mconway68w

iTrader: (2)

I've got a missfire in the number 7 cylinder. Compression is only around 90 psi vs 190+ in the others. My first thought is a cracked ringland, but the car does not smoke at all. Just a little rough at idle. It is FI so I know this is a typical breaking point. Can I have a cracked ringland with compression that low but no smoking? I'm hoping it's just an issue in the valvetrain.

Fastdriver1992

iTrader: (1)

yes you could. i had alot of smoke coming out of my breather on my motor(carburated) but yours might not b blowing smoke because u have the pcv hooked up to the intake manifold and its sucking in all the smoke from the blowby

mconway68w

iTrader: (2)

Gotcha, what about exhuast smoke? I'm not seeing any there either.

Fastdriver1992

iTrader: (1)

i never saw exhaust smoke on my car

theevette

iTrader: (2)

Broke valve spring maybe burnt valve

c0ncEpT

iTrader: (4)

Whats the plug look like?

Take the oil cap off. If the car is puffing a decent amount of smoke out of it while running you more than likely have a broken ringland.

mconway68w

iTrader: (2)

Haven't looked yet, but I guess the plug would look wet if it's cracked?

DoubleK

iTrader: (2)

I had the somewhat common #7 piston come apart on me last year (portion of the top ringland coming apart). I drove the car home 30 miles from the track with alot of misfiring, but no smoke whatsoever. When i finally took it apart, a 1/4 of the top of the piston was gone, i could actually see the top ring.

Also had a friend break the ringlands on #8 with very minimal smoking.

mconway68w

iTrader: (2)

$#!+ ... Guess i'm gonna burn it to the ground.

c0ncEpT

iTrader: (4)

Most the time the plug is destroyed as the piece of piston likes to bang around before it leaves combustion chamber.

Start it and take the oil cap off. That is a tell tale sign.