Originally Posted by
Padgett
First I connect a dongle ($12) and use Torque ($5) on my phone to check for reported faults. If you were reading misfires, you were doing something similar. I would have expected an erratic idle to set a count since it is reading rpm deltas but may wait for closed loop before starting.
Have to keep in mind that the elecronics in these cars are really pre-milennia and in the infancy of OBD-II. When I see something like this I run a fuel pressure check to see if in spec. If OK and the tank is under 1/4 full I check for water in the gas (both can be done at the fuel rail). Note: since they started putting ethanol in the gas, I rarely see water any more. We used to "winterize" gas by adding "gasoline anti freeze" - ethanol - to the tank).
Next I start looking at secondary ignition (ICM, coils, wires, plugs since neither fuel pressure nor water nor secondary ignition will normally set a code in early OBD cars.
Where to go from there depends on what you find. YMMV.
OR... rather than guess... He will have Mercedes' finest technicians tap into it and they can pinpoint exactly what's wrong with it.
At this point, I'm just happy to learn that it appears to be something completely unrelated to the problem that I paid to have fixed. Now that it's in the hands of Mercedes, I really can't offer much in the way of helping him find cheap parts because they will likely want to provide them. Hoping it's something simple like an unplugged connector or vacuum line.
At the end of the day, I appreciate Bruce's friendship and I want to do everything I can to keep it intact. That's why I made the trip up there last night... I never want my integrity to be called into question.