rich idle question

[charofire]

Helping a friend dial in his idle with his m30 turbo (30lb injectors). How much will the air idle bypass affect the AFR at idle? He's running really rich right now (in the 11's at 750rpm). When I tightened his spring 3 clicks, the car seems to bog.

[tschultz]

In my experience you can adjust the idle screw on the AFM and bring AFR's down by about two points. Try it and see. It only takes an allen wrench or the appropriate width flatblade screw driver.

[charofire]

I helped my friend a bit more on his project this week. We moved the afm 8 clicks. It ran 14.5-14.7 afr at idle. But the moment he would touch the gas, it would immediately go to 10 afr. So totally bogs, and won't rev past 2k. Any other causes for such rich condition after getting the idle to run nice? He has 30lb injectors which is why he had to move the afm wheel a bit.

[T_C_D]

I helped my friend a bit more on his project this week. We moved the afm 8 clicks. It ran 14.5-14.7 afr at idle. But the moment he would touch the gas, it would immediately go to 10 afr. So totally bogs, and won't rev past 2k. Any other causes for such rich condition after getting the idle to run nice? He has 30lb injectors which is why he had to move the afm wheel a bit.

Is the o2 sensor connected yet?

[charofire]

Hey Todd, the narrow band is not installed yet. He's just reading off of the wideband. I figured the narrow band 02 would minimally be able to move such a rich afr. But if that's the problem, then I'll tell him to put it on today.

[turbodan]

Opening up the bypass screw should have a significant effect especially with increased spring tension. Set the spring tension so it drives well and dial in the idle mixture with the bypass screw. It is probably best to get it set right running open loop. There are limitations to what the oxygen sensor can do. If its trying to pull fuel when the engine is idling and then add it back in when you go off idle it won't run very well.