1.9 TDI loss of power in the wet

[elliottj]

Hi all

First of all apologies if this has been covered elsewhere (couldn't find a thread).

My A4 1.9 TDI has a habit of acting strangely in the wet. When it is raining/roads are still wet the car loses power and begins to splutter, almost mis-firing. Once the car has dried out the problem stops and the car returns to normal.

Anyone any ideas what the problem could be?

Thanks in advance.

[Camb-Tech]

I would start by checking the chamber where the fan and battery sits for blockages and check the passangers foot well for dampness (remove the passanger before hand).

Take the engine cover off and do a general check on any electrical connectors you can see.

Use or find someone with a ODB code scanner like VAGCOM and do a diagnostic check.
If any sensors are being grounded / shorted by the water this should be logged.

Check the alternator connections too.

[elliottj]

I would start by checking the chamber where the fan and battery sits for blockages and check the passangers foot well for dampness (remove the passanger before hand).

Take the engine cover off and do a general check on any electrical connectors you can see.

Use or find someone with a ODB code scanner like VAGCOM and do a diagnostic check.
If any sensors are being grounded / shorted by the water this should be logged.

Check the alternator connections too.

Thanks for the suggestions. I'll try all of the above.

[kenney]

Check the air filter housing for water ingress

[nutter1980]

I had the same problem, I had a cracked maf sensor connector, I used some switch cleaner and some dielectric greese " dow corning4 " to prevent moisture ingress on the connector, Problem has never come back ever since.

Hope this helps, It does sound like the same problem.

[toff]

I suspect it will be something to do with the electronic measurement of air (as nutter suggests - the MAF).

It won't be ignition related and I doubt it'll be fuel related (unless the electronics for the fuel delivery system are getting wet - but more likely to be air related).

One other possibility... the 1.9 is a little underpowered for Quattro in my honest opinion and the engine does bog-down when driving all 4 wheels! (maybe I've been spoilt by previous cars!) Is yours a Quattro?

Al.

[Buzzoff]

I would give all the electrical connectors a check over like the MAF sensor, good advice to check the ecu tray too, but take care I think you need to remove the wiper arm to get in on all of the lid fixings.

I understand the wiper arms go brittle after time and can snap off, it happened to a friend, try a bit of wd40 the day before on the splined shaft to help free it up.

good luck

Cheers

[elliottj]

I had the same problem, I had a cracked maf sensor connector, I used some switch cleaner and some dielectric greese " dow corning4 " to prevent moisture ingress on the connector, Problem has never come back ever since.

Hope this helps, It does sound like the same problem.

Thanks for your reply.

As i am very much the amateur mechanic i have a few questions.

Did you remove the sensor then clean and seal it? or did you leave it on the car?
How much grease did you put on it? (ie. did you cover it in the stuff?)
Can i do any damage if i screw this up???

[nutter1980]

Thanks for your reply.

As i am very much the amateur mechanic i have a few questions.

Did you remove the sensor then clean and seal it? or did you leave it on the car?
How much grease did you put on it? (ie. did you cover it in the stuff?)
Can i do any damage if i screw this up???

Hi, It so easy, I am not a mechanic.

To solve my problem I simply unplugged the cable connected to the maf sensor sprayed in some switch cleaner, reconnected and disconnected afew times.
That cured my problem. I added the dielectric grease afew weeks later, you dont have to use it, it just ensures good electrical contact and keeps away moisture.

Ohhh and dont use silcon seal !! Do not use Silicon seal !! Do not glue the connector into the socket...

[ninotschka]

\mine had the same problem about a year ago. It turned out to be the air mass meter , cost me around £70 to have it fixed by an Audi Specialist (not a dealer)

Good luck!