltage as zero volts. As the RPMs go up and the voltage still stays low, the KLR thinks to car is coasting (RPM>1600 and TPS voltage low).

Travis - sflraver

I took mine apart and there is only 2 micro switches in it. That was on a NA but I believe it is the same for Turbo.
Correct me if I'm wrong though.

Bri Bro

The TPS pot goes into the KLR on the Turbo. The NA doesn't have the KLR so no pot. The NA has two sets of contacts, the Turbo as one set of contacts. The main purpose of the pot is to generate a "full load" signal from the KLR to the DME by sensing the voltage on the pot.

Bri Bro

TPS NA

TPS Turbo