CDTi Stalling under heavy acceleration

[FROGGY]

Originally Posted by pondweed

but surely if it runs fine with the Synergy turned off...? Why would the leakback be tuning box-specific?

It isn't, but the extra demand placed on the fuel system can be enough to cause the cut-off.

Another symptom of leakback is poor hot starting, leave the car for 5 minutes, come back and no go. Wait 1/2 hour, no problems.

I can only state what happened in my case. Ron sent me another box, still cutting off. New in-tank and under-bonnet pumps made no difference. Did the leakback test, one injector very bad. Had them rebuilt and balanced and the car runs like a dream.

Mick

[Roverron]

Originally Posted by pondweed

but surely if it runs fine with the Synergy turned off...? Why would the leakback be tuning box-specific?

Its possibly one of the electric pumps.
The cutting out is caused by inadequate fuel pressure (the ecu tries to turn up the HP pump but if, once its on max and the pressure is still not what it should be, the ecu stops the engine in case of fuel starvation)

With the Synergy off, the fuel requirement is a lot less so there is no fuel shortage reaching the HP pump so no cutting out.

Leakback could cause it but normally this would cause bad starting.
A faulty in jector could also cause it, but a lot of black or grey smoke would be seen.

If there is no smoke, then I'd suspect a fuel supply issue - clogged fuel filter, in tank or underbonnet pump issue or possibly a faulty HP regulator.
(this tends to cause starting problems as well)

Ron

[Phil_B]

Thanks Ron (and others) for the advice.

The car is under warranty so I think I'll remove the Synergy and take it to a local x-part centre with the fuelling problems. See what they come up with.

In the meantime is it easy to check any of the items listed (not the leakback, that's out of my mechanical scope I'm afraid)?

I'll let you all know how it goes.

Cheers

[Phil_B]

It's at Luffield as we speak and they are replacing Injector number 4 (ouch!).

Will advise if this has sorted the problem once I get my mits back on it.

Cheers

[Phil_B]

Well, got it back and all is well with the world again Switched the Synergy back on and no problems at all now...happy days.

Wonder if the MPG will improve now?

Thanks again for all the help and advice.

[FROGGY]

Injectors strike again, eh?

Repeating one of my comments some time ago, I think the leakback test should be one of the first things to carry out for cdti cutting off problems.
I am no diesel expert (getting there though!), but wonder if the standard swapping of fuel pumps for this type of problem could end up as a temporary cure, the uprated output masking injectors failing?
Just a thought.

Mick

[Phil_B]

Well, after 3 months of Happy MG'ing the car is back at Luffield haveing the other 3 injectors replaced

Car cut out on the approach to a roundabout yesterday and just would not start again. AA came and ran some tests and determined that there was plenty of pressure at the fuel filter (so unlikely to be a pump problem) but hardly any at the rail. Off it went to luffield who did a leakback said that the only good injector was no.4 funny that eh?

anyway, they are replacing it now and i will soon be £800 lighter for it, great! Also need 2 new tyres and the cooling fan motor is kaput, only comes on at hovercraft speed, nothing before. Garage has quoted £600 to replace this, is it worth trying to do this myself as I am reasonably handy with a spanner, but far from being a trained mechanic.

[Jules]

Sorry to hear that Phil. Hope you get the injectors sorted reasonably.
For future reference for you & other owners, my price for new Cooling Fan Motor (fitted) is £450.
Even Londoners take the day off to pay me a visit. Garages down there are quoting in excess of £750!
Furthest travelled owner to Sunny North Wales so far, for me to carry out front end jobs was a chap from Aberdeen!
Hope this helps: http://www.the75andztclub.co.uk/foru...ad.php?t=24506

[tony_fry]

I have a problem with my car cutting out after a run, it start idling very bad, (between 5000 and 8000 rpm on the speedo) and if I take it out of gear (Automatic) and then put it reverse the engine cuts out, but then straight away. This does not happen all the time.

Can any point me in the right direct on the "How To" do a leak test, I have done a search and there's bit and pieces on a few threads, but not a complete guide.

Many Thanks
Tony

[JohnDotCom]

Genuine OEM Injectors from XPart Parts Dept's or Rimmers are
Part No: MKG100270 Kit-injector-fuel multi point injection Quantity 4 £160.65 + VAT each

Might be cheaper from BMW outlets.

Tony I think your tickover is about 4250RPM to 7400RPM to fast.