EFIDynoTuning Forum

Thank you for the explanation. Most of the functions i listed are either blank, or the comment is just the function number. FN1321, 1322al/dl are good examples of that. With my manifold volume at 3.25, its pretty dialed in. The tip in stays in the high 14s to low 15s but I still get the lean spike for a split second right before snapping back to normal AFRs after shifting. This is where i am stuck because moving manifold volume either makes it too rich or too lean on tip in. Changing manifold volume isnt resolving the issue so Im not sure where to go. I feel this is the 95% youre talking about. I believe at this point, I need to mess with the accel time constant to lengthen the time the transient fuel time for just a little longer than it does now. I believe that will get rid of the lean spike. Im assuming I would increase decel if its going rich on tip out and reduce it if is going lean on tip out and I would probably adjust it after getting accel time constant dialed in. Am i on the right track?

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Ok, I’m not sure I can be helpful here but reading this I’m just thinking maybe we are fighting a mechanical system and/or a parameter in the tune

A: Possible injector lag (mechanical) I have no idea how this can be discovered outside of replacements

B: Possible MAF reversion (mechanical) record MAF data log

C: Possible Fuel pressure fluctuation (mechanical) monitor/ record fuel pressure either mechanically or via input if available

D: Transient Condition Functions (electronic control) Obviously that’s why we are here and I’m just cutting my teeth with basic tuning so I lack something to add here.

I hope maybe this might help

I do not have injector lag issues. My injectors are genuine siemens injectors purchased from a trusted siemens dealer. They probably have less than 10k miles on them. I believe I use the same vendor Decipha uses. The lag that Decipha describes earlier in this thread does not seem describe the issue i am experiencing.

My maf is pretty far from the throttle body down in the fender well. I do not believe maf reversion is the issue.

I have an AEM fuel pressure gauge and monitor fuel pressure. I also have a fuel pressure dampener on my rails which counteracts any weird spikes. My fuel pressure is definitely stable. The whole fuel system was revamped last year but Ive been having the issue much longer.

The lean condition and seriousness of the lean condition changed when I updated my transient settings with settings from the most recent .bin. Changing manifold volume has made significant changes and almost resolved the issue. its 95% there. These are all improvements after messing with transient fuel that I havent been able to make any real progress on in 3 years. Im pretty sure I just need to extend the transient fuel constants to fix it. Im off for the next 4 days and going to mess with it to see if I can get it dialed in.

So no matter what i set manifold volume to. I still get the lean spike after shift and it's worse the higher the rpm is before i shift when cold. If i shift at low rpm it barely happens. If i shift at 3krpm, it leans out to 1.16, at 4k, 1.20. thoughts of other things i can try? It's like the tip isn't happening for long enough because it doesn't go lean right away. Accel time constant is already close to max in a few cells, can i bump up the xmul so i can decrease the Accel/decel time constant tables to get more adjustability?

Anyone?