Calling New school Common rail diesel experts

[mjrstar]

Got the vcds working (man it's cool)thanks to @Alfashark, as I anticipated due to rough idle but smooth power delivery the injector deviation numbers are off...

Does anyone know what an acceptable deviation numbers might be? And is there a process passed just running the engine and plugging in the laptop...

 

2014 Audi 3 litre bitdi

 

 

[Alfashark]

I'm not too flash with C-Rail, but that might suggest a not so healthy injector on 3, with 2 not a whole lot better.  

Hoon some injector clean through it and give it some jandal?

I think Audi/VW forums might be able to shed some light.

[mjrstar]

Yeah I wondered if there is an averaging thing, that it you have one requiring a big plus, that it compensates withe some minuses across others so you kinda get back to zero ish..

Tempted to get one new one, bang that in an see where the numbers head.. I expect the injector themselves are going to be eye wateringly expensive..

[datlow]

Find vw equivalent P/N!? 

Rock auto/fcp/pelicon maybe 

[mjrstar]

Yeah the other variable is these engines are prone to eroding the copper washer at the end of the injector that seals the combustion gas in.. so maybe the injector does weird shit when it's seeing less compression..

I'm relatively confident I have at least one leaky seal..

[Doug Hill]

Check/measure injector leak off/return

Check injector seat for leaking. 

Most likely seats, but easy/fast to do a leak off/return volume test first 

[mjrstar]

23 minutes ago, Doug Hill said:

Check/measure injector leak off/return

Check injector seat for leaking. 

Most likely seats, but easy/fast to do a leak off/return volume test first 

Do I do this by capturing the leak off volume into a container at idle or something?

[Doug Hill]

Yup. Couldn't possibly tell you the spec for one of those though, sorry

[mjrstar]

I have done some more reading, one of the reasons for an increase in injector is to smooth the idle if the engine doesn't see the increase in energy from the firing of that cylinder. It might also be reducing fuel on the other cylinders as part of the smoothing strategy. So potential for seal being my issue.

Research suggests that over about 1.5 is greater than normal and requires investigation. So yeah the ~5 is bad.

 

[Motu]

With Mitsubishi's we used to do an SQL, small quantity relearn. It would smooth out the idle and they would make less noise too.

[mjrstar]

Pulled the injectors, #3 had no remains of the seat seal and needed a lot of encouragement with a homemade slide hammer. #4 also needed a slide hammer but seat seal was in tact..both had a lot of carbon build up..

The other 4 injectors looked like brand new and seat seals in good condition...

I switched 3 and 2 injectors around and the high deviation number switched to cylinder #2 so I'll order one new injector and see how it goes.

[mjrstar]

Engine is purring again (until next time)with one new injector.