detonation cyl 2 only/ cracked piston

[buddy3824]

pictures speak for themselves. this is cylinder #2 piston. I was having massive oil blowby in motor (smoking out vent in vc at idle) and decided to build up. I find this piston in this shape to my amazement. The other 3 pistons are perfect for 10k miles. had 145psi on all 3 of the others. What happened to this little guy? Guys in the local area say they have heard of the stock manifold cause number 2 cylinder to run lean?
I was running a small 16g with 680cc injectors tuned by vpc/gcc. aem wideband gauge, and truboost. never boosted over 16lbs. always ran it a little on rich side. I'm looking for answers and advice.
my incoming build is gonna include ecmlink v2 I bought of a guy, can this be the solution? or does anyone know if a SMIM will correct the problem? thanks

 

[johnmarines]

Wow!!!!

 

[brian9397gsx]

with your set up and how it happened on number 2 suggests a possible issue with your fuel injector. how old are they and have they been flow tested

 

[2slow4now]

How could the manifold cause a cylinder to run lean? The intake valve opens and the turbo jambs air in while the injector shoots fuel almost directly at the open valve. Fuel has to go in. If that cylinder was running lean it would have to be an injector related problem.

Who built the engine? I would be looking at that as a potential issue as well. Improper endgap on the rings could cause similar problems to what your seeing in the pic.

 

[buddy3824]

motor was rebuilt 10k ago with all new internals by previous owner, he rebuilds dms out his garage. the injectors are about 15k miles old. the previous owner had the number 2 cylinder go lean on him before and his result were as this, but he installed an egt gauge in that cylinder. but it stopped workin on me awhile ago. so i coulnt read air temps out of the cylinder.
intectors have not been flow tested. how and where can this be done?

 

[2slow4now]

The same problem in the same cylinder as the previous owner. What did he do to correct the problem? Just rebuild it? Was it actually rebuilt? Bored and honed? Did he show you any receipts? A brand new rebuilt engine then he sells the car?
If a cylinder was out of round it could cause damage that would get progressive. Which could cause hot spots which in turn could cause detenation.
Have you bumped 12v to the injector to make sure it functions?
Flow testing would have to be done at a shop that works with injectors.

 

[buddy3824]

he ran into family troubles and had to sell the car. it was driven on rebuild for about 4k miles over a 2 yr period, it wasnt his DD. he didnt do anything to correct i believe, aside form putting an egt gauge in the manifold runner of cylinder 2. as far as receipts and if was bored and honed or not. i do not know 100%. but he showed me his old head and the burnt piston that came out of the old motor.
I am going to be dropping my block off sometime in the next few work days at the engine shop, and they should be able to tell me if the cylinder is untrue in roundness.
A bore and hone is most likely needed as it does have some scaring. I would like to put 9.1 pistons in it.

As far as the injectors. I have not tested them yet. I will take em to work with me and hook em up to a battery and see what they look like and then ship em off to someone like FIC or PTE?

 

[buddy3824]

Just an update. had injectors flow tested, and they tested perfect!! Block is at the machine shop getting bored out now, he said block wasnt out of round, just needed to be clearance matched for pistons.

soooo.. wtf guys? driver on the ecu?

 

[pballer]

had a similar problem on my car woth #2. Couldn't figure out what was going on for sure, i figure it could have been pulses in the fuel rail? ended up adding 5% fuel on #2 cyl with aem ems...

 

[buddy3824]

ah yeah? so im not the only one then.. just out of curiousness, did you have stock intake mani??

I'm getting dsmlink, wonder if you can add fuel to individual cylinders that way?

 

[TSIfreek]

with your set up and how it happened on number 2 suggests a possible issue with your fuel injector. how old are they and have they been flow tested

I would also look into this as well as the injector voltage regulator driver box on the fire wall. Looks like detonation damage to me.

ah yeah? so im not the only one then.. just out of curiousness, did you have stock intake mani??

I'm getting dsmlink, wonder if you can add fuel to individual cylinders that way?

No you cannot add fuel that way.

 

[tode5tool]

i don't want to go against every ones advice about injectors or a fuel control problem. that could very well be the situation. but don't forget, parts do not all come in the same specs, it could have just been a faulty part, bad rings possibly making that cylinder run lean and then detonation.. idk just a idea.

 

[pballer]

ah yeah? so im not the only one then.. just out of curiousness, did you have stock intake mani??

I'm getting dsmlink, wonder if you can add fuel to individual cylinders that way?

ya, stock manifold but i doubt that caused it. I swear it looks exactly like my piston, mine was deffilatly detonation caused by lean condition