SiV6Qcoupe

The reason being my engine is running a few points lean at wide open throttle, more noticeable at higher speeds and also true at higher revs, especially at 4k when there is a distinct flat spot. My idle is lower at 600-700rpm rather than 700-800rpm too.

My air/fuel gauge confirms the flat spot by showing a drop -off the scale- below 'cruise' mixture,it returns after a second or two but never reaching the normal 'power' mixture untill the throttle is opened below 4k revs.
I have noticed that using the cold startup this problem does not exist with the added enrichment and power delivery is smooth right up the rev range.

There are FSE adjustable fuel regulator kits available for Audi models including the 12V V6 which contains the parts to add an adjustable regulator in the fuel return line and a linkage to replacce the stock regulator in the fuel rail. These are fairly expensive at UK £126.

An alternative adjustable regulator from Weber is available at UK £37 which also would insert in the fuel return line. Using this regulator the stock regulator would be retained as a safeguard against accidental over-leaning caused by the adjustable regulator. I would also consider installing a fuel pressure gauge to monitor adjustments.

There have been various comments made about the benefits of these devices but they are designed to benefit the 'modified' engine where air flow has been improved and the stock fuelling map adjustment limited. I look at this modification as an enhancement rather than a single 'power' modification.

I will post results in the weeks to come! :-)

cuatrokoop

any time you use an AFPR, it is very wise to use a good pressure gauge. also, what sort of A/F meter do you have? digital, LED, or ???? digital is the most accurate of the bunch, IMO. resolution is simply better. i'll be running one on my car in the future, as well as a FP gauge and boost gauge...

SiV6Qcoupe

I use a 10 LED meter that I built and calibrated myself, although I could convert the display to a digital readout but the LED's work best while on the move!
Can use a digital multimeter set to millivolts to monitor closed loop operation at fast idle for fine tuning.

What's the boost gauge for, turbo/SC?

ARK

Partially clogged injectors? or insufficient fuel pressure?