Another injector thread C6 S6 @ 126K Miles

A6 All/ S6 All
#1

I’m in the early stages of doing something with the injectors after I verify with smoke test that there are no leaks when cold. Getting misses on cold start & 2-3 seconds of cranking to fire when cold (but it has been cranking like that since I got it). The engine is at about 15-20K on the carbon clean and I’m pretty sure that would bring it back to running rightish again but yeah. The plan is to run VCDS to see what I can about the injector values and the a/f ratio, plus log misfires.

Has anyone here tried to clean out and replace the plastic baskets and debris with the injectors still installed? I’m considering that to minimize downtime and avoid pulling all of the injectors and having to redo the seals.

If that’s not feasible and they have to come out, has anybody used something like so?

AUTOOL CT400 Fuel Injector Cleaning Tester with GDI Test - AUTOOL (autooltech.com)

Thanks yall!

#2

Try opening driver’s door two times before cranking to see, if it fires up quicker. Wait 5-10 seconds inbetween individual door opens.

#3

Still about the same, even with priming via the key an extra time

#4

In my case key priming does not change anything at all, but opening a door two times does. I guess it’s becouse opening a door turns the pump for shorter amount of time, therefore fuel pressure relief valve does not stick open. To check for injector leak, have your engine warm up to operating temp, and then shut it off and monitor fuel rail pressure. If it rises, you’re fine, if it drops you have a leaking injector. In my case, injector cleaning didn’t cut it, and I had to replace them. Similar mileage to yours.

1 Like
#5

It looks like it rises when cold or warm, started at 31.50 bar right after power off and is at 40 within a couple minutes. There is another value for fuel rail that goes negative as it sits too but the main one goes up.

#6

In this case I’d check for manifold flap axle leak on both open and close position for misfires, and hpfp’s for insufficient pump ratę due to wear. I’d say it would also be wise to remove the injectors, and check their spray pattern.

Also, does it seem to start better, when left alone for a few days untouched?

#7

Not really it has always taken a few seconds to start. The manifold is new and the output test showed all was well when I installed it last year, I’ll check fuel pumps next time!