Turbo C6 LEAN regardless of how much fuel is added via MAF or VVE IM LOST

[shoaf85]

Tuning a rear mount turbo A6 C6. The setup is very simple.

ECS Boost A Pump
ID1050x injectors
Rear mounted S475 turbo

The 3 mods listed above are THE ONLY MODS on the car period. I have tuned plenty of these setups without issue other than this being the first "A6" turbo car. I was originally going to tune it via MAF. I started pulls and the car does fine until it sees about 4-5psi then it goes lean. AFR is pretty solid up until that point. I was also able to dial in STFT at idle quickly via maf so I know the car is responding to changes. However I ended adding like 50% to the area in the maf curve where the lean condition is occuring. NOTHING. No change at all, even the INJ DC stays exactly the same. I was seeing 4+ grams of air readings so I just ditched the maf idea.

Moving on I decided to switch to a ZR1 map and go SD via VVE tuning. I converted the axis to read 2 bar vve and 7k rpm etc etc. Threw a base VVE table in from another car I had previously tuned with a similar setup. SAME THING, no matter what I do or command fueling wise the car goes lean as in .83 lambda to 1+ lambda as soon as boost comes in good. I even added 60% to the entire VVE table in the boost area and it had ZERO affect.

Before anyone asks YES I HAVE VERIFIED FUEL PRESSURE with mechanical tester on end of rail. SOLID 58-60psi the entire pull.

I'll add a few files from the maf tunes to the VVE tunes. Remember the scale was changed on the VVE tune to 210KPA and 7Krpm

The two logs are from when the tuning was being done VIA MAF. I didn't save any logs after that. Car is still on the dyno so if anyone wants to see a specific log LMK

Maf 1.hpt
Maf 6.hpt
2 bar vve starter.hpt
2 bar vve 2.hpt
d1.hpl
d2.hpl

[5FDP]

Likely not to fix all the lean problems but disabling desoot mode does stop some of the lean tip in problems people have.

Also why use the double stoich method when those injectors fix inside the 127lb/hr window that the OS allows? Aren't those 1050x like 113lb/hr at 58psi? Any past the like 500kpa can be flatlined in the IFR table.

Do you have another wideband sensor to try or can you calibrate yours?

[shoaf85]

I found the issue. Under the fuel tab there is an enable and disable tab for the Cylinder Gain, somehow (fat finger I guess) that was enabled. It is disabled in the oe file so I switched it back and boom that was it LOL. Shame 4 hours has been wasted but now I know.

The IFR for these 1050 was way above the 127 limit at around 430 KPA so I went ahead and did the double stoich method.

Everything is working properly now. First full pull was 549/550 on 7 psi and 10* .78 lambda (Dynojet)

[GHuggins]

Since it's available and turbocharged you might want to apply the 2bar OS patch to keep the baro from updating and causing fuel problems...

[shoaf85]

I typically do use the 2 bar OS on all my turbo tunes. I've used the ZR1 map with vve tuning once before and so far it has worked well. The car is monitored and I haven't noticed any fuel swings etc

[GHuggins]

You won't if your at a low altitude - it's those of us above sea level that see the big swings - I've got a baro of 90kpa here, so when it updates to 105kpa it makes for a nice 10% change - just keep that in mind for customers who might be driving up into the mountains every once in a while

[shoaf85]

Ahhh i see. Thanks man!