Darko,
It was cylinder 4 and its an NT motor, so no boost and no fuel mods etc.
Amin,
You're right about the specs. Piston #4 apparently melted around the edge (1" total area) because the fuel mixture was too lean. I am confused as to how one injector could cause this problem especially because I had not experienced any problems with the injectors before.
The car was bought a year and a half ago in the US and has 130k kms on it.
Before last winter the car started to idle rough. I had the timing/balance shaft belt changed (100k on engine at that point - so it was time) and it didnt get better. It got worse over the winter and in April I had the injectors flushed and the throttle body cleaned. Put new plug wires and plugs in it, had the idle speed adjusted and the car ran 50% better but still had a rough idle, although not as bad as before.
Then this past month on the highway I experienced a power loss. The car suddenly couldnt hold 120km/hr and dropped to 90km/hr before returning back to normal after a few minutes.
So I decided to have the head done, new valve seals and injectors, hoping that it was valve related. Actually assuming that it was valve related, totally not expecting major piston damage. But low and behold the piston had melted in cyl#4 and scored the cyl wall.
I am totally confused and am now wondering whether to do an short block rebuild as the head has already been done.
First time I've seen something like this before.
Could the problem have been cause by sensor malfunction on the throttle body? Code check showed no faulty codes.
You can understand I am a little reluctant to put it all back together again for fear that the original problem may not be solved.
Thats the reason for this post. Hoping someone has had a similar problem and could advise....
