2009 Vw golf gti 2.0TFSI engine broken

Hi all, I have a big problem with a
Vw Golf GTI 2.0TFSI BWA engine.
APR K04 hardware and software, APR down turboback exhaust, APR intake, fuel injectors, this car make 325 HP in the dyno test, the car is for street use and weekend track days, the car worked perfectly, in the street and in the track, one day the engine dead, we unassembled a engine and the #4 piston are broken, the piston melted, we repair the whole engine, we install supertech pistons oversize at 82,5mm, all parts brand new, we change a 4 Fuel injectors, because one injector damaged could generate the piston broken, after start the engine the car run good about 15 days and 560 km, and the engine started making a sound, we check a engine and the sound was by the #4 cilinder again, we unassambled a engine and the #4 piston are broken again, the cylinder are damaged, but the pistons 1,2,3 are perfect, the problem is only with #4 piston, we install other supertech piston and repair the cylinder, now to 83 mm over size in 4 cilinders, we check all in the engine , oil supplier, all tolerance, etc, and assambled the engine , the car start again, after the car work for 600 km, and the sound again, unassembled the engine and the #4 piston is broken and melted again, I dont know what happen with this engine, the other 1,2,3 pistons and cylinders are perfects, somebody helpme !!!!
attach some piston pictures
Remember all time is #4 piston



https://mfdd4g.dm.files.1drv.com/y4...Q4Re_-Zxg?width=578&height=1024&cropmode=none

Thanks

Post an Auto-Scan........

FOD!

Get a complete new engine, including turbocharger and an ECU that is stock...........

This is hardly enough pictures or information but that piston has suffered from lack of lubrication issue with incomplete or detonation combustion from most likely unregulated over boost & no mod for the now much higher compression of that cylinder due to displacement increase.

Moving to General VW/Audi Repair.

I suggest you contact APR for advice with their tuning parts.

-Uwe-

Oh, man... I hope I will have more luck. As i know, engine like this melted due to poor gasoline octane rate, bad injector(s), spark plug and of course excessive feet on the gas pedal...

You don't show pictures of the piston crown. Does the damage start at the top, or is it mostly just the side as-pictured? Knock/detonation or lean overtemp would start the damage at the top.

Piston #4 is furthest from both the oil and coolant pumps. But, marginal oil pump output would kill your bearings way before piston and bore scuffing starts, and marginal coolant pump output should be obvious on your temperature gauge, so I doubt the pumps themselves are at fault.

If you've lost the same piston three times to scuffing, and you're setting up your clearances and oil control rings correctly, that really only leaves a localized lubrication or overheating issue. You might have an obstructed coolant passage through the block or cylinder head that's blocking flow around that bore, or a clogged or missing piston cooling oil squirter. Also check to make sure you're not using an incorrect head gasket that might obstruct a coolant passage between the block and head.

Detonation starts at the top Jason & where pre ignition takes place before the spark plug is called to fire it or after!

Jack@European_Parts said:

Detonation starts at the top Jason & where pre ignition takes place before the spark plug is called to fire it or after!

Click to expand...

I agree, and stated such:

jyoung8607 said:

You don't show pictures of the piston crown. Does the damage start at the top, or is it mostly just the side as-pictured? Knock/detonation or lean overtemp would start the damage at the top.

Click to expand...

The OP shared what appears to be two pictures of the same piston from different angles, or at least they're on the same table with the same stuff in the background. OP did not show us the top. If there were detonation, the top seems like an odd angle to NOT share since that would be the area with the most damage. Instead, we have two views of the rings and skirt. On one of them, the top radius we can see is perfectly intact. On the second, we can see one place where there's a few mm chipped off the top radius, but that could have been chipped off from the side, and it's otherwise perfect.

The balance of evidence OP has shared so far doesn't point toward detonation. I'd still like to see a picture of the top though.

After rebuilding again if you do it would be good to datalog of the knock on all 4 cylinders. It would be good to try making pulls up to about 4000 rpm only and checking for knock.

I agree, and stated such:

Click to expand...

Indeed.........

The OP shared what appears to be two pictures of the same piston from different angles, or at least they're on the same table with the same stuff in the background. OP did not show us the top. If there were detonation, the top seems like an odd angle to NOT share since that would be the area with the most damage. Instead, we have two views of the rings and skirt. On one of them, the top radius we can see is perfectly intact. On the second, we can see one place where there's a few mm chipped off the top radius, but that could have been chipped off from the side, and it's otherwise perfect.

The balance of evidence OP has shared so far doesn't point toward detonation. I'd still like to see a picture of the top though.

Click to expand...

Or maybe too embarrassed to show the use of non trapezoidal pistons with trapezoidal rods?