Help! Audi A4 transmission problems when it rains

[Sunflower]

Hi,

I am really hoping that someone can help on this forum. I have a 2002 Audi A4 TDi 130BHP. I have found an old thread on this site where some one describes the same, frusutrating problem. Audi cannot fault the car - well so their diagnostics tell them and so far I have had the following done to my car but while transmission has improved somewhat the fault is still there, EGR value cleaned, new MAF fitted, thermostat fitted, N75 valve fitted, crank shaft seal fitted. I only ever get this problem when it rains so I assume that it is damp related.

Symptoms:

1.When under load i.e 2nd/3rd gear using torque to pull away it hesitates... in that the turbo is not present for about 2-5 seconds and can spool up. Essentially there is no acceleration for about 2-5 seconds until the boost kicks in. Once at speed it is fine but as soon as you change gear you have to wait for the acceleration again.
2. When you turn the engine off the car shakes. This is as if the timing is out, like the engine cylinders are not stopping in correct time.
3. It only ever does this in the rain, the rest of the time it drives like a dream but in the rain it is dangerous to drive, I have to sit at roundabouts waiting for a gap the size of the M25 as I have to allow for the acceleration delay and not place my two kids in any danger
4. Large amounts of black smoke pour out of the exhaust when it is playing up. Its as if you put your foot to the floor to make sure you get away on a roundabout and it leaves the car behind a thick black smoke.

Can anyone advise on what they think the cause of the problem might be? Electrical or mechanical? No one seems to know what the problem is but I do at least know that I am not the only one with this problem. After 2 years of the problem getting worse, I am desperate for some help! I am not a mechanic unfortunately and my knowledge of engines is limited - sorry

Many thanks,

Pascale

 

[Ian-83]

Black smoke is usually a sign of over fuelling. As for the shuddering when you turn it off there is a flap on the intake which should close as you turn the engine off if it's stuck open it causes the shuddering.

 

[kite]

Check around the throttle pedal for damp /wet.
I wonder if your ECU box seal is leaking onto the throttle

 

[quattro tony]

I would def look at the flap near the egr valve,this is there to ensure the engine shuts down nicely and the above post is a good place to look esp as the ecu and various electrical plugs are in there and if its raining the water might be getting through the seal, also check the plenum drains for blockages, pretty common.Sounds like damp/ electrical issue you have.

 

[Sunflower]

Thanks all for your posts.Much appreciated and I will start looking in the areas suggested.

Just one thing that I forgot to mention about this problem. It can last for a good couple of days once it faults, like whatever the problem it is not drying out. For example, I have taken the car to my Mum's which is a good 2 hour motorway drive and it faults everytime I put my foot on the throttle. Then I will get there and leave the car to stand for half an hour and then it sorts itself out. Or like in the past couple of days, over short drives it is consistently bad but I suspect that as it was slightly better this morning, it will be ok later on today. It has never in my experience fixed itself during transmission. Bizarre behaviour!!

Would you expect to see any of the above faults fixing themselves in a hurry or are they still valid problem hunting grounds? I suspect the answer is yes but I thought that I would ask

Many thanks Pascale

 

[666markyboy]

I'll put money on the the plenum under the widscreen being full of water due to blocked drains and the water is getting into the ecu both mine and my sons A4 had a good gallon or so of water in there that we had no idea about untill reading up on this forum