Good day. I have a South-African spec W203 C270CDI Automatic with the following issues:
1. Sporadic limp mode: Every so often the car goes into limp mode when going up a hill. Sometimes just after stopping and starting and driving off then going up a hill it will go into limp mode. When one stops, and restarts, it is fine doesn't return. Some days one drives up the same hill again and it is fine.
I plugged in Carly which to say the least is struggling to connect, but I managed to check a few values. I cannot check the fuel pressures with this tool or the fuel trims. However I manage to monitor the MAP sensor values, but not sure how to interpret them or no what a known good sensor value would or should be. Before startup the value is 14.4PSI / 101 Kpa which is atmospheric which seems to be correct. However some forums says that while driving the pressure should go to ideal of 0 kpa. Others say if you rev the engine and let go of the gas pedal it should go up and then immediately go down and then settle again to 14.4PSi. On mine however it goes up and down to atmospheric. It went down to about 96 Kpa when de accelerating. We did clean the sensor, but the values doesn't change. So can somebody perhaps inform me what the proper values should be and if this can at times cause limp mode. The outside temperature sensor reads 85 celsius which obviously is indicating a faulty sensor, but not sure if this can cause it in combination with other things. We did replace the PCV valve as this was totally shot. With Carly I did also see that the thermostat stays "cold" never go above 60 celsius which I figured out is a faulty thermostat and needs replacing so not sure if that is also having an issue. Cats are also fine and open.

2. Starting issue: When the car is cold it starts fine and quick. But when hot and standing for a bit, it can take up to 20 or so seconds to start; after it starts and you switch off the car and try again it start instantly, but let it stand for a while and try again then it struggles. It almost seems as if it looses pressure. Someone checked the codes and they said it was the control unit for the glow plugs, but when hot surely this doesn't have an issue. I did check another video on youtube and this guy said that it can be the low pressure fuel pump that takes in air as it has an oring at the back that can go bad, but it doesn't leak any fuel. He replaced his and it fixed the issue. Some others said it might be the fuel pimp in the tank, but I believe not all these cars has the pump in tank setup; hence the low pressure pump next to the high pressure pump mounted to the front of the engine.

Any ideas I can use and test perhaps without throwing the parts canon at the car which is what many shops will do.... :-).

The car doesn't have an engine light that goes on and it pulls just fine, drives fine, no hiccups on that front. Gearbox is as smooth as butter, did a gearbox service. So for a almost 20 year old car it drives almost perfectly. The car has low mileage of about 245000km