Mass Airflow Readings

[Hi-psi]

Also, to provide an update. As I've continued to tweak the tune, I've got it to where almost all the high RPM WOT knock is gone. Where I'm at currently is pulling 3 degrees in the 1000-3800 range, and 7-8 degrees from 4000 up.

However, when I do still see any knock in my data logs, it still seems like it's occurring right after there's a pronounced/extended dip in the MAF reading. Maybe it's nothing or not related, but at least in theory if the MAF (for whatever reason) was dipping it's g/sec readings, that tells the ECM that less air is coming in, so it would then pull a little fuel back, thus momentarily going a bit lean when it really shouldn't have, causing the resulting knock.

But, I've also been known to over analyze things too.....so....LOL.

 

[justinesky]

why are you pulling so much timming? and when you adjust your LTFT, Are you matching it with the PE?

 

[Hi-psi]

why are you pulling so much timming? and when you adjust your LTFT, Are you matching it with the PE?

Well, I'm not sure it's really a lot. As I've progressed through the process of tweaking the canned Diablo tune, I get the feeling that untouched it's pretty aggressive on the timing curve/advance.



That's the final setup I ended up with. With that it runs great, zero detonation.

Now, according to the Diablo tuning tips, after lining out your LTFT's, the starting point for your PE adjustment should be 1/2 of your inj slope. I started there, -4, but was still way rich at WOT based on AFR. So, I just took another percent, then another, then another until the AFR's came up to the 12.8-13.0 range. Now, even once the inj slope and PE adj were solid, I was still getting high rpm audible detonation. So I started pulling timing little by little until it went away.

Going back to my earlier comment about untouched the canned tune being aggressive on timing.... Even after ending up with pulling 7 degrees 4k-5k and 8 5k+, I'm still seeing 20-23 degrees of advance in the upper rpms. If I approach that logically, that means that untouched the upper rpm WOT timing advance was close to 30 degrees which is pretty aggressive from what I gather.

On top of all of this is that although I have a new OEM fuel pump, I still have the stock 200k+ mile injectors which could very well not be performing at the top of their game and maybe their flow flattens off in the higher demand upper rpm WOT range.

Regardless, I'm happy with how it runs. Is it tweaked to the point of squeezing the last 5hp possible out of the setup, probably not. But it doesn't detonate one bit anywhere now, the AFR is just a hair rich which is safer, and it runs good.