TPS Function

[chris2712au]

if load is a function of rpm and airflow.. is the TPS just a correction like temperature ? and if you had an out of spec TPS voltage what effect would that have ?

as in 0.35 v rather than 0.5 ? although the idle ajustment seems to trigger at 0.35.. should I reset it ? I know the answer is yes but I would like to know the effect it would have being out.

[Eric]

The ECU sets the base/zero point at start-up/ignition, from the top of my head the only condition is that the voltage needs to be below 0.6 Volt.

Ideally the TPS should be set between 0.4 and 0.5 volt.

[chris2712au]

yeah I know it sets up the idle function for the idle stablisation.. and if it is set too low not only do you have to adjust it back to the correct voltage but you have to do the ignition five seconds on five seconds off 20 times to "learn" the new closed position of course when it is hot.. as the fast idle cam screws with the tps adjustment. someone said to me that it also effects timing ??? I would like to hear if anyone agrees.. and why / how..

[Legionnaire]

I always thought that it affects fuelling, providing acceleration enrichment? Dunno about timing effects.

BTW do you guys happen to know how to make ECU reset closed throttle position on R34 skylines?

[Fusion Ed]

Affects fuel cut on over run, cant see it affecting timing.

[Matt]

also found it puts injection limits (eg 1.5ms on Z32 ECU) when below a certain point and rpms above say 2000rpm

[FHCRSky]

Interesting subject.

TPS is there to stop lean condition (results in stumble when suddenly accelerating / during transient movement) when throttle body or throttle body's suddenly open, It's why a TPS is mounted on the throttlebody. TPS settings are usually played with after fuel maps have been tuned. Basically TPS = transient throttle enrichment.

TPS is a electronic version on injected engine of an accelerator pump on a carb engine. Does a similar job.

Pulled a R32 RB20DET Skyline TPS apart and TPS has a idle contact pin, curved track on circuit board for variable voltage, WOT contact pin. From what I understand and might be wrong, when TPS fails, tends to bend the idle, WOT contact pins (I gather due to foot to the floor and suddenly removing foot from accelerator pedal) and wears out the track on circuit board. I noticed how you drive car determines how long the TPS last's. I hear Toyota's have a optical version of TPS sensor and have always wondered if they can be adapted to run on Nissan's???

1st TPS failure: Felt like powerband moved down rpm's when accelerating on the street. That's the only way I can describe it. Below is the voltages from the failed TPS and new TPS and you can see the WOT voltage dropped.

This is the correct voltages (0.02V better than recommended specs at WOT, so a good TPS) from Nissan's Consult for R32 Skyline with RB20DET engine -

DEPRESSED : 4.02V
RELEASED : 0.44V
RANGE : 3.58V
SPEC : MORE3.0V

This is the failed voltages for TPS on RB20DET -

DEPRESSED : 3.60V
RELEASED : 0.42V
RANGE : 3.18V
SPEC : MORE3.0V

2nd TPS failure: Engine ran rich at idle and would randomly stall at lower revs (I assume engine flooded and stalled). Also you could wiggle TPS plug and engine stalled. I learnt it's best to set TPS on idle contact, even with a new TPS. If you don't, as you load engine up on a hill or turn aircon, light's, etc to put load on engine on flat ground and back off throttle quickly, revs can drop below idle rpm and sometimes not recover. I gather this is due to ECU not switching to idle tables via looking at idle contact pin on TPS. This is probably often mistaken as a idle valve problem when it's not.

I hope the above info helps.

[chris2712au]

Reset it.. the manual sr20 one has a learning proceedure... it was set at 0.39v... so I set it to 0.5 as per manual @ 80 deg C and then the tps idle disappeared.. then 20 on offs of the ignition key and it learne the new tps idle voltage.. it did make a transient difference.. especiall in the off boost areas when hot..