MK7 Jumbo , rough idle, engine shaking for 1st 10 minutes

[tcsheffield]

Hi all, I have recently (November 17) had the prv/scv replaced, pump learn etc. The van was fine until a few weeks ago. The horrendous shaking, hunting returned. This happens until the van has been running for around 10 minutes, then its fine for the rest of the day! I returned to the diesel specialist who did the work in November. They thought it could be a faulty valve or may be EGR. Plugged it up, no fault codes, fuel pressures all fine.

I'm tempted to take it back again, but if their computer doesn't show any faults or fuel pressures out, they seem to be at a loss.

Has anyone had similar?

Just to confirm it only does it for about the first 10 minutes after start up.

Many thanks in advance.

Tom.

[knobby1]

Has the fuel filter been changed recently..??

You may have a small air leak on the fuel inlet side which allows air in and the fuel slowly drains back to tank when standing for a while and it slowly clears after several minutes...until you park it up and it all happens again. Injector leak-back lines and their "O"rings and fuel pump/tank "return" lines to and from the filter head are common air leak points....even the filter head itself is known to crack and let air into the system.

Lord Knobrot

[tcsheffield]

Hi Lord Knobrot, many thanks for your reply.

Yes, fuel filter was done in January, along with everything else on service.

If there is a small leak, could you advise how to find it ?

Is this something I could do (bearing in mind I'm not mechanically minded) or take it to my mechanic to have a look at ?

Thanks again.

[knobby1]

Hi Lord Knobrot, many thanks for your reply.

Yes, fuel filter was done in January, along with everything else on service.

If there is a small leak, could you advise how to find it ?

Is this something I could do (bearing in mind I'm not mechanically minded) or take it to my mechanic to have a look at ?

Thanks again.

Was it a "Genuine Ford Filter" or a good quality filter..?? Some cheaper aftermarket ones don't seal in the housing the best and air can leak in...

I'm not saying an air leak "is" your issue, but it may be..It's hard to determine really as the pipes are black...the best you can do is check all the injector leakback hose/pipe connections and "O" rings, the "quick-disconnect" pipes/hoses on the filter head also have "O"rings which may be leaking etc...some of them are fuel suction lines to/from the tank and air getting in will cause grief.

The filter head itself can crack letting air in....hard or impossible to see though..!

Lord Knobrot

[tcsheffield]

Hi, yes genuine Ford filter, I always use genuine parts if possible.

I think firstly check the fuel filter, ensure its not damaged, then pipes.

Thinking about it, the problem seemed to start not long after the service was done.

Thanks again for the info..

Will keep you posted, let you know the outcome.

[knobby1]

Thinking about it, the problem seemed to start not long after the service was done.

Thanks again for the info..Will keep you posted, let you know the outcome.

If this is the case, it might just be a poorly fitted filter or the filter seal is not well...can't hurt to check anyway.

Lord Knobrot