Problems starting a Mercedes E280?

The engine turns over but won't start and if it does start, then the revs hang up at 500rpm. Using the throttle the engine accelerates to about 1200rpm then cuts back to 800rpm. When the engine is warm everything seems to work as normal. When cold the above usually happens. Any ideas?

Asked on 16 November 2015 by Alison Conway

Answered by Alan Ross
Although you do not mention the year of the car,it would appear that one of the many sensors fitted has a fault. The most likely one is the ECT ( engine coolant temp sensor), however there could be quite a few other sensors that would result in similar fault.
They are:
MAF (mass air flow)
MAP (manifold absolute pressure)
IAT (intake air temp)
CKP (crankshaft position).
Therefore rather that changing one and hoping, you should have a diagnostic check carried out, as this will then show a fault code/s (they will be P ---- 4 numbers). From this code we can identify which sensor is the problem.
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