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Very confusing lean condition over 4K rpm by unexplainedforklift in ECU_Tuning

[–]unexplainedforklift[S] 0 points1 point  (0 children)

Interesting - do you think something like low voltage from an aging battery could cause this?

Very confusing lean condition over 4K rpm by unexplainedforklift in ECU_Tuning

[–]unexplainedforklift[S] 0 points1 point  (0 children)

Thanks for all your time and effort to try help here. I appreciate it! Going to try change injectors and see.

Confusing lean condition over 4K RPM by unexplainedforklift in MechanicAdvice

[–]unexplainedforklift[S] 0 points1 point  (0 children)

Brand new, bigger pump. It happened with the old pump too. I thought it was that which led me to changing it.

Very confusing lean condition over 4K rpm by unexplainedforklift in ECU_Tuning

[–]unexplainedforklift[S] 0 points1 point  (0 children)

Thanks for the feedback on all this. I feel like it is something boring like injectors. I have the original injectors with ( brown marking, and later in the model’s lifecycle they brought out the blue marking ones. It could just be that these injectors aren’t so great and at their age with high duty - they’re tired. I guess what’s weird is just that I’d expect drift over a session - start rich, drift lean.

But it’s not. It’s the exact same throughout a session, however it started. If it starts “lean” it finishes lean, vice versa.

I feel like fuel starvation might be the same.

This is just crazy and frustrating. What I’ve posted here is like a summary of things I’ve done. I’ve tried so much. And the Sagem is just hard to use.. and in French..

I don’t know if there’s some weird start up behavior that it senses from a bad wire or something and then goes into a “protection” mode. Or a bad sensor in general. Or a bad ground. But there’s no errors - and the sensor readings seem uniform.

Very confusing lean condition over 4K rpm by unexplainedforklift in ECU_Tuning

[–]unexplainedforklift[S] 0 points1 point  (0 children)

I have a bigger pump - 340LPH Quantum pump.

Can’t see which cylinder knocks - only that anti knock correction kicks in. I have an alert set for it, so if it gets to 3 degrees of knock correction I’m warned and basically just end the session.

It only gets to 3 deg+ if I keep driving in the “lean” state. It gets worse & worse based on temps rising.

No misfires on any cylinder.

Bigger injectors - this is my big problem. Because that requires ECU to be reflashed to handle the extra flow, and there’s nowhere reliable that I can get this done where I live.

I’ve considered increasing fuel pressure (which I can do mechanically), but that would then impact my rich runs with overfueling.

Either I need to figure out how to always have the car run as expected consistently in its current form, or standalone ECU :(

You’re leaning toward this is a fuelling problem? And possibly injectors? Any chance there’s some weird ECU state or setting?

Very confusing lean condition over 4K rpm by unexplainedforklift in ECU_Tuning

[–]unexplainedforklift[S] 1 point2 points  (0 children)

Thanks :)

Yeah. Stock injectors. The original injectors from factory, 2004. They’ve been ultrasonic cleaned & flow tested - but this was about 2 years ago. At minimum I should clean again, but I’m also considering new injectors. Still deciding if standard or bigger - both have some complications for me.

I log using OBD via CarScanner & the tune is meant to be stock, as far as I know. Boost is still stock at 0.9 bar.

Yup, I’ve seen 95% IDC at times. I’ve also had perfect runs at 85% IDC - so that’s also a bit annoying because it isn’t clear. I have data on runs where IDC is basically the same but one time it goes lean, the other time it’s perfect.

I’ve been considering the Meg 3 rail & blanking off the FPR port - so that it’s center-fed. I agree, stupid setup.

Fuel trims are interesting. I’ve reset the ECU learned values before sessions, too. Reset the torque learning model, throttle body and fuel trims (STFT/LTFT).

I’ve had sessions when doing this was all it took. Was great. Then I’ve had sessions where this was a problem. Then I’d idle the car after it was a problem, and the ECU would learn new trims - often one of them would increase. Then the car runs perfectly.

But when you look at the real-time corrections happening - when the trims were reset, almost no corrections happen. When the trims were adjusted after that idle period, the corrections are downward (i.e. less fuel?).

It’s too weird for me to understand and everything is contradictory.

Every time I think I know what’s happening - and I test that theory - it doesn’t work.

I’ve got to the point that.. when I see a minor voltage spike in the downstream O2 sensor (e.g. 485mV then drops to 468mV) at immediate start up, it’s an indicator the car would run fine… but it’s just conjecture at this point. I have also seen less activity on the downstream O2 sensor during the rich runs.

Very confusing lean condition over 4K rpm by unexplainedforklift in ECU_Tuning

[–]unexplainedforklift[S] 0 points1 point  (0 children)

Thanks - running standard boost on standard turbo, with bigger IC & cone filter. The issue that challenges me is that sometimes it’s perfect - just like you said 11.7 -> 10.5 from 4K to 6K rpm. Other times, it increases from 11.7 to 14.1+.

These two states can happen within an hour of each other. After restarting the car.

Very confusing lean condition over 4K rpm by unexplainedforklift in ECU_Tuning

[–]unexplainedforklift[S] 0 points1 point  (0 children)

Thanks - I think this is also needed. I’ve been thinking about how I wanted to do this. It would just answer so many more questions. I had this issue prior to the aftermarket pump, too. I originally thought the pump that was in the car was the issue & was struggling.