Desperate: A4 TDI Struggles in Wet

[n30_mkii]

I have had my Audi A4 (b6) TDI for around 3 years, I got it when it had 100,000 miles on it. It has always had issues when wet, and seems to be getting more often and worse.

What happens is, I have to give it lots of revs to even pull off, when I dab the accelerator the car does not accelerate until a few seconds later, at which point it throws out lots of black smoke. It seems to do it only when there is spray arround or we have had a lot of rain.

I have taken it to my local garage before when it's done it. They have taken the air filter out which seems to get a little wet (is this normal? there is nothing inbetweent the front grills and air filter to stop water going through)

They asked me to try it without and it made no difference. Last time it was in they replaced the MAF and the fuel filter, and then it seemed ok for a while, but it still occurs. It's really bad going up hills as the sudden lack of power and delay on the acceleration makes it a nightmare.

I'm really scratching my head with this, and any garage I have ever mentioned it too has said they have never heard of this sort of issue before.

I could really do with some help if someone would be kind enough http://forums.tdiclub.com/images/smilies/confused.gif

[willster]

what engine is it?

[n30_mkii]

1.9tdi 130 pd (awx)

[neilmassam]

I'm experiencing the same problem 2002 Audi A4 1.9 TDI (100 BHP), following a car wash or heavy rain my acceleration lags very briefly and picks up again shortly after (very frustrating and also dangerous).

The engine runs like a dream under normal weather conditions and is very responsive even after the initial accelaertion lag in the wet so I don't think it's anything too serious. I'm convinced though that this is an engine electronic/ motronic problem coming into contact with water somehow/ where.

I recently had a brake system design fault fixed by Audi which was causing water to collect in the bulkhead chamber below the windscreen (which fatally damaged the brake servo, pump and pipes). Apparently the engine electronics box is located in the passenger footwell area (which is below this problem area) and I have had water appear in this area for no apparent reason. I may be wrong about this but I'm going to get it checked out as soon as I get the chance.

I've seen lots of posts where MAF filters have been replaced etc. but with no positive results so I'm trying to avoid doing this unless it turns out to be this thats causing the problem.

If you or any other forum members find out anything or know what could be causing this then I'd be very grateful to hear from you.

[elPaulio]

If replacing the AMM (MAF) made it better for a while then I would suggest you check the wiring to the AMM and see if there is any way that water can get into it.

It sounds very much like a water ingress/wiring issue.

Paul :biglaugh:

[willster]

i had the plenum chamber re-call work done to , water was coming into my passenger footwell. i dont think the ecu is located there,just the central convenience module that controls windows,lights etc. so i wouldnt have thought the water ingress there would affect power delivery.I would use a good quality injector cleaning treatment in your fuel ,put some specialist electrical insulating compound in your maf connector end(Dow Corning DC4 ) some are prone to getting damp /corroded and give weak ,mixed signals to the ecu which in turn affects fueling and ultimately power. These are both cheap easy jobs you can do yourself and may work,so youve got nothing to lose.

[nutter1980]

I agree with wilster as I have had the exact same problem. I actualy ended up replacing the electrical connector to the maf sesnor. After replacing it I used some electrical switch cleaner on the connector aloud it to dry and then applied Dowcorning 4 to female side of the connector.

No problems since.

Dowcorning 4 is available from cpc.farnell.com

[n30_mkii]

Just an update:

It was doing it again this morning, so I took the opportunity to pull over unplug the MAF connector and then startup and try for a couple of miles. The car seemed to be smoother, but there was a severe lack of power, and no turbo boost at all, so it had no acceleration like normal.

I then re-connected up the MAF, back to how it was first thing, no power for a few seconds when engaging the accelerator then all of a sudden lots of boost then black smoke. Did it for a good 20 miles this morning. Got back to the car at 4pm this afternoon, ran fine. I pulled over again to see what effect the MAF would have if I unplugged it. Just the same as when I unplugged it when there was the issue.

It was fairly smooth but no turbo seemed to kick in and hardly any acceleration.

So it seems that the MAF is making a difference when plugged in. If it isn't the car just crawls without the feel of any sort of turbo boost at all.

There does seem to be some wet damp area down the front right hand side (looking toward the car) where there is the plastic missing as mentioned.

So I think the MAF is ruled out. i dont get a build up of water on the passenger side that I know of. Someone mentioned a snow snorkle but I dont think mine has one.

Can anyone tell me if the intake for air, from the front grills to the air filter should have any kind of blocking material to stop spray and leaves going straight down to the filter?

[Turbokiisseli]

Some of the previous B5 models had a snow screen in front of the intake tube behind the grille. I haven't seen them in B6s though.

The ECU is located in the same area as the battery. On RHD vehicles it's in front of the driver.

You problem could also be related to the pressure sensor MAP. Check the connector.

[n30_mkii]

The ECU area seemed to be bone dry, but where is the pressure sensor map?

[agdaubern68]

Thanks You for your advice it helped me allot I think my problem is the MAF It just loose power wile I am driving. I am staying in South Africa and we do not have a lot of rain here so the car cannot use the excuse of rainy weather.

[teaspoon]

Fear not people..

I have had exactly the same problems on my A4 B6. Each time I drove into a car wash, or each time there was heavy rain, she lost all power. It all came to a head on Sunday when I got stranded on the motorway and had to be towed home (over 240 miles).

I took it into the garage the following day. I'm happy to say they sorted it out!!!

The problem (simple enough!) was this:

There is a channel under the windscreen wipers where water is supposed to run into and through a couple of drainage holes. Now with mine, the drainage holes and the channel were blocked. So water was filling up in the channel and overflowing into the electrics and fuse box, causing a short circuit. They cleared up the blockages and she was right as rain. I even drove through a car wash with no ill effects.

its simple enough - certainly worth a try.

[n30_mkii]

I think we may have got to the problem. I have just poured some water down the window screen using a watering can. The Water is leaving through the side drain holes, but quite a lot is entering the firewall / battery area and pooling, afer half a watering can there was nearly and inch or so. It looks like the drains are blocked. I have managed to get my hand under the battery area and shift a gromet type cover to drain the water for now. I will need to get the battery out and clear the drain holes under there.

one under the battery? and one further left near the ecu area?

Thanks.

Fingers crossed we have nearly got to the bottom of this!

[kurtas2006]

I take it this is a known problem.

Was the plenum chamber recall for all B6 or restricted to certain models/chassis numbers ?

[n30_mkii]

Don't think mine ever had that recall. plenum chamber being the battery area? Drainage issue?

[missmellyuk]

My 2004 car was having this problem, thought it was fixed as car has been great since filter change and having a friend thrash it for a week.

Anyway washed my car last weekend, it also rained her and she lost power again, but one a quick gear change down and flooring her fixed and she was rough for a few days. Now a few dry days later and she hasn't done it, I hope this is my problem.

I take it I open the bonnet and tip water down the windscreen and see where it goes? And if it runs into the engine area, this is my problem? No?

Sorry but I am female, then what do I do to fix it?

Thanks

[white.akita]

my 2001 a4 tdi had the same problem it was also water gathering around the battery compartment, a very common problem.

[Turbokiisseli]

It's a campaign fix for Audi to clear the water drainage holes. 51B7 is the code, as I recall.

[kurtas2006]

It's a campaign fix for Audi to clear the water drainage holes. 51B7 is the code, as I recall.

How does a campaign fix differ from a proper recall ? or is it the same thing ?

If I say to the local dealer I want 51B7 campaign fix can I get it done free ? The service was done a few months ago and I don't fancy waiting a year to get it done if it is a freebie.

[white.akita]

if it has fash then it should of been checked and corrected if blocked.

[Turbokiisseli]

I believe campaign fixes are only something that are done when you take your car for regular maintenance, so they're not recalls. Mine had 51B7 done when I took my car for a cam belt change at the dealer a few weeks back.