CTS-V surging after boost

[snax]

Hello gents,

Im working an 2009 CTS-v, ported heads, cam, ported blower, ported throttle body, intake, headers, 3" exhaust, 2.5" upper pulley, 9.55" lower pulley. Should make about 15-16lbs of boost with the pulley setup. Car made 620hp on 14lbs and 91octane.

Car came to us already tuned on pump gas, I loaded the custom OS for ethanol table switching with a switch hardwired to the ecu so he can switch between E85 and 91 octane. At the same time I installed ID1000 injectors, scaled them at 50% and doubled table B3671 (stoich AFR). Car ran great, trims are good but we were getting belt slip on the dyno. Today I changed some pulleys around (more belt wrap and should make a 1-2lbs more boost).

After a pull on the street the car started to surge badly while just cruising, you could completely remove your foot from the throttle and it would still surge. looking at the logs you can see throttle position going from 22% to 35% and back down to 22%. If you look at the WOT pull before the surge I noticed that MAF flow is upto 655.35 grams/sec.

I started the pull at frame 13639 in the datalog below and it first starts to surge at frame 14149 (does it twice there) and it surges a bunch from frames 14776 all the way to frame 15445.

Am I correct in thinking that this surging is because I have exceeded the MAF limit of 512 g/sec. Both tables C0803 and C0804 are maxed out at 512 g/sec.

Are my only 2 options at this point to install a larger MAF housing and retune the MAF tables or convert the car to speed density.

Is there anyway of scaling the MAF table B1099? what other tables would I have to also scale?

Here is the datalog and my current tune.

ctsv.efi
ctsv_ID850_COS-e85_0003.tun

[J.Abbott]

If you have a 09 CTS-V that has a E67 ECM an it is not limited by 512 g/sec. The MAF goes through a hard limit of 15000HZ with a max g/sec 3000g/sec. The factory tune @15000HZ is 2455g/sec.
So what is causing your problem, did you change the duty cycle for the boost blow off. More than likely you are hitting this and it is opening and closing which is the surge you are feeling. Go back to that table and fix it and you should be fine.

[Redline Motorsports]

I agree with Justin....you have enough MAF there for 2000 HP! Go back and put that stuff back and re dial in the MAF for starters.