M103 Drivability Problems
I've been reading about the various problems with CIS engines. I came across this in the Mercedes-Benz E-Class Owner's Bible and wondered what the experts think about it. If this has already been discussed, I apologize in advance.
'Some M103 engines develop a slight hesitation off the line when the engine is cold. They may also cold start instantly and then die, but restart easily and then continue to run. By adjusting the fuel distributor lower chamber pressure to .45 bar instead of .4 bar, both of these symptoms tend to disappear. The car also seems much livlier off the line.
You are not really richening the mixture when you make this adjustment. Instead the adjustment is compensating for basic wear and tear and any unmeasured air leaks that have developed over the years. You need a CIS fuel pressure gauge to measure and adjust the fuel pressure. If you reset the EHA, the idle mixture should also be checked and adjusted.'