A4 avant new injectors

[TimR]

Hello everyone!

My name is Tim and i am a new Audi owner and new member on the forums. I have been looking over the forums for quite a while and finaly decided to join the club.

I am usualy not the one to seek help, much rather helping others with problems, but i am stuck in a situation that i hope some qurus here could help me find a solution to.

The car in question is an b8.5 a4 avant, 2015 year, 110kw CJCD engine code. It has about 110000 miles on the clock.

I service it myself so the things that have been done (preventitive services) are:

-oil and all filters (castrol 5w 30edge)
-new sachs clutch and flywheel
-KMB oil pump mod (balance shaft and hex drive)
-timing belt and wp (all timed with the correct tools)
-new oem valeo egr valve with cooler,
-new auxilary belt with tensioner
-new glow plugs

Let me get out of the way firstly, the car starts hot and cold everytime, maybe a little shake for a second or 2 when starting the car after about 10 hours, but heard this was normal.

The problem i am having now is that ive replaced the injectors with oem bosch reconditioned ones.

After one day the deviation quantity at idle is as folows (warm engine):

Idle speed: 812rpm
Iq idle average: 5,34mg

Averages after 2min of idle:

Cylinder 1: 0,22mg/str
Cylinder 2: 0.02mg/str
Cylinder 3: -0.39mg/str
Cylinder 4: 0.09mg/str

Then i swaped injectors and put nr1 on nr2, and injector 3 on nr1 the readings were

Cylinder 1: -0.44mg/str
Cylinder 2: 0.22mg/str
Cylinder 3: 0.04mg/str
Cylinder 4: 0.10mg/str

Al injectors were coded everytime.

Is this just the tolerance of reconditioned injectors, or are these numbers completely normal, and i should leave them alone and check again after say 500miles?

I hope someone more familiar with these deviations could help.

Also car has lots of power and torque so no problems there.

Anyways i hope we can find a solution and, looking forward to contributing to the forum in anyway i can

Cheers

 

[TimR]

Bit of a bump... checked compression today and it is 24-25 bar on all cylinders. Also tried to remove the auxilary belt to se if any of the rollers (especialy the alternator pulley) is causing this. No change whatsoever. I am running out of ideas... help would be grately appreciated

 

[Owyn]

Looking at this
https://www.audi-sport.net/xf/threads/quick-vcds-injection-quantity-deviation-question.255021/
All looks to be in spec.

What was the reason for changing the injectors?

 

[TimR]

Hey and thank you for your answer. Yes i have already seen the posts that you linked. Still think that the numbers should be closer to zero.

The reason for changing the injectors was purely preventitive, no real issuses with the older ones. The only real issue with the car was the dmf which i changed due to juddery take off (its a manual 6 speed).

I am have just been looking into this injector deviation for the past 2 months and the high numbers are driving me nuts since i cant pinpoint the reason.

Again new injectors, good and even compression, good mileage and power, no tapping noises that i can hear from the lifters so just running out of ideas

 

[Owyn]

Good stuff, never really heard of injectors being changed that aren't causing problems.
The numbers look pretty consistent for each injector so I'd suggest if you want them to be closer to zero then you'll need a new injector.
I don't really see the point though, I'm pretty sure that if the injector gets so far out of spec that your car can't compensate it will throw an error light. As it is your car is adjusting for a slightly worn injector.

 

[TimR]

Yes im going by the saying rather be safe than sorry (seen quite a few engines bit the dust from leaky injectors whine i worked at a repair shop).

It is just strange that all 4 new injectors can cause such deviations.

Also looked at the HPFP and there are no metal shavings in the fuel.

And the new numbers i am seeing are

Cylinder 1: 0.33mg/str
Cylinder 2: 0.04mg/str
Cylinder 3: -0.48mg/str
Cylinder 4: 0.00mg str

That is with engine warm.

When cold the numbers on cylinder 1 and 3 can go up to 0.75 and -0.75

 

[jakm15]

Slightly off topic but why did you modify the oil pump drive? As far as I'm aware from around late 2010 the modified oil pump hex drive was fitter and definitely by the time the b8.5 was out.

Sent from my moto e5 plus using Tapatalk

 

[TimR]

The pump was modified since it is stil the same design only a bit longer hex drive and deeper hole. The fitment is still losse and it gets quite worn over time. Its still a faliure point acording to a friend at vw spare parts