So say I turn up my boost with a mbc, I would want to keep an eye on my air/fuel ratios, timing pull, and maybe misfire count with vag-com right? What should the air fuel ratios be under boost? I know 14.7/1 is right for a NA car but does the engine need extra fuel for cooling? Also is there an acceptable amount of misfires or are any an indication of problems?

 

you should have 0 misfires. If you have any, you have something wrong. On a stock turbo, ~13:1 is about the norm for the a/f under boost. With a larger turbo, 12.5:1 is the leanest you should go with 11:1 being richer and safer. Best to keep it at 12:1 with a bigger turbo. You wont harm anything running it 13:1 like they do with a stock turbo.

If you have a AWP or BEA engine code, you can use vagcom to watch a/f, but if you dont, its worthless since the other engine codes have narrowband o2's and not that accurate.

 

Are you chipped or do you run a diode mod? Won't be able to do anything without one of those.

 

going to run the diode. I think the engine code is AMU. Thats a narrowband? Would a aftermarket wideband be the only way to know if things were safe or is there another function in vag-com that can be used?

 

I'm in the same boat as you. I have the AMU as well, it's narrowband.

 

Thats disappointing! Thanks for the info. Do run a chip or a diode mobius?

 

Another member took his 225 out to 20psi with a diode and the a/f was still in check. He used a wbo2. If you want an accurate reading, get a AEM wbo2 and gauge.

 

Interesting. Is that on a stock fuel system? If so I might have to crank it up to 18 or 19 psi until I can take accurate measurements.

 

yes, stock fueling

 

is the facts>followers a reference to modshack by any chance? I definately see where you are coming from if that is the case.