P2746 - Mult Mix Adapt Min
P2178 - System Too Rich At Off Idle

First post! WOOO
Hello all.
Somewhat new here, been lurking for years now.

I have a 07 MCS with some minor mods done to it.
I recently invested in a Alta AP to make better use of the other mods I currently have.
I loaded on the Stage 1 FMIC map with linear throttle for 91 octane fuel or better.

Drove the car with this map for around 300-500kms and then one morning I went to start the car and it started like normal but then was running VERY rough. Almost like a boost leak but no such leak. The motor nearly stalled but came back to normal running state with a little throttle input.
At that point it threw 2 codes (P2746, P2178). I assumed this was to do with the very rough start and stumbling of the motor threw these as it nearly stalled.
I cleared the codes and began the drive to work. Somewhere along the drive it threw the P2746 code again but no CEL.
When I got to work I loaded the stock map back on the car for the drive home just to see if that was the issue but even then I had no power. Max boost was 4.5psi and would drop quick.

When I got home I checked and I have P2746 was back. I cleared the code and went for a drive around the block and the power was back. Pulled back in at home, loaded up the same map as before and went for another spin. More power and no issues and no codes.

So, long story short, does anyone have any insight into why I may be throwing this combination of codes?

 

I'm not familiar with Alta air inlet mods, but if the filter uses oil, there's a possibility that excess oil has contaminated the MAF. This might cause the ECU to use bad air / fuel ratios. Your AP can monitor this, both live and data log. Posting your AFR at various RPM's might help others diagnose your problem. Typical AFR's can be seen on many dyno charts, if you aren't sure what to expect.

 

Sadly I have not been able to log the starts or catch it in the happenings with my AP plugged in.

However I did give her a good thrashing on the drive home today. Just before I got home I had the cold side pipe blow off its quick connector at the back side of the motor. I'm thinking that the joint was allowing a leak to persist and having a leak like that on cols start would cause codes like I have been seeing. I re-connected the joint and went for a blast and it seems to run smoother now, no rough idle like before and powers back like it should be.

I did monitor my AFR the whole drive home and cruising i was 14.7ish the whole drive. Under heavy loads I saw as low as 10 (when hitting 19psi).