Hi

Have a problem with my 2011 Grand CMax 1.6 Ti Petrol . When I have to stop at a junction and the revs drop with the clutch down, about 10% of the time the revs will drop very low and then the car will cut out. This has started happening more and more recently and it seems to be becoming more difficult to start after this occurs, with the starter motor turning over for longer in order to get the engine fired up again.

If i get a normal idle, the car will sit there without problem and generally it runs well with no issues when in gear.

One thing of note, if you blip the throttle, there is a short whooshing sound which to me indicates a problem with vacuum hose, maybe PCV.

There are no codes coming up on forscan that obviously point to this. Maf sensor values seem ok and other visual checks seem fine. Are there any real-time tests i can run to make 100% sure that this is the problem. I cant actually locate the hose to check it, think it's between the manifold and engine block somewhere but guides on the 2011 cmax seem few and far between online.

Any suggestions would be very welcome.

Thanks

Mark

Crankshaft position sensor, possibly starting to fail ???

23 hours ago, unofix said:

Crankshaft position sensor, possibly starting to fail ???

Would this give an OBD error code?

Only sometimes. If the position was slightly wrong OR the pulse was sometimes week then it would probably not cause DTC.

With those symptoms and no codes I would have a go at cleaning out the Throttle Body.

There should be plenty of info on how to do it if you Google it. 

It may need to be relearned afterwards.