Overrun fuel

[mattreay]

Hi,

I am experiencing a problem with inconsistent overrun fueling which I'm hoping someone can help me to understand.
Sometime fuel is cut during closed throttle decel but sometimes the engine continues to add some fuel. This results in slight rev hang if you dip the clutch, inconsistent deceleration and sometimes results in slight lean misfire under decel.

I have a JDM DC5 Type-r running ITBs and mapped using alpha-n on a K-Pro v4. Breathing mods only, standard internals and standard fuel system.
KManager version 4.2.6.0
Datalog and calibration are attached.

Frames 4660 - 4718 show the injectors continuing to run at 0% TPS and under deceleration. The overrun cutoff min rpm is 1300rpm and the minimum revs during this ranges are well above this minimum. However at 4701 the injectors are cut then restarted at 4706. I'm unsure why?
Similar behavior in the range of frames 5020 - 5090 where the injectors continue to run under decel.

The range 5420 - 5600 shows fuel being, correctly, cut entirely during deceleration.

I have tried ticking "disable fuel over-run cutoff delay" but this appears to make the problem worse as the revs hang, or even increase, during almost all gear changes.

Many thanks
Matt

[Hondata]

The TPS is not sensitive enough for small throttle openings. Around the 5:00-5:30 mark I can see the rpm & speed increasing with 0% or 1% throttle input, which should not be possible unless descending a hill. I suspect that you're getting 0.4% throttle and the ECU is firing the fuel injectors.
Also the battery voltage is jumping around a lot.

[mattreay]

Hi, thanks for your reply and analysis.
I was probably descending a hill at that point as I was certainly off the throttle from the drivers perspective, perhaps not from the TPS perspective though. Is there a way to see the raw TPS voltage from KManager?

I'll investigate the battery voltage fluctuation too, thank you. I guess I'm looking at a potential alternator fault as the voltage is fluctuating whilst the engine is running?
Could that cause the TPS signal to fluctuate slightly or should the 5V signal remain stable regardless?

Thanks
Matt

[Hondata]

Still I do not believe the TPS is sensitive enough. At 4:40 - 5:50 you accelerate for some time with 0-1% throttle. I don't think it is voltage or calibration - your TPS needs to read the throttle opening at a greater scale, especially for small throttle openings.

[mattreay]

Ok, thanks Hondata. I'll investigate replacing the sensor with a more sensitive one.
Many thanks for your help.
Matt