Sharing this in the hope someone has seen similar. I re-mapped my 200 with Celtic, and had timing and misfire problems with latching error codes. That got me into a long process and analysing with an OBD monitor. (Autel AL519). I finally decided to revert the mapping back to factory default.
Since reverting the map, I still get occasional misfires shown on the Autel, but they have not generated a latched error code. They are listed under On-board Mon Test; Mis-fire Cyl 1-4 Data; Misfire counts Last. I will get a few registered on any drive, but no particular cylinder is worse than another. e.g. short drive of 3 or 4 miles = 1 or 2 misfires shown for each cylinder. I think these are real, as I occasionally feel the car stutter on pick-up. These errors never latch and are reset when stopping the engine. On a long drive - 90+ mins - I might get 5 misfires per cylinder. (BTW - there are historical latched misfire values shown under EWMA Misfire Count (1 or 2) and these don't get reset on switching off the engine. I wonder if there is an easy way to reset those values?)
The other thing that I've noticed is the advance timing fluctuates a lot on idle. Under: Live Data; SparkADV degrees, on idle (e.g. 800rpm, no throttle) I will see fluctuating values from 9 to 21 degrees. If I apply a small amount of throttle to hold the revs at 1200 for example, I will get a constant 27 degree reading, so it seems the variability is all at idle.
Am I worrying about nothing? Any advice gratefully received.
Since reverting the map, I still get occasional misfires shown on the Autel, but they have not generated a latched error code. They are listed under On-board Mon Test; Mis-fire Cyl 1-4 Data; Misfire counts Last. I will get a few registered on any drive, but no particular cylinder is worse than another. e.g. short drive of 3 or 4 miles = 1 or 2 misfires shown for each cylinder. I think these are real, as I occasionally feel the car stutter on pick-up. These errors never latch and are reset when stopping the engine. On a long drive - 90+ mins - I might get 5 misfires per cylinder. (BTW - there are historical latched misfire values shown under EWMA Misfire Count (1 or 2) and these don't get reset on switching off the engine. I wonder if there is an easy way to reset those values?)
The other thing that I've noticed is the advance timing fluctuates a lot on idle. Under: Live Data; SparkADV degrees, on idle (e.g. 800rpm, no throttle) I will see fluctuating values from 9 to 21 degrees. If I apply a small amount of throttle to hold the revs at 1200 for example, I will get a constant 27 degree reading, so it seems the variability is all at idle.
Am I worrying about nothing? Any advice gratefully received.