2008 2.0SDI Caddy. Cutting out if left ticking over

[sandymuir6003]

Evening all Caddy fans

Help needed. Have a 2008 2.0 SDI Caddy for last 5 years. Over last 2 years it has developed an issue where it will cut out if left ticking over for an extended period of time, or if left off load during driving (as long as revs are above tick over its ok). If it cuts out it takes forever just cranking over to get restarted, which can be troublesome if cut out at traffic lights. Local garage diagnostics shows over-fueling to cylinder 4 and possibly 3.

No other fault codes showing on home diagnostics or garage equipment

Anyone have similar problems and all help appreciated. Have trawled through forum with limited success.

Caddy is called Vinny and has 108k on clock. Transport for 2 pampered Labradors.

Sandy

[BenT]

Hi there.

So... a few questions at this point!

1) How long roughly of idling does it take before it cuts out, typically?
2) After you've cranked it for a while and it eventually fires up, does it instantly run perfectly as though nothing had ever happened, or does it gradually cough to life and stutter for a bit, probably with some white smoke?

That might help to narrow it down a bit. Thanks!

[sandymuir6003]

Hi Ben,

Thanks for reply, to answer first part will tick over for anything between 5 and 15 minutes then cut out whilst standing still in traffic. If it cuts out during driving it is usually if i'm pulled up at lights/stuck in traffic. you can usually hear a change in the engine tone as if its starting to struggle so at that time add a bit of throttle and its right as reign.

When it eventually starts, no smoke beyond a puff on startup (pretty much same as starting from cold) and runs as normal

Finally, has just recently happened for second time about a week ago, it cuts out at slow speeds. First time i thought i had stalled it but second time it was hard to restart the van.

Hope this helps but any further info needed just send a reply

Regards

Sandy

[BenT]

Thanks Sandy,

That's a really odd one. It sounds like more of an electrical issue to me than a mechanical one. If it was gradually coughing to life on restarts after cutting out, I'd have said that you might have air getting into the fuel system, or that maybe the in-tank lift pump had failed. But with it starting and running normally when it does eventually go, this seems less likely.

I'd start with the simple stuff first, since you have no fault codes, and change the fuel filter if you haven't already. Have a look/sniff for fuel leaks under the bonnet too, just to rule that out. Do you hear the in-tank pump hum when you first switch on the ignition?

Did the problem start after a cambelt change by any chance? I've said this a number of times, but if the cam to crank timing's out very slightly it can cause starting issues (you'd normally get a fault code though).

Otherwise, make sure you check the fuses and relays for signs of burning out. Failing this, it could be an ECU problem (second hand ones aren't expensive, but would need to have the immobiliser disabled or recoded to work with your van).

Sorry to give you all of these possibilities! Quite hard to diagnose from afar... good luck

[PJD]

Similar problems with a BMW years ago was one of the crank timing sensors.

Though obviously different engines, being VW and BMW, might be the same problem.

The sensor might be breaking down as the temperature of the engine increases, which is why it happens after it has warmed up.

[PJD]

Another thought and a common check is to disconnect the mass air flow sensor plug. The engine should run steady without it, albeit with poor emissions.

You could locate it, check it runs without it. Put back in place and remove when it plays up to see if that's the problem.

Always worth squirting cleaner on them when the engine starts to play up anyway. To see if that helps. So maybe worth a go first to see if that solves the problem.

[sandymuir6003]

Thanks Dan and PJD,

Am working through suggestions but weather and time is working against me.

Quick replies to suggestions, no cam belt has not been changed recently so have discounted the cam timings. Fuel filter was changed last year but will change out as it is a good easy option. Mass air flow sensor was changed due to a fault on the intake air temperature sensor and its a combined unit. Problem still there but think there may be a broken wire so will need to investigate further. Runs as normal with sensor removed from system so have discounted it as part of the running problem.

Checked fuses and relays and no sign of any burnout and all fuses have been checked with multi-meter to ensure there good.

Once again thanks for suggestions, they have give me a great starting point for where to look and will keep everyone informed.

Sandy

[Dorisan]

Did you ever find what was wrong with it?
I have an 2010 and is doing exactly the same thing as yours and can’t find what's wrong with mine
Thank you