88 911 Throttle Position Sensor problem
 

So this TPS issue has been happening for about 2 years - I get on the throttle and nothing happens, then the back firing. I turn the car off and on and I’m back on the road like nothing happened. I’ve replaced the TPS with remanufactured sensors but they last from 6 months to a year before failing again. I’m on my 3rd replacement in 2 years (covered by warranty). When I replace them the problem goes away.

My mechanic has suggested changing the ignition coil which might be original and contributing to the problem but I’m skeptical this will help since replacing the TPS has always fixed the issue. I’ll probably go with a new TPS but wanted to get your thoughts. Anything else we should be looking at?

PS. Plug wires and spark plugs have recently been replaced (about 5k miles ago). Thanks!

It is not a TPS:

http://forums.pelicanparts.com/porsche-911-technical-forum/191911-function-tps-3-2-motronic.html

From a guy that knows his stuff:

"It's actually a 3 position microswitch, for Idle, Part Throttle and Full Throttle signalling to the DME."

1. Only two positions; idle and WOT, both are used (not a TPS which is a
variable resistor) used on later Porsche systems
2. has no affect on A/C
3. idle sw. - reduces injection time (basically zero) with RPM>1300 and Idle switch closed
4. WOT - increases injection time and ignores the O2 sensor
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Loren
Systems Consulting
Automotive Electronics