440 LSX 08 ZO6 1st pull clean, 2nd pull high RPM flutter

[FastEddy]

Very strange situation with this car and I'm having a hard time figuring it out. It's an 08 ZO6 w/ a solid roller 440 LSX, ETP LS7 heads, etc etc. Car and motor were built by very reliable sources, so it doesn't seem to be anything mechanical. I've just got this weird issue where it pulls clean all the way to 7000 the first pull you make after starting it up, but if you make a second pull, usually around 6800 I'm getting some sort of flutter. Almost like acceleration based limiting. I've tried changing the filter coefficients to minimize the effects, but I'm still getting the same issue. If you turn the car off and try again, the first pull is always clean, and the second pull always hits some sort of flutter around 6800.

I'm not really sure what it could be. They originally thought the car had valve float, but the valves have been ran correctly and everything seems to be in place mechanically.

Here's the current tune, and a data log of back to back runs. First run was clean to 7000, second run started to flutter and fell off on the dyno at 6800.

BTW. The car has FAST 60# injectors, haltech cold air, and American Racing 2" headers. it's a fairly large cam with 13:1 compression.

[4evervette]

what kind of rocker arm.. stock ?

[IDRIVEAG8GT]

Spark plug gaps.

[10_SS]

whatever it is, might be happening on bank two, according to the O2 readings.
Bank 1 and 2 are solid smooth all the way up to 7000rpm on run 1, then run 2 shows Bank 1 very smooth, and Bank 2 "swinging" a bit right around the area your mentioning. Unless bank 1 and bank 2 are controlled separately under WOT, I would start looking at coils, plugs, wires, injectors, etc. It could be slight miss-fire? I think that causes lean 02 readings. Could it even be the position of the spark plug in relation to the electrode in the cylinder.. never had an engine rev that high so never had practice at those RPM's.

Maybe swap some parts with bank 1, cylinder by cylinder to see if it eventually follows.

[vette_c6]

Fix your Wideband 1st of all
connect read the AFR .. its on 13.*

MAx your engine trq mang

disable the test for the map sensor


shot us with other scan

log your MAF hrz

[Xjas]

Sorry for the noob question but how are you controlling fueling on this engine above 6000RPM? that tune appear to me to be running in pure MAF mode but you are peggin the MAF at 511.99g/sec at 6000RPM so I thought above that the ECU has no idea how much air the engine seeing?
Have I missed something?

[HoP]

maf is pegged at 6100 rpm's. upgrade the os

[MikeOD]

Sorry for the noob question but how are you controlling fueling on this engine above 6000RPM? that tune appear to me to be running in pure MAF mode but you are peggin the MAF at 511.99g/sec at 6000RPM so I thought above that the ECU has no idea how much air the engine seeing?
Have I missed something?

maf is pegged at 6100 rpm's. upgrade the os

What both of these guys said is the first place I'd look. I think you're actually pegging the MAF somewhere around 5700-5800 RPM. Fix that first and I bet things will be a lot easier. I see quite the a matching jump in your PE table right between 5000 and 5250 RPM...and to be honest I'm not quite sure how it's able to fuel remotely close to right with those 2 things going on.

[t56rebuilds]

O2s look slow also, pass side is defintley slow, How old are they?