m50b30ish Posted May 2 Report Share Posted May 2 The engine is an M50 with S52 crankshaft (89.6mm) and 85mm forged pistons 9:1 compression. M3 camshafts as well I have not verified timing with a light and I understand that is likely the first question for me. I am curious if my question can be answered without this info although I understand if not I have played with idle ignition, fuel, and idle control solenoid to reach target idle RPM in open loop With higher ignition timing and less solenoid opening I hit the target somewhat well although I couldn't tell if I was hearing a slight misfire. So my thought process was to lower the idle ignition target back to 10 where it started and this should lower chance of pre ignition. With a higher idle solenoid opening, less ignition advance, and a little more fuel the idle sounded to improve although still cannot tell if there is a slight misfire. I am wondering if I am potentially hearing unburnt (in cylinder) fuel escaping the cylinder on a very small level, similar to a pops and bangs tune but obviously less RPM. The idle ignition control would drop down to around 8 with the min clamp I had set. Would this be low enough to allow combustion into exhaust very slightly to sound similar to a small misfire? Please let me know if any conclusions can be drawn from this log. My AFR didn't seem to go high enough to cause misfire, however I am a novice and likely lack understanding all around. Thank you. idle help.llgx Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 2 Report Share Posted May 2 I dont see anything of concern in there, get the rest of it tuned first and leave idle tuning until last. An idle ignition target of 5-15 will work fine on nearly any engine and certainly a min clamp of 8 isn't the cause of your suspected misfire. I would typically start with a target of 10, min clamp of -5 and max clamp of 30. Proportional gain of 1.0 Quote Link to comment Share on other sites More sharing options...
m50b30ish Posted May 2 Author Report Share Posted May 2 Thank you, greatly appreciated. I will focus on the rest of the tune Quote Link to comment Share on other sites More sharing options...
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