Hot start issue C6 Z06 V3 supercharger+cam

[Pierrel]

Hi

2006 C6Z06 with V3 supercharger, small-to-medum camshaft.
"MAF only" as of right now, and 2 bar OS
Unknown specs of camshaft. Something around 230/250 duration on 115 LSA i think...
ID1050x injectors with their injector data.
Scaled 50% for injector data.

Having hot start issues. Car wont catch at first start attempt, but on the second it kinda catches, and oscillates for a bit before getting stable.

Attached log and current file.

On first start attempt it appears timing goes from 6 deg to -4 deg and it dies. After it has died, the TB moves from 27% to 15% a few times before the restart. Second time startup spark does not go negative, but oscillated wildly and takes almost 15 seconds to stabilize.

Appreciate any input.
Thanks!

[edcmat-l1]

At least part of the problem is you're still pretty far off on your overall fueling. Either something is off in the injector data or you just haven't dialed it in close enough. And the combo of that and the big fuel injectors causes an overly rich condition on startup that appears worse on startup.

And it's kind of pointless to use the 2 bar COS and set it up "MAF only".

[Pierrel]

At least part of the problem is you're still pretty far off on your overall fueling. Either something is off in the injector data or you just haven't dialed it in close enough. And the combo of that and the big fuel injectors causes an overly rich condition on startup that appears worse on startup.

And it's kind of pointless to use the 2 bar COS and set it up "MAF only".

I fully agree on it peing pointless using the 2 bar OS on "MAF only", will work on this as soon as i get it to start properly.

Alright, will continue to get the fueling right first. Do i need to get the VE table correct as well when in "MAF only"? I can see "Air calc mode" is Normal when cranking and then goes to high speed when its running.
Is my commanded cranking fuel too rich you say, or do i not fully understand what youre saying?

Injector data should be correct, scaled 50% and using Injector dynamics data for the 1050x injectors.

Is cranking fuel based of of VE? The VE table on this car is not looking stock. Is it better to get a stock VE table (VVE table with inverted axis) and start from there?
How do i get the cranking portion of the VE table correct? Will a histogram with EQ error get me the right data?

And a question on setting RAF / Airflow final min table. Do i simply plot DYN AIR vs RPM and also log integral and proportional airflow, with idle base timing and adaptives and use that data to setup the table correct? What about higher RPMs?

Thank you

[Alvin]

You should get VE nailed first. A lot of issues like this will solve themselves if the basics are done

[Pierrel]

You should get VE nailed first. A lot of issues like this will solve themselves if the basics are done

Thank you Alvin
Do i need to get the whole VE table nailed, or just focus on the lower parts (say 800 to 3000 rpm?). How do i get the cranking part of the VE table correct, or do i leave that stock and adjust cranking VE table?

[Cringer]

Cranking VE does not use VVE.
https://forum.hptuners.com/showthrea...l=1#post827160

Using big injectors makes hot starts even worse, the best hot start relief I have found is to retard EOIT Boundary for the 0 RPM cell.

[edcmat-l1]

Thank you Alvin
Do i need to get the whole VE table nailed, or just focus on the lower parts (say 800 to 3000 rpm?). How do i get the cranking part of the VE table correct, or do i leave that stock and adjust cranking VE table?

To make it right you should do the entire VE. The lower half with trims and the WOT with a wideband.

Here's the thing most novices and even experienced tooners forget. You first start with the most basic changes and tables to get it running. I can break that down to maybe 1/2 dozen, not including injector data if using bigger injectors. Then you're talking 10-12 tables maybe.

Then you need to dial in your airflow tables at operating temp. Once THAT's done so many other things fall into place. In E38s specifically, there's not a bunch of fancy adaptive tuning, alternate table tuning, etc. that needs to be done if all the basics are setup correctly.

A good quality tune file should be mathematically correct, make sense, and be done with minimal changes to be honest. A tune file with 100 tables changed usually means someone doesn't know WTF they're doing and are chasing baked in problems. It doesn't mean "they know their shit".