Ka24de Problem

[sldwys s13]

Just picked up a 89 coupe w/ a de swap evrything seemed ok and ran a little rough but nothing I didnt think a little adjustment to the timing wouldnt help but when me and my buddy started to go through the car I ran a compression test on it and the number 4 cyl. had 50psi but when I would run the car steady at around 2k or 3k it sounded and runs normal. Now me and my buddy are thinking it could be carbon deposits and the valves are sticking but without ripping of the head and checking I dont know took off the valve cover and the valve train is operating normally havent a clue was going to run some top end cleaner through like seafoam and see what happens but was wondering if anyone had any ideas I would apperitiate it Thanks Sean

[:: orion ::]

Check valve shim clearance. If that's within spec, I'd bet it's a bad piston (probably the ring land)...

If the valve shim clearance is too tight, it can hold the valve open and kill the compression #s and power...

- Brian

[Thee 240sx Owner]

Ya exactly what he said... also the valve seals maybe bad as well causing pressure to leak.

[xxtrizz]

You could do that tabl sppon of oil in the spark plug hoel and crank 15 turns and then retry compression as well.