Just took pictures of my pistons with a borescope

[ChrisA5]

I just bought this car with really bad misfires on cylinder 2, changed the spark plugs and the coils, and the oil and went on a long 400 mile drive to bring it home. The whole drive was ok without any hiccups.
Its a 2011 CAEB engine, with 100k miles pistons were never replaced. They are the old style with the 21mm wrist pin.
The following day I checked for codes, car was ready for an inspection. It had no codes.
Then I thought to remove the spark plugs and take a look inside the cylinders with a borescope.

The top of one piston (Cylinder #2 is very clean) and piston #1 is cleaner than the other 2.
I wondered if I have a leaky fuel injector, I hooked VCDS, the fuel pressure does not rise after i shut off the car. In about 3 minutes it dropped from 4010 kPa to 3620 kPa.
In 500 miles the engine used 1/2 a quart of oil.

https://photos.app.goo.gl/sgfBQ4B8Y6YbKR8F8

I am not sure how to check for leaky injectors. Any help would be appreciated.
Thank you

[Theiceman]

best way to look for leaky injectors is on a cold engine first thing in the morning get in the car , turn on the ignition but do not start the car ..

go out remove plus and look in cylinders, if its wet ( or sometimes spraying in ) you have leaky injectors. This is usually accompanied by hard start when cold.

[ChrisA5]

best way to look for leaky injectors is on a cold engine first thing in the morning get in the car , turn on the ignition but do not start the car ..

go out remove plus and look in cylinders, if its wet ( or sometimes spraying in ) you have leaky injectors. This is usually accompanied by hard start when cold.

Hot or cold car starts very easily.

[flowhigh]

The rings are toast. There's a ton of carbon buildup everywhere. Unless the cam is making it look worse than it really is. Half a qt is pretty excessive.

[Smac770]

If you have a hot engine and shut it off and you don't see the high pressure rail rise to as much as 170 bar (idle being 40 bar, WOT being 150 bar, system limit being 200 bar (iirc)) during the heat soak afterwards, something would seem incorrect. Be it an injector not closed or a problem with the HPFP. I guess bad case would be the HPFP leaking it back through a leak into the oil. Maybe leading to the consumption issue? But as already noted, if you're burning at 1qt/500mi, probably about that time for pistons.

[Justin B8]

I replaced all 4 injectors (along with plugs and coils) and did a carbon clean of the intake valves/ports at about 112k (2012 CAEB). Might have been $400 in parts all in. If you suspect one injector, I'd replace them all while the intake is off.
I did the water pump/thermostat/hoses too, since it was literally *right there*. I'm using about half a quart every 2000mi, which seems acceptable.

[ChrisA5]

If you have a hot engine and shut it off and you don't see the high pressure rail rise to as much as 170 bar (idle being 40 bar, WOT being 150 bar, system limit being 200 bar (iirc)) during the heat soak afterwards, something would seem incorrect. Be it an injector not closed or a problem with the HPFP. I guess bad case would be the HPFP leaking it back through a leak into the oil. Maybe leading to the consumption issue? But as already noted, if you're burning at 1qt/500mi, probably about that time for pistons.

Its 1/2gt per 500 miles... that is how many miles i put on the car since I bought it.
Is there a procedure to test if the the HPFP is leaking gas into the oil ?
I figured that it would be better to just trouble shoot first, before i start changing parts, but I can't find a testing procedure. I know that it could be an injector or the fuel pump. The pictures of the pistons show 2 pistons that are cleaner than the other two. Could it be that leaky injectors cleaned the piston tops? I also know that the previous owner did a carbon cleanup a few months before I bought the car. I checked with the borescope and the intake valves are pretty clean.
And what really makes me wonder, these cars are known to throw codes for the slightest malfunction I did not get any codes yet.
Is there a place i can send them sample of the oil to tell me if there is gas in it?

[Smac770]

Iceman posted a check for leaky injectors. What was the conclusion of that?
I imagine if you're suspecting fuel in the oil and don't smell anything, you'd send some of the oil off to be tested. What's that place people always send their oil for analysis, Blackstone? https://www.blackstone-labs.com/
Yeah, 1qt / 1k miles then. So not good, but not horrible. I'd run it some more and try and get a better feel of what's going on then before pulling it apart for pistons. If you do have injector issues, might be part of your issue. Might try new PCV too, if that one is original/old. Guess you have the black cap if it never had oil consumption stage 1 done.
Are the injectors the original ones? I'd just straight up replace them. I replaced the ones in mine after 100k miles on them, coated and clogged. I had high positive fuel trims, slowly growing over the past years. What are your fuel trims? Though if yours are leaking, guess you'd have negative trims. And then if it's a mix of clogged and leaking, maybe your trim looks "normal".

[ChrisA5]

Iceman posted a check for leaky injectors. What was the conclusion of that?
I imagine if you're suspecting fuel in the oil and don't smell anything, you'd send some of the oil off to be tested. What's that place people always send their oil for analysis, Blackstone? https://www.blackstone-labs.com/
Yeah, 1qt / 1k miles then. So not good, but not horrible. I'd run it some more and try and get a better feel of what's going on then before pulling it apart for pistons. If you do have injector issues, might be part of your issue. Might try new PCV too, if that one is original/old. Guess you have the black cap if it never had oil consumption stage 1 done.
Are the injectors the original ones? I'd just straight up replace them. I replaced the ones in mine after 100k miles on them, coated and clogged. I had high positive fuel trims, slowly growing over the past years. What are your fuel trims? Though if yours are leaking, guess you'd have negative trims. And then if it's a mix of clogged and leaking, maybe your trim looks "normal".

Thank you!. Your trim explanation is probably why I have no codes. I am not sure if what is shown on top of the piston is oil or fuel, and I am very puzzled as to why those 2 pistons are so clean on top. Only times I saw clean pistons like that was when antifreeze was going into the cylinders. But I have no coolant loss, and I have no overheating issues.
PCV is new.
Thanks again!!!

[ps2cho]

You're looking at a full rebuild anyway from the oil burning and rings that are toast - just replace the injectors at the same time. Hope you got it for a steal price.

[TomsMR2]

The test for leaking injectors is peeking down the spark plug hole and looking for clean pistons. DI motors leave a thin black coat on the piston face. Leaky injectors clean a patch off exactly like whats pictured. You got bad injectors.

Check your VIN with audi, those are covered 10/120k. You might get lucky and still be in time.

Leaky high pressure fuel pump gives weird long term fuel trims and sets rich at idle faults. The oil will REEK of gas, its unmistakable. Also, if you pull the HPFP you'll find black sludgy buildup on the lifter. The pump rod does not typically get dirty, until gas gets in there. This has nothing to do with the piston face cleaning you're getting, thats injectors.

Leaky injectors do all kinds of bad things to the engine that manifest over time. It'll kill the crankcase breather valve which causes sludge, which causes oil consumption, and those last two blow out your front and rear mains. Get ready to do some spending to get things ok.

[ChrisA5]

The test for leaking injectors is peeking down the spark plug hole and looking for clean pistons. DI motors leave a thin black coat on the piston face. Leaky injectors clean a patch off exactly like whats pictured. You got bad injectors.

Check your VIN with audi, those are covered 10/120k. You might get lucky and still be in time.

Leaky high pressure fuel pump gives weird long term fuel trims and sets rich at idle faults. The oil will REEK of gas, its unmistakable. Also, if you pull the HPFP you'll find black sludgy buildup on the lifter. The pump rod does not typically get dirty, until gas gets in there. This has nothing to do with the piston face cleaning you're getting, thats injectors.

Leaky injectors do all kinds of bad things to the engine that manifest over time. It'll kill the crankcase breather valve which causes sludge, which causes oil consumption, and those last two blow out your front and rear mains. Get ready to do some spending to get things ok.

Hi Tom,
Could this spark plugs be the result of a bad fuel injector too?


Thank you!!!

[TomsMR2]

Those plugs look pretty beat! The black chunky deposits on the right are typically what I see on high consumption CAEB's, unfortunately. The left just looks very worn.

*usually* when you have a leaky injector, the engine burns it all up once you put some load on the engine and rev it up a little and you wont get a super good plug reading. But not always, so reading plugs for that type of failure isnt too consistent or reliable.

[ChrisA5]

Those plugs look pretty beat! The black chunky deposits on the right are typically what I see on high consumption CAEB's, unfortunately. The left just looks very worn.

*usually* when you have a leaky injector, the engine burns it all up once you put some load on the engine and rev it up a little and you wont get a super good plug reading. But not always, so reading plugs for that type of failure isnt too consistent or reliable.

I will replace the injectors and see how it goes. At 100k miles a CAEB with the 21mm wrist pins most probably needs pistons, but it will work out better for me if I can delay this until next summer.
Thank you again Tom.