02NBMFormula

iTrader: (6)

Attached is the log of the 1/4 run that took out my ls1. I thought that someone might be able to shed some light on what happened.

Preliminary damage report is blown head gasket(white smoke, milky oil) and a busted # 7 piston (spark plug f'ed.) The bird is currently in the shop (Vengence)getting a built motor and i cant wait.

so what happened? denotated enough to kill a piston?

Frost

iTrader: (45)

No wideband, but going by the NBs, the car leans out at the top of the gears. The increase in cylinder temp caused the knock at the last shift... without meth, 18deg @8.5psi with stock SCR is a couple degrees higher at that shiftpoint than I have been able to run with very similar setups on the street. The AFR was likely a fair contributor as well, we just can't see it.


-edit-
470rwhp thru an auto with no meth is about the limit of a single walbro/racetronix pump. What does your wideband say up top? What was your fuel pressure like from 5200RPMs up?

1Hotbird

iTrader: (5)

Sorry for the thread hi jack, but can a log from Hpt be veiwed with EFI Live?
Or do I need Hpt to veiw it? Thanks

Frost

iTrader: (45)

Yeah you need HPT

1Hotbird

iTrader: (5)

I wish Hpt had a trial thing so us efi guys could see the logs from Hpt.

02NBMFormula

iTrader: (6)

when i had it dynotuned in august, afr was 11.7

i cant remeber what the fuel pressure was off the top of my head.

thanks for the help frost.

Frost

iTrader: (45)

Another possibility is, you are at the edge of maxing out your MAF. It could be in August with the warmer air, you were below it's ceiling, and now in the cold air it maxes out and you go wander lean up top.

....just thinking

radkon

iTrader: (2)

I see a bit of KR spike at (2.5) from frames 1429 to 1458 then a significant drop in all activity. While 2.5 isn't huge, I think that is where the damage was done.

02NBMFormula

iTrader: (6)

how would i go about testing this out??

Frost

iTrader: (45)

I just looked at your log again... previously my graph was showin the MAF output in freq, and I changed it to your g/sec (or lb/min) and see that in high gear, you actually max it out just a hair over 5K RPMs. Without proper 2bar tuning, your tuner is forced to manually add fuel in a static table that is blind to boost or the engine's need. If it is rich enough up top, this will ususally get you by just fine. If your AFR was 11.7:1 in august up top (rpm wise), it will be quite a bit leaner in cooler air. I have seen maxed-MAF PE fueling vary a lot with outdoor temp.

Frost

iTrader: (45)

Here is a shot from your log at WOT:

Note that

1. At the frame marked by the white vertical slider, you see your RPMs at 5052, you MAF is already maxed out at 439.2 g/sec.

2. The second circle obviously shows knock, but that aside, notice that your narrowband O2s both taper downward from that point (stock MAF table limit) indicate that the engine is leaning out.

02NBMFormula

iTrader: (6)

frost, what would you suggest doing since the maf is maxed out?? the bird is getting a new engine and i dont want to blow up this one. thanks again, i really appreciate it

Frost

iTrader: (45)

A real 2-bar tune so that your fueling is based on your boost and you are not MAF limited... or at the very least, if you run it maxed MAF (not the best way), 11.7:1 is way too aggressive up in maxed MAF territory.

edcmat-l1

iTrader: (10)

Def 2 bar SD. I have seen more catastrophic failures from FIs with scabbed MAF/PE tunes than probably anything else. Its just a shitty way to tune. And also unneeded with all the custom OSs and stuff nowadays.

Slowhawk

iTrader: (12)

Thats the problem right there -August tune. It was tuned in the hot weather,so when it gets cold out the fuel demand goes up and obviously something couldn't keep up.Also you can run more timing in the hot weather compared to cold weather.This is a common season to see motors blow with FI.

2 bar SD will definitely be better.

02NBMFormula

iTrader: (6)

thanks for the info.

what is entailed to swap to 2 bar??? i think i remeber seeing something about needing a different map sensor(out of a cobalt ss?) then some tuning im guessing???

Frost

iTrader: (45)

quite a bit of tuning actually

I like the 2 bar map that is pn# 12223861

ATLSS

iTrader: (7)

Who originally tuned the car?

02NBMFormula

iTrader: (6)

after i put the blower on, i shipped the pcm to exotic performance plus to get a base tune so i could drive it to a shop to get it dyno tuned. it was tuned by a shop in jacksonville that did a poor job tuning it. 416rwhp @ 8.5 psi. afr was was in the 10's. so i took it to vengence, they did a great job. afr was dead on 11.7, they fixed the tranny tables the previous tuner had messed up. i dont blame them at all, **** happens.

what about a z06 maf?? can they read higher?