Detonation? Possible carbon build up? Which one?
 

I took my car out today to run it around a little bit. Anytime the car was close to going into boost it would start to stutter and get weird. For the most part it drove fine. It also didn't like going over 5500 rpm.

Now I drove it home today and it was doing just fine. I parked it and let it cool down some so I could go look at grounds, timing, possible leaks, etc.

Went to start it up and won't hold an idle. Ran a compression check and my front rotor has gone down to 90+psi and my rear is down to 70-80 psi. The rear has 2 good strokes and one powerless one.

Could something be keeping my sideseals down? Could I have detonated them without losing a full compression stroke?

The motor ran rich all day, and the only thing that kept it from running well seemed like a spark problem, so I'm assuming the gas wasn't getting burned up well.

Thoughts and opinions on this change in events?

BTW: This is a 6port high comp. motor with a stock S4 turbo on it.

blown apex seal

blown as in cracked? I can't forsee getting 70+ PSI with a blow seal. Especially two strong pulses and one bad one. I would expect 2 bad and one good for a blown seal. Right? Wrong?

blown apex seal.... with 2 compression strokes, ya ok

clamp your oil injection lines, stick premix in the tank, then add some Gunk engine cleaner or similar product to the oil and let it idle for about 20 mins... raise your idle speed until it holds it's own... this will help eat up gunk underneath those side seals and hopefully free them up...

if compression isn't fully restored, throw atf in the rotors through the spark plug holes (and leave them out), pull the efi fuse to stop gas from entering your engine, then turn it over for about 15 secs, let sit 45 or more, repeat several times... crank her up and hope for the best

if you still have the same problem, revert back to the first step until u don't, u have nothing to lose

oh and stick a big piece of cardboard adjacent to the spark plug holes to prevent the atf from blasting all over your engine bay :D

I don't have any oil injection lines. They've been removed in favor of premix. Unfortunately I never got a chance to put oil in the tank, but the motor had previously been running in NA form with premix gas. It was only out of the other car for a week.

Originally, the compression was 130 and 120...

This was 2nd or 3rd time i drove it with boost... but I have 550 prim and 1000cc secs.. Had my AFC set for 0's across the board to be safe until I could take it to a dyno... I just can't believe those seals could lock up that fast...

How does gunk crap clean my side seals if I put it in my oil? That oil can't get to my sideseals?

Thanks for the tip, I was going to give the ATF trick a try... I just wasn't sure if it was worth doing

nah on second thought, dont even bother with the atf... use seafoam in the champers instead... it's 100% petroleum and will lubricate as it dissolves buildup

small amount of oil gets by your oil seals and reaches the side seals normally... with the cleaner, the oil get's real thin and more will reach the side seals... it takes time tho, that's why i say 20 mins instead of the 5 mins in the directions on the cleaners... im suggesting this step first cause the K&W or Gunk brands at autozone work well... if your oil wasnt already black, it will turn black within the first minute as it dissolves gunky oil... dont rev the engine at all, especially with a turbo

So... the verdict is in...

Apex seals are A-ok.. unless I flattened a spring? I took the turbo and etc. off and turned the motor by hand to line up each apex seal at the exhaust. Took a good look and they're all fine with no cracks and they're all there.

There's a decent amount of crap and build up around them. It's not black though, it's kind of greyish.

I've read mixed reviews about using products like seafoam. Should i be trying to dump/spray that in the intake while the car is running? put it in my gas tank? Put some in the spark plug holes?

Would ATF be a better solution at this point and time?

If she was gonna blow.. chances a side seal would have gone are far less than an apex, right?

Pulled a vac tube and ran water into it. After doing that for a little bit (about a 20oz bottle of water), I ran a compression test.

Compression went from 70 at the rear to 90... front went from 90 to just a tad over 100...

so.. should I try to suck some ATF through? some Seafoam? what's going to be the least dangerous thing for my motor to try and get back well above 100 on both rotors??

I've read alot of things and all seem to have their ups and downs... what's best for restoring compression to a motor that was once 120/130 front and back...

was this a build on used parts?

the turbo, mani's, rails, etc. were used... the motor is a mazda reman with about 55,000 on it..

about 2 months ago, it tested at 130 front and 120 rear.. or the other way around.. don't remember anymore..

I ran it for a bit, did the turbo swap... turbo I put on was in HORRIBLE condition.. never even got to boost the motor, the turbo was just dumping oil into the exhaust...

Took off turbo stuff.. ran car as NA for a month.. just taking it back and forth to work (18 miles each way)...

Swapped it into different car... motor was running good... came home after taking it to work for one day... took it out to get some mileage on it... now it won't hold an idle...

Comp tests were extremely low... ran it all day with the SAFC set 6% less than normal at 800, 2400... at 0 for 4000, 6000 and 7200...

Believe car was running extremely rich during my test runs and etc... now it seems like the seals are stuck... cleaning it out just by steaming it helped a little...