HI Greg, In your case regarding the dipstick, that is a unmetered air diagnostic (lean condition), so feel free to try it and monitor the MB's. You never know.
Regarding the fuel injectors, a contaminated/clogged fuel injector leaking down (when engine isn't running) will leak down and drip fuel into the cylinder and can cause difficult starting (flooded condition) not to mention leaking and diluting the oil !
Monitor the oil level and there is also a ross-tech video on fuel
rail system pressure ; there is a MB for it:
You can monitor the fuel rail pressure live to get a base line number and make note ; then, engine warmed up (coolant temp. at least 80 C) , turn off engine, then turn ignition / power ON, monitor fuel rail system pressure and within several seconds or so it should climb (because of engine heat soak increasing fuel rail system pressure ; if it doesn't climb 10 bar or more, you have a fuel injector bleeding off pressure and leaking fuel into the cylinder(s).
If you have one not atomizing the fuel (ie squirting a stream) that may trigger a rich condition.
I personally run
liqui-moly fuel system cleaner in the fuel (about one ounce per gallon of fuel) at least every other fuel up to keep the injectors clear! Maintenance is easier than replacement!
De-carb is always helpful, usually done when intake is removed for other repairs etc. I suppose if it were limiting air intake ,it could cause a rich code , but I would think you would also get misfire codes as well with severe to moderate carbon build up.
You will need to explore a exploded diagram regarding injectors ( only purchase Audi or the manufacturer (who makes them for Audi) ; new injectors come with some of the seals , but, I think there is one o-ring on the top that goes into the rail that it does not come with: check a Audi dealer web-site as they have exploded diagrams you can study or of course a factory manual for your vehicle. If you need to get the tool you mention, you can get one on
ebay or ECS tuning ; they are not expensive.
You can also check the 02 sensor with a (see YT videos). You need to unplug it and test with meter.
But,
you need to test first ; I don't recommend you start "throwing" parts at the problem ; that usually does not go well !!!
The Engine Control Module () controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and
www.engine-codes.com
