B5.5 Passat in limp mode in wet!

[Lordbenny]

Driving on M3 at 70mph at 2500rpm in pissing rain suddenly when putting my foot down I got no more power. No dash lights and TBH it felt like I had a bit too much power for limp mode. When I stopped turned off and back on again I got all my revs in nutural. Any ideas?

[Chris32345]

What engine?

[Lordbenny]

1.9 tdi 130

[Hub]

So revs didn't rise, ie not clutch slip?

[Lordbenny]

Hub said:

So revs didn't rise, ie not clutch slip?

Nope! Couldn’t go faster than 70mph. When I stopped it reved to max rpm

[Lordbenny]

Left the car for 8 hours then had to drive home in similar rainy weather. The car was fine until it did it again after half an hour on the motorway. When I got off the motorway I pulled over switched the ignition off and back on again and the car was fine! There where no warning lights at all. Could this be the MAF sensor?

[Belle427]

Hard faults to pin down but if it were my car I’d clean the egr valve first and get that out of the way.

[E-bmw]

Lordbenny said:

Left the car for 8 hours then had to drive home in similar rainy weather. The car was fine until it did it again after half an hour on the motorway. When I got off the motorway I pulled over switched the ignition off and back on again and the car was fine! There where no warning lights at all. Could this be the MAF sensor?

Can't say for sure, but the one time I had a dodgy MAF before it was like "hitting a brick wall" and the car would only tick over until it was reset.

[Peanut Gallery]

Blocked fuel line / filter? - revving in neutral uses less fuel than going doing the motorway at many leptons? - A hard pull up a hill would soon tell if this was the issue?

(I have found this on older petrol engines, I do not know if a diesel will behave the same way)

[bern]

Had something similar with my non-PD Passat TDI. The variable vane turbo was gunked up with carbon sludge. It was stuck in the high boost position so when it needed low boost the engine saw it was producing high boost and put it into a limp / safe mode, no warning lights. Can't remember if vag-com showed anything.

I cured this by removing the exhaust from the back of the turbo and squirting Mr mussle oven cleaner into the hot side of the turbo and moving the vane actuator rod up and down manually, every 15 minutes for an hour or so. Worked a treat, this was at least a year ago and it's still fine now. Plenty of vids on YouTube showing it being done.

[bern]

The correct way would be to remove the turbo and split it. Then clean the variable vane part properly.

But 20 year old Passat and all that!