225 promax #4 detonation

[JayKen]

My '04 promax (86 hrs) quit running with no warning horn or guardian system shut down. After it quit it did give an overheat horn and would not turn over on trying to restart. When it cooled it turned over and started but was obviously dead on at least 1 cylinder. Checked the plugs and #4 had aluminum on it. #4 and #6 have 0 compression.
Had it on a DDT before I pulled it apart and it showed no fault codes and no diagnostic problems. The guardian system shows 100% available power. The tech who tested it said according to the DDT it should be running fine.
Upon tear down #4 is seriously melted on the bottom half, partially in the exhaust port but not fully as I would have expected. #6 looks fine:confused:. Any ideas why #4 would melt. I checked the reeds and injectors and they seem good. Running 91 octane with booster. Also any thoughts on the warning/guardian system with no warnings before meltdown. Thx, J

[SnakeEye]

Sounds like a bad tracker valve to me. Have you measured fuel/air pressures? It'll give no electronic warning if that's bad.

Also, check the low pressure electric pump.

~Snake

[JayKen]

tttttr

[JayKen]

Snake- No tracker valve on the promax. Not like the optimax.

[props4u2]

There's no such thing as a 2004 225 promax either. A 225x is completely different than a promax. Hard to say what the problem is but a ddt doesn't tell much as far as burning pistons. Could be a bad injector, faulty ecu, blocked water passages etc...


Lee

[JayKen]

Lee - sorry it is a 225x promax. As far as the injectors go the local tech sad the DDT diagnostic said they're ok. Cleaned the fuel rail and checked for debris, seemed okay. Injector test with 9v battery seemed good. Don't know about the ecu, how accurate is the DDT diagnostic? After checking closely it appears the seal in the head may have leaked. Maybe a warped head? Much history of these kind of problems on these motors?

[SnakeEye]

Silly me, getting confused by the american model lineup. I was sure that the new 2.5 OptiMax based motor we're scheduled to start using in F2 next season was called a ProMax something something. What's the story?

~Snake