car stalls and doesn't want to start on cold

[august]

Hi Everyone !

I have bought an Audi A3 8p 2L TDI (170 HP) STOCK 2005 with 120k miles, engine code BMN. After a month of using it with no problems I go a map for 200 HP installed. However, the next morning after the map was installed the car had problems starting, however, it started. After that the car would randomly cut out while town driving or very soon after starting the car. Although if I made it to the motorway I would have no problems. Sometimes when it cuts out it wouldn't start up again until I have waited for around 10-20 mins then it would start with no problem or some times it wouldn't start for a day or two and then it would start after many attempts. To the extent of my testing once I have driven it for about 20 mins it wouldn't cut out as long as I don't turn the car off and let it sit for around half a day. If I let it sit for 1, 2 or even 3 hours it normally would start maybe with a bit of a difficulty and wouldn't cut out. I have been to the mechanic 3 times. First time they said they got an error code saying the common rail is faulty. So they replaced it. no change.... then I had service due, so I got all the filters etc replaced. They noticed there was oil in the fuel pump system, so they changed the fuel filer twice to clean it a little bit.... No change. Then at the third visit they said that the low pressure fuel pump is not working and that the seal around the high pressure fuel pump is bad and that's why there was oil residue in the fuel system. So they fixed that and changed the fuel filter again.... no change. At this point I have spent around 700GBP and nothing has changed. I have read articles with similar problems and in few they refer to relays and the ECU. Does anyone have any ideas where I should start looking ? Or what I should tell the mechanic to look at ? Also, should I maybe find a different mechanic ;P 

 

Thank you and any comments would be much appreciated !!!

[cliffcoggin]

August.

It certainly sounds like a fuel problem and your mechanic seems to have done all the obvious checks. The only thing I can suggest is to get a full range of diagnostic tests done by a diesel specialist, not the local Audi garage, not a helpful friend, but a specialist in diesels.

Having said that, I worry that the problem started immediately after re-mapping was done. That is too much of a coincidence for my liking. I don't know much about mapping except that it involves altering the software in the ECU, so I wonder if that has been damaged somehow. Is it possible to reverse the mapping?

[august]

Hi, 

Yes I have called the place, and they said I can get the original map re-installed.

[cliffcoggin]

If you can get the original map re-installed at little or no cost that would either confirm or exonerate the map as a cause of the problem. However if it is going to cost a lot to change the map you have to balance that against the likely cost of diesel diagnosis and repair. Unfortunately I don't know enough to advise one way or the other.

[august]

I see, thank you ! I can get it done for free but it's the timing that makes it very difficult. because I never know when the car will start ....

[august]

They said it was one of the injectors, apparently it was causing a short circuit that's why the car wouldn't start and would randomly stall. Picking up the car on Friday so will find out if they were right ! 

[cliffcoggin]

Do let us know.