Mercedes S550 start and stop with too short a duration, how to do


This post starts with the issue that 2007 S550 start and stop with too short a duration, what’s the problem located in? how to do? Go on reading following parts.

Car model: 2007 S550

Mercedes Benz car scanner to read code:

Star Diagnostic System (SDS) SDConnect C4


Car issue:

Will turn over and start and then immediately shut down or just whine and never catch, After trying to start the car 10 – 20 times it will start and run just fine with no warning or check engine lights. I brought the car to the dealership where they kept it for a full week and said that they couldn’t find any codes nor could they get the car to not start!!!!! WTF, I think they are playing games with me because when I got the car back home, the next morning it did it again. ”


Rereading it properly, it sounds like fuel pressure….

if it starts and runs for up to say 20 seconds its using up residual fuel pressure in the rail… the idea should be the pump comes in and the pressure (depends on each car what causes it to run) is there from the get go. Sounds like on yours its not getting signal reliably. my ramblings when I thought you kept trying to start and stop with too short a duration… Like manoeuvring the car round the drive to get another one out…

This may be part of the problem….

Any car with a CAT should not be started and turned off again straight away. As a min hold revs at 2k for at least 40 to 60 seconds before shutting it down. In fact its good practice to run a car for a min of 10 miles every time you start it… (its why Taxi’s do 500,000 miles and others need an engine at 60,000)

There is a huge risk a lot of unburnt very rich cold start fuel confuses the sensors in engine management that control fuelling / help look after the CAT. Believe it or not you can easily flood a fuel injected CAT car (my wife ‘s Pug 306 2ltr 16v and her Golf 1.6 16V BOTH did it…. doing exactly what I told her not to do see first paragraph !!!)