3.0 quattro starting issues

**sergeantcookie** · 20-08-2017,07:24 PM

Hi all
Recently bought an Audi A4 B6 convertible 3.0 V6 Quattro.

All was good until I drove it to my local supermarket the other day. When I come from out the shop the car had trouble starting, but I managed to get it going in the end (think I pressed on the accelerator). Anyway, never really thought any more about it and just saw it as an inconvenience more than anything. A couple of nights ago, I went to the supermarket again, come out about 10 mins later, and again the car wouldn't start. This time the accelerator trick didn't work either. After about 20 mins of trying I decided to call the RAC out. When he turned up he did the usual stuff and pretty much the car started straight away for him (but the ABS and EPS lights stayed on - they also appeared a couple of nights ago, but went out next time the car was switched on).

He asked a few questions that I found odd at the time of him asking but after asking him why he asked it made sense. He said 'Has the car been standing for some time'? To which I answered yes around 3-4 months. 'When you last had trouble starting it, did you press the accelerator?' Yes, yes I did. He then plugged in his diagnostic machine, and after some connection issues, it finally connected and the ECU threw up faults on pretty much everything, he said some could be down to low voltage, but also could be a problem of condensation in the ECU? He showed me where to look for water (one of the fuse boxes on the O/S of the bonnet just under the wipers, and said he can see moisture in there so it needs to be dried out. He also said it could be an issue of over fuelling, thus flooding the engine as both trips to the supermarket have been straight from home, which is less than a 2 mile trip.

I went out in it tonight, and taking into consideration what he told me about short journeys, I went the long way round to my destination which was about 4 miles away but ended up doing something like 6 or 7. After an hour or maybe longer of the car been sat there switched off, I got back in it and it wouldn't start. I tried several times, using the accelerator again, and it finally fired up after several attempts. When I arrived home, I pulled into the drive and switched it off, and thought I'd just give it a try to start it back up, and low and behold, it wouldn't start.

So, has anybody got any ideas and has the RAC guy got it spot on, as he says this can be a common problem for cars that sit around for a while (getting condensation in the ECU)?

**calum** · 20-08-2017,07:51 PM

It won't cost you anything to dry it out so nothing to lose. Other contenders for poor starting are fuel pump relay and coolant sensor and engine speed sensor G28. Also check the connectors to the ECU sometimes they furr up.

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**sergeantcookie** · 20-08-2017,08:25 PM

What's the best way to dry it out? Is it the ecu under the cover I mentioned previously, and by unplugging it, nothing will 'mess up' will it?

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**calum** · 20-08-2017,08:30 PM

Originally Posted by sergeantcookie

What's the best way to dry it out? Is it the ecu under the cover I mentioned previously, and by unplugging it, nothing will 'mess up' will it?

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Rice is good for drawing out moisture, disconnect battery then disconnect the ECU, it won't present any problems.

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**sergeantcookie** · 20-08-2017,08:49 PM

I'll look into doing it one evening this week. I suppose I won't know for sure if it was the ecu at fault until it happens again

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**Scott K** · 21-08-2017,02:04 PM

Sounds like the battery could be shot. Any idea how old the battery is? Low battery also tends to throw up error messages.

**sergeantcookie** · 21-08-2017,02:40 PM

Originally Posted by Scott K

Sounds like the battery could be shot. Any idea how old the battery is? Low battery also tends to throw up error messages.

Havent got a clue mate. The rqc guy said try the ecu first with moisture but then also mentioned low voltage. So I don't know?

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**sergeantcookie** · 21-08-2017,08:20 PM

I managed to get the battery out which tbh was not the easiest of tasks. Unfortunately the surrounding area was absolutely swimming in water. I haven't managed to remove the ecu cover yet as I've had to order a wiper arm puller.

Where are the drain holes, does anybody know? I've removed most of the water but I guess there's a blockage somewhere

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**fourringsrus** · 21-08-2017,08:56 PM

There are rubber gromets, one below the battery and one below the servo on the other side of the skuttle.
They fill up with leaves , dust etc and cause a trap for rain water etc.
Take away the battery and poke about until you find the gromet, I used a straightened out coat hanger to prod through the gromet until the water drains away, then dry with a sponge/cloth w.h.y.Be sure to check for non blocked area regularly.
Same on the other side ,but it can be awkward getting under the servo.
Your ECU lives in the well ( no pun intended ) near your battery and if exposed to excessive water ingress, will die giving you all kinds of hassle.
Regarding overfuelling etc, I dont think so, regarding battery age/condition, as said above, this if in a lower than suitable charge hold ability, will turn your engine over but not necessarily give enough for the starting system to perform to its prime.
As an example, car stands a while and loses a small amount of charge in the tired battery but just manages to start your engine, while starting the engine you pull a large amount out of the battery, which is already weak.
Park at super market after not giving the battery enough charge to replace what was used during the initial start.
Get your grocery package and return to the car and demand max power again to start and there simply is not enough charge stored.
Sometimes you will fluke it and the car starts without any detection of the battery weakness, another time, no go.

So as said above clean and dry plenum chamber drains, some people have just shoved the gromets straight through and left the drain holes unobstructed, this process costs nothing but a little time and messing about.
Contemplate replacing the battery with a fully charged known quantity.
Have check done on alternator charging circuit.

Read forum archives search on plenum chamber drain bungs/gromets on b6 a4 it has been covered and you may find simple guide/how to illustrated for your ease.

Good luck

Stuart

**sergeantcookie** · 21-08-2017,09:02 PM

Wow what a great reply. I have seen one of the large grommets you are on about but didn't dare move it as knowing my luck it would have run straight into the inside of the car. I thought the ecu was in the black box top left corner. When I can remove my wipers I will get to it to have a good look inside and dry anything out that needs it.

I'm going to get a new battery as I don't know how old the other one is and it looks as though it's seen better days.

I'll look into the plenum chamber stuff

Many thanks again

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