R34 "Use TPS sensor" feedback switch

[Smity42]

Hi Everyone,

I was just wondering if anyone knows what the "Use TPS sensor" flag does in "Feedback Switch 2" for an ER34.

It's been turned off on my tune, but my tuner doesn't remember doing it and neither of us know what it does.

I'm wondering if I should turn it back on?

Cheers,

Martin

[Matt]

Leave it on as that is factory default.

TPS sensor is undocumented. What I found is that when disabled the diagnostic sensor may be used as an input instead

[Smity42]

Thanks Matt,

What do you mean by the diagnostic sensor? Is this related to the "Diagnostic Idle RPM Control" value? Because I notice this has been changed from 0mV to 5100mV as well.

I've also found that if I enable closed loop (by setting the 02 feedback temp to 35), then the check engine light keeps coming on, although no code is thrown. If feedback temp is set to 255 then I don't get the CEL, but I also don't get closed loop .

I'm going to try enabling that "Use TPS sensor" flag and setting the diagnostic value back to 0mV and see what it does.

[Matt]

As before... undocumented. There is a diagnostic input to the ECU. I noted the code references this if the flag is enabled but that is all. It should be left alone

Diagnostic RPM control sets target idle RPM value in some ECUs. Default value should be 0

Try going back to factory flag settings. Sounds like something is messed up.

[Smity42]

OK I have made the following changes (all restored to factory defaults):

1) Set "Use TPS sensor" = ON
2) Set 02 Feedback Control Temperature = 35
3) Set Diagnostic Idle = 0mV

Closed loop is now working properly and CEL is not coming on .

I am just wondering with these changes - is my overall tune still going to be fine, or do I need to get it retuned?

[Matt]

Good question.

If the use TPS sensor was off, then the VE table may not have been accessed correctly and thrown the fueling out (would need to be checked with a wideband to confirm mixtures were the same as the AFR graph on your last dyno tun)

O2 feedback may be fine, since the trims were 0 (STFT/LTFT) then no difference to those said AFRs

Diagnostic idle should make no difference to the tune as I don't think it is used for idle target RPM adjustment

[Smity42]

Thanks again Matt!

[Matt]

Was looking at a tune for workshop today and noticed that the WC34 0V80F has the 'TPS sensor' turned off. Probably because second throttle body (and TPS sensor not used). So I think this one is for traction control

I did that compare flag request and displayed are the tickboxes after updating the software

[Smity42]

That's interesting.

One difference I noticed that when this flag was not ticked, when you applied the throttle from idle with the engine cold, it would try to stall. With the flag ticked however it works fine. So I think it's definitely better to leave it at the factory value.

P.S. Compare flag change looks great!