What does the TPS Narrow Range pot functionally do with respect to the engine's operations.

More specifically - what does the ECM do with the Narrow Range variable?

Thanks

 

on the older rotaries which had only a plunger-style narrow range TPS, the TPS was especially used to control solenoids in the ACV. I presume it is similar in the FD. Extrapolating between the series 3/4 and the series 6 cars, the Narrow range signals would for example tell the ECU whether the throttle has been suddenly closed. When the throttle has been closed suddenly, the anti-afterburn function of the ISC solenoid is engaged. There are also a bunch of other idle-related emissions functions in the ACV that the narrow range TPS is used for.

 

Thanks that really helps -

My FD stalled a couple of times when comming to a stop (AC on); I thought possibly the narrow range was out of adjustment or the IAC is not reacting correctly; never really knew what all the narrow range TPS did. Seems the anti-afterburn is working correctly, however (smooth transition to idle).

I screwed the throttle stop dashpot in another turn and it seems to have helped the situation.

arghx - what tech manual did the page come from? My 95 manual has nothing like it; F20 is the intro to the OBD.....

Thanks again!

 

the illustration is from the service highlights document in the sticky. The service highlights documents are incredibly valuable for understanding many aspects of how the engine works. I have service highlights from the series 3, series 4, and series 6 (from the sticky) cars as well as the series 2 (2009) Rx-8's if you are interested.

The narrow range TPS has its origins in the Bosch L jetronic and Motronic fuel injection systems used on 80s Porsches. Those cars had idle and WOT switches, with no 'real' TPS. Many of the functions of a full-range TPS (acceleration enrichment for example) were incorporated into the logathrmic voltage output curve of the flapper-type airflow meters that were common at the time.

the dashpot makes a huge difference in the decel stalling problem if it is adjusted correctly. You just have to adjust it a little at a time.