Cold starting issue 2.5tdi V6 BAU

Heya guys

I’m completely new to diesels and I know sort of how they operate. I’m sure I can learn a lot from this forum though.

I recently bought and have just started driving a 2005 audi allroad with the 2.5tdi BAU engine.

It seems to have an intermittent cold starting issue. Sometimes it will crank and crank for what seems like ages and eventually fire. And other times it takes a little longer than I'm used to in a petrol car. Might be normal, I don't know.

I only have one fault code which is

00560 - Exhaust gas recirculation system
08-10 - Control limit Surpassed - Intermittent


Could the EGR valve being stuck open with the build up of carbon cause a cold start issue? I.e. sucking air in through the exhaust instead of through the inlet/MAF. Could I unplug the MAF and try to start it to test this theory? I know on my old 1.8t petrol passat when the MAF went bad. I just unplugged it. Ran great until I got a new one.

It starts great when its warm and doesn't seem down on power but I've only driven it like this I guess.

Any help would be greatly appreciated.

Hello

While we never had your engine code in this side of the pond, we do know that a stuck open EGR can cause a no start/ hard start condition. Regarding your idea of disconnecting the MAF to test this, it will only make the ECU use default MAF values because the actual MAF is disconnected. The best way to test a stuck open EGR is to remove it and confirm there are no obstacles for the flap to operate. Is your car EGR controlled by vacuum?

Out of curiousity, what is your definition of cold in Somerset?? Canadian tdi's regularily start at minus 20 or minus 25 Centigrade every day.

Carlos_TJ said:

Hello
While we never had your engine code in this side of the pond, we do know that a stuck open EGR can cause a no start/ hard start condition. Regarding your idea of disconnecting the MAF to test this, it will only make the ECU use default MAF values because the actual MAF is disconnected. The best way to test a stuck open EGR is to remove it and confirm there are no obstacles for the flap to operate. Is your car EGR controlled by vacuum?

Click to expand...

Oh that's interesting. Potentially could be the EGR valve then. I need to clean/replace the egr valve if its not function correctly anyway to get rid of the engine light. So it's probably worth doing it sooner rather than later. Looks like a PITA job on this engine though.
Yeah its a vacuum controlled one.

miningman said:

Out of curiousity, what is your definition of cold in Somerset?? Canadian tdi's regularily start at minus 20 or minus 25 Centigrade every day.

Click to expand...

-2 C on the coldest mornings. It was about 4 C yesterday morning when it cranked for about 10 seconds until I stopped, then I cranked it again and it fired straight up with some smoke out of the exhaust.
And even after work when it was about 10 C it cranked for about 3 seconds before starting.
So not that cold. Im sure it would start and at lot colder if it was functioning correctly.

Trying to do some fault finding or at least narrow down the cheap stuff according to your forums Pinned post.
My car is a 2005 so has a lift pump in the tank. Couldn't hear it so checked power - no power with ignition on but power cranking (just cranked it for a second). I did read thats how its meant to be though?
Need to go grab some wire to jump the pump to see if it is working.

Gonna check the fuse for the glow plugs but I need an 8mm for get to it. Tried to pull a glow plug connector off to check for power but couldnt get my fingers in there. All my tools are down at my workshop.

A friend suggested it might just be a clogged filter. Checked the service history and the last one was 40,000 miles ago so that might be the case. Car is due a service anyway.
While I was in the service history I saw the car had a reconditioned injection pump 6 years ago for a non start problem..... when the car was 6 years old. So, yeah.

Fuel filter changed for a genuine audi one. No difference. Checked the fuel tank lift pump while I had the pipes off and it's flowing ok.
Also changed the valve thing on top of the fuel filter while I was there.
Checked the fuel for contamination and all looked good.

Checked the glow plugs today for power, they all have power. Also checked the resistances and according to the pinned post on here they are way way off.

Should be 0.5 to 1.5 ohms according to that and I got:

Looking from the front of the car into the engine bay this is the left hand side

4.68 K ohms
0.544 K ohms
230 K ohms

And the right hand side

0.512 M ohms
184 K ohms
0.53 M ohms

Checked them a few times and they were pretty much the same readings. Although the did increase if I held the probes on there longer.

Oddly i didnt get a fault code for this though

Ordered some new plugs now.

Just thought I'd see what the outcome was if I tried to start it with no plugged in glow plugs from cold. Same symptoms. So a little confidence is building.

Also checked after doing that to see if I would get a fault code for the glow plugs with them unplugged. Nothing.

It was the glow plugs. Fixed now. No fault codes though.