Intermittent sudden power loss on 2001 1.9 TDI Golf

JohnCC · Post by **JohnCC** » Mon Oct 04, 2004 8:14 am

Hi-

Driving home last night in really awful weather on a freeway - rain, wind, spray, the works - the car started to lose power intermittently.

It kind of feels like my old TD did just before the turbo seized, although I hope that isn't going to happen on this one as it has a FVWSH, so should have had regular oil changes and only has about 100,000 miles.

It became more frequent until it was pretty much constant. The car struggles to rev above 2500 -3000 rpm under load, and feel sluggish and restricted. Occasionally you feel the power stutter back in for a moment, but it's rare.

It may be coincidence, but what could cause this that is water related? I wondered about the paper air filter becoming sodden - but some searches talked about failing air mass sensors - could this be aggravated by water?

Other stuff I suppose is a loose hose - does this one have a hose from the manifold to fuel pump like my TD did to increase fuel under boost?

Also, I guess it could be a wastegate problem. On my TD, loss of boost was caused by an EGR solenoid getting stuck open - does the TDI have the same?

What else should I look for?

I have a boost gauge I could try - what pressure should I be seeing?

Thanks!

MayorDJQ · Post by **MayorDJQ** » Mon Oct 04, 2004 11:59 am

It sounds like classic MAF failure.

The easiest check it to unplug the MAF and drive around. If there seems to be more power, the MAF is dead, or dying. If there's no noticable difference, try to find someone with VAG-COM software in your area, have them plug in and do a road test.

It's not too likely that the airfilter is getting wet, but I suppose it's possible. That's pretty easy to check.

Another problem could be a clogged intake manifold, which can be checked by carefully removing the EGR valve and looking into the manifold. If it is clogged it should be removed and cleaned out, but this is pretty labor intensive, so check the MAF first.

The TDI doesn't have a traditional wastegate, it uses a "Variable Nozzle Turbine", meaning the vanes on the exhaust side of the turbo open and close at the instruction of the ECU to control boost. The turbo has a vacuum canister underneath it that actuates the vanes on the turbine. There's a rod coming out of it that can sometimes get a little sticky either. If you have a Bently repair manual, there should be a picture in there of it.

Try the easy stuff first.

JohnCC · Post by **JohnCC** » Mon Oct 04, 2004 6:05 pm

Thanks! I unplugged the MAF sensor, and it didn't exactly go faster - maybe a bit, not sure - but it got rid of the intermittent power surges. Hard to say if that's a positive ID or not.

If I know a place with the software though, they can check this for definite, right?

MayorDJQ · Post by **MayorDJQ** » Mon Oct 04, 2004 10:29 pm

Assuming the person is moderately experienced with VAG-COM, he/she should know how to do the MAF check. It involves going into the engine module and making a few runs in 2nd or 3rd gear from 2000 RPM up to and past 3000 RPM. The readings should be within a specified range. The FAQ's on tdiclub.com explain it pretty well.

madmax · Post by **madmax** » Wed Nov 23, 2005 5:29 pm

Hi something you may want to look at is your car may have a screen in the air intake this is before the main air filter my 02 jetta had one it is at the very beginning of the air intake system in side of the duck work to the air box remove the air box and the duck work to the front of the car if your car has one of these screens remove it it is so fine and a small area that it can get plugged up with very little dirt the main air filter will keep all the dirt out of your Eng. only some of the VW models have these screens
they don't seem to be very important