A6 3.0 BiTDI strange behaviour on cold start

[ibrica]

Hello everyone,

for the last couple of months, my car behaves strangely on cold starts.

It turns fine, and if i give it some gas right away and hold it around 1200-1300 RPM, engine starts shaking and the RPM needle goes up and down a bit.

It is doing so in the first minute or two when cold started. Also, if i give it some throttle, blue smoke comes out of the exhaust. It all clears up in a minute or two.

I've had the DPF delete and EGR off trying to resolve the issue, still no help. Injector seals and washers have been changed, new MAF fitted, still no help. Fuel pressure is fine, injector deviation within 0.3.

One thing i noticed, if i disconnect the MAF, the problem goes away. However MAF is literally 15 days old, OEM.

Otherwise, no problems with power, runs great, MPG is great, no smoke when the car is warmed up, no smoke on WOT.

Any help is appreciated.

Thanks

 

[ibrica]

I forgot to note that injector number 1 had a lot of rust on it, and was spiking up to +1.0

Here is a picture

 

[ibrica]

update, egr was stuck open

blanked it, all good.

egr is the cause of a lot of the problems on these cars

with egr blanked much better throttle response, better mpg

 

[TedA6Avant]

update, egr was stuck open

blanked it, all good.

egr is the cause of a lot of the problems on these cars

with egr blanked much better throttle response, better mpg

Hello, my 67 plate A6 3.0 biturbo has a similar problem, which clears itself up once warm. How did you diagnose the EGR as the problem? Many thanks.