Passat 2.0tdi dsg 170 2007 misfires over 3000rpm

[scanny]

Can anyone help my Passat 2.0tdi dsg170 misfires over 3000 rpm the car drives great around town and doesn't miss a beat ,it only happens when I accelerate over the 3000rpm .ive checked the codes and nothing comes up any ideas thanks

[zollaf]

what did you use to check the codes ?

[scanny]

Used a Mac tool obd2 reader ,replaced fuel filter cleaned maf sensor still the same

[zollaf]

scan it with a proper computer not just an obd reader. vcds is the best for this. was there any black oil in the fuel filter ?

[scanny]

It's was dirty and yea black but don't think it was oil ?

[zollaf]

what else could it be then if its not oil. common fault, tandem pump leaks oil into the fuel, turns fuel black, as evidenced when you change the filter. fit new tandem pump. problem solved.

[scanny]

Appreciate your help but what in the tandem pump also is it hard to replace thanks

[zollaf]

combined fuel / vacuum pump on back of engine. not hard to change

[scanny]

Ok thanks you said its at the back of the engine but is it on the side of the cylinder head cheers

[zollaf]

yes, on the back of the head, or above the gearbox.. depending on which way round the engine is. disconnect the fuel pipes and vac pipe, 2 bolts and its off. make sure the new one lines up with the camshaft and dont force it on.

[scanny]

Again thanks for your help suppose you don't know much about BMW X3 2.0d the wife's motor

[zollaf]

whats up with it ?

[scanny]

It's the 2006 m47 diesel ,if you leave it over night then go to start it in the morning it will stall,but then turn it over and it will run fine the rest of the day ,had the glow plugs changed last year same as the Dpf filter and new inlet manifold ,don't now whether it's a fuel pump issue or something electronically also replaced dme relay still the same

[zollaf]

sounds like a fuel problem, draining back to the tank and airlocking. fuel filter connections would be a likely culprit. if there are any clear fuel pipes check for air bubbles.

[scanny]

Ok cheers I'll look into that

[scanny]

With the tandem leaking oil into the fuel would it do the opposite diesel into the oil just thinking if I would need to replace the oil thanks

[zollaf]

probably not a bad idea.

[scanny]

Started to remove the air filter box to get to the tandem pump but there's a brake hose attached can't see how it disconnects any ideas thanks

[scanny]

Someone suggested it could be the injector seals causing oil in the diesel filter

[zollaf]

the tandem pump pressurises the injector rail to 100 psi, the engine oil runs at about 70, so a leaking injector seal will put diesel into the oil. the tandem pump is fed by the intank pump which is only low pressure, and its on the low pressure side of the tandem pump that oil finds its way into the fuel.

[scanny]

Ok I understand you , does the brake booster hose come off easy from the pump thanks

[zollaf]

should just pull off. i think its a rubber bung with plastic over the top, you might need to squeeze the plastic outer , like a child proof cap, but it should just pull off.

[scanny]

Replaced the tandem pump just can't get the car to start followed the instructions by getting the fuel back to the filter just can't get it going is there anywhere where I can bleed the air out

[maf]

I had a misfire as you described
Cattaclean sorted it ,added to a 3rd of a tank of diesel,drove it in sports mode until empty now perfect !!

[scanny]

Thanks Zollaf car runs great again x3 next to sort out cheers

[scanny]

Just took it for a blast drives mint ,massive difference in the brakes to cheers