Passat 2.5 v6 TDI occasional loss of power.

[jasear]

Hi,

I have noticed ocassionally when I put my foot on the accelerator the car accelerates rapidly until it reaches around 60 mph (in 3rd gear) and just goes flat. This only happens very occasionally and on most occasions it is perfectly fine. The car does feel a bit lumpy in first gear when moving from a stationary position but I am not sure whether this is just normal with the 2.5 TDI engines.

If I accelerate normally I never encounter this problem. It only seems to happen when I put my foot down on the accelerator. Once it reaches the flat spot it doesnt matter how much I press the accelerator nothing happens. However it is ok after a while (a few seconds later) and accelerates normally (without having to switch off and restarting the engine).

The car is 99 V reg and has only done 50,000 miles (possibly a lot of town driving and clogged up pipes?). I have read through a lot of forums and searched here and the most common diagnosis seems to be to change the MAF. However most of the threads I found were relating to the 1.9 Tdi model I am not sure whether the same would apply to the 2.5 tdi.

Therefore I would be grateful for any help.

[jasear]

help!!!

[CherryB]

I have had the same symptoms as you altho mine has done 165k. I tried a new boost control sensor/solonoid with no change. The filter for the crankcase pressure was changed as there was a pressure build up within the engine and this helped a little, but the flat spot was still there.
I then looked in the air box and saw that it was quite dirty, so cleaned it out (wth air meter removed) and then cleaned the mass meter with brake and clutch cleaner ( only a few squirts ) and let it dry naturally.

What a transformation..... It really shifted after that. and the flat spot gone. I feel that a new meter is really needed, but it still seems to go well and returns 40+ mpg. :biglaugh:

[mr-mixalot]

:biglaugh:

Hi jaesar, had exactly problem as you, posted but never got a definitive answer so thanks for the tip CherryB

Will try cleaning the airbox and let you know what happens

CherryB, what was your MPG before you cleaned?

Thanks

[CherryB]

Hello Mr Mixalot, the mpg hasn't really changed. I suppose i get one or two mpg better, but now that it goes so much better, i can enjoy spirited drives.
If I cruise to work, over 25 miles, with climate on, I average about 42-44. If I give it some gas, it hovers around 38. There is less need to to hold on to the gears though, as that annoying flat spot at around 3000 rpm has gone and there is more low down oomph.
Hope this helps. :D

[rob1976]

Hello cherryB i seem to be having the same probs as you i have covered the same millage and changed many parts, nice upto 3400rpm then flat doesnt want to pull any more i think it could be a faulty maf but i did change this back in september i might try and give it a clean with clutch and brake cleaner spray is yours pulling still pulling well after the clean?