Originally posted by WydRyd
Thanks John. Might check it out, but since I dropped the gap to 0.035", the subtle backfire on ignition off has disappeared.
As for my overly rich idle, my injectors checked out fine. I suspect my AFM is on it's way out... that'll be the second AFM I guess they just aren't designed for *any* kind of boost, especially over 1.1bar Must get rid of that fast and go MAP sensing asap.
What type of AFM are you using? I have successfully cleaned many hot wire units - it's not hard to do if you're careful. Also, if you're using a K&N filter (or other brand air filter that is oiled), be very skimpy when you oil the filter. Oil and hot wire AFMs do not mix well.
Last, if you have the ability to alter your engine management program, you can start to trim the A/F ratios at idle speeds. The typical Bosch Mass Air function will have voltage readings that correspond to a given mass of air. If you use a voltmeter and record the AFM voltage at idle (for a 5V Bosch system it should be ~1V), you can go to the Mass Air Transfer function and lower the air mass values slightly (10% max) and see if this helps.