Audi A3 2.0 tdi (bkd) issues help needed please👍

[Gaz_hay]

Hi, new to this forum so hope I'm in the right place....
I'm glad to be part of a new forum after coming from a Bmw forum...

Just got a Audi A3 2.0 tdi (bkd) engine
And Idle is very ruff.... The rev counter doesn't glitch when idling ruff....
And it's also goes into limp mode now and again when I put my foot down...

I have changed the wiring harness ( common problem I've been told)
Changed glow plugs same time
Full service
Recent egr valve (new 1 before I bought car)
I've checked it's clean..
And the valve under the egr valve I've also replaced...

I fitted a egr blank plate and the idle wasn't as ruff.... And I found strange is the blank was in for 800+miles and there was no carbon build up on the plate whatsoever ever!?

I removed plate and the idle went back to worse...

I'm out of money to book it in to get sorted so any advice would be great as I want this car sorted ASAP as I use it daily for work...

Many thanks in advance and do hope this forum is as good as the Bmw one for helping issues...

Thanks again👌👍

[Crasher]

So you have never had a code read done?

[Gaz_hay]

Hi, thanks for quick reply,
Yes forgot to add when it started idling ruff, no engine management light but it got plugged in by a local garage and they said it had a fault something like;
Cylinder 4 glow plug circuit fault!?

So he advised me its most prob actually the loom so it was changed to the upgraded 1 by myself and I changed glow plugs same time as I was there...

Thanks ,

[Crasher]

One glow plug does not a wobble make. Check the fuel filter to see if is black (inside that is, before Zolly the Welsh wizard makes an appearance! ).

[Gaz_hay]

Hi, yes when I changed the filter the diesel was black in colour , and oil substance on the fuel filter pot...
But was told its normal to have a bit of oil in there due to the fuel set up on the car!?

Wasn't any thick oil just looked like someone has dyed the fuel black if you get me?

Thanks for your input on this matter,it's very much appreciated and hopefully get to bottom of this...

Thanks again,

[Crasher]

The fuel tank is contaminated with engine oil which alters the combustion characteristics (Cetane number) of the fuel. You need to replace the tandem pump on the head and flush the system out clean.

[Gaz_hay]

But when I fit the egr blank plate the ruff idle drops a unbelievable amount?
And what I found funny was the egr plate never got carbon build up on it was still shinny?

If you believe it could be down to the tandem pump I will buy 1 ....

Many thanks for your help and guidance very much appreciated nothing beats the help of fellow owners....

Thanks again,

[Crasher]

EGR stands for exhaust gas recirculation, its function is to introduce exhaust gas to lower the temperature of the fuel bun which reduces NOX emissions, it could be that this temperature drop is causing problems with the fuels Cetane reduction caused by oil. If the filter is contaminated the entire fuel system will be so if it is affecting the engine yet or not, it needs changing anyway.

[Gaz_hay]

Utterly true, I'm going to get 1 this weekend from euro car parts 210pound,
What is the best way to flush the system as I have a full tank of what now will be black rubbish.....
Thanks for your input👍

[Crasher]

We use the diagnostic system to empty the fuel tank using the lift pump with the fuel coming out of the filter feed pipe and clean the fuel filter case and fit a new element. Then we put it a couple of gallons of fuel from our big ready can and tell the owner to put a full tank in on top of this with a bottle of Red Line Diesel Plus fuel treatment, after a couple of tanks we fit another fuel filter to check the system is clean and usually it is spotless. I would say around 10% of EA188 PD TDI's we service has engine oil in the fuel.