10' S/C Z06 Re-Tune on 93 help/suggestions

[Dannn]

I'm working on retuning a Z06 for a friend of mine that he bought a few weeks ago. Car was purchased with all the current mods, and had been tuned on 104 octane previously. He'd like to run the car on pump gas 93 octane. I'm not sure if I should just start from scratch, or try to continue with the current tune.

The car idles terrible regardless of 104 or 93. Its not really hunting up and down, but it sounds awful, and is very lazy. Timing is all over the place, and the car stalls really easy during parking and moving from a stop. I've read a bit on E38 idle tuning, and messed with it a little bit, but ran out of time. At cruising speeds around 1600-1800rpm, the car surges a bit.

I was able to pull roughly 6-8 degrees of advance out just so that it would be safe on 93, and verified it with a few pulls and got no knock retard.

It appears that the tune is setup MAF only, as high-speed enter is set to 400rpm.
Also, when plotting spark advance on a map, I see that we're maxing out the spark advance map at 1.36.

Fuel trims are way out of whack, haven't touched them yet as I'm waiting for a wideband and boost gauge for the car.

The MAP sensor is maxing out, i'm seeing 17.1psi for MAP, so I can only see about 2ish PSI of boost, however I know the car is making more than that, I just haven't put a gauge on it yet.
I see that the MAP scalar is set to an odd value between 1 bar and 2 bar. Not sure why.

Anyone mind taking a look?

Specs:
Forged LS7 9.6:1
Cam - 232/242 .648"/.648" 116lsa
MSD Airforce intake
ECS 1500 series centrifugal supercharger
60lb injectors
Long tubes
full exhaust/high flow cats

[joecar]

Has MAF table been corrected...?

Post a pic of MAF duct/plumbing.

Is FPR manifold-referenced or un-refetenced...?

What is measured rail pressure (measure with refetence hose removed)...?

[Dannn]

I'm not sure if the MAF has been corrected, the previous shop/tuner seemed pretty reputable so I would assume that its been changed. I don't have a stock z06 10' tune to compare it to for confirmation though. Working on finding one right now, not seeing anything in the dropbox repo.

The picture I'm posting isn't of the exact car, however its got the same exact S/C kit with identical map location.

Single fuel feed line so i'm assuming unreferenced, but if I recall, it has a boost-a-pump on it.

I'll measure rail pressure next time I'm with the car. I glanced at the IFR table, but didn't look too hard at it as I'm still trying to figure out exactly what has been changed compared to a stock file.

My friend bought the car already done, so we're still trying to figure out everything that was modified on it.

Thanks joecar.

[Dannn]

I found a correct stock file in the hp tuners repo, I was able to copy, transpose, convert, and paste the stock maf calibration into the tune and compare. It looks like its been modified a good amount. airflow is higher up until about 3350hz, then it falls quite a bit.

[joecar]

Make sure rail pressure stays at 58 psi (+/-1 psi) at all times (even when the boost-a-pump runs)(otherwise the IFR table will be incorrect).

[joecar]

You will need a 2-bar or greater MAP sensor (install it and set the MAP scaler/offset correctly).

BTW: use kPa for MAP, it will save your sanity.

[joecar]

60 lb/hr (7.56 g/s) injectors are rated at 3-bar...?

If so, then at 4-bar they flow 69.3 lb/hr (8.72 g/s)...

at deltaMAP = 408 kPa in B4001 I see 9.57 g/s (it should be 8.72*sqrt(408/400) = 8.82 g/s)... it's close.

[Dannn]

Will a 2bar MAP suffice even if boost goes over 14.7psi? Was gonna tell him to just get a 3bar from a ZR1. I'm sure i'll keep it setup MAF only under boost, but i would like to try and keep dynamic airflow down low for drivability.

I will check and confirm with a gauge next time I see the car that fuel pressure is in fact 58psi on the spot. Thanks for the info on the injector flow rates, I will correct that in the tune.

I'm really not sure how this car was tuned before with the stock MAP sensor, i'm assuming they had a temporary boost gauge in the car, but there isn't one currently installed, so no way to check boost levels.

Really appreciate your help joecar. Thank you.

[joecar]

If MAP exceeds 200 kPa then you will need a 2.5-bar or 3-bar MAP sensor.

MAP is used during both MAF and VE...

to disable VE you can set the dynamic airflow threshold to something like 400 rpm.