drdan131

here a strange problem.
i had a mechanic change my starter on my 92 sc400.
a week later the car runs on 7 cylinders,. the mechanic finds i have no compression in cylinder 7. I take it to the lexus dealer who does a compression and leak down test to find the same, no compression.
i take the car and it limps home. the next day i start it and it runs on all 8 cylinders, i did not do a compression check but i could tell, i drive it for awhile like about an hour and then it starts running on 7 cylinders again.
the car is possessed. i heard it could be carbon build up on an intake valve, so i ran some water through a vacuum hose to get rid of carbon. old school trick i guess, but, it ran good and then came back.
any ideas, its driving me crazy.
how could a cylinder have no compression then work fine.
all ideas appreciated
thanks

Ali SC3

iTrader: (10)

that is a strange problem. i dont think carbon buildup will be giving you zero compression.
do you have any other signs of a blown headgasket or anything like that. low on coolant, oil in coolant, sweet smell from exhaust? let us know.

stockhatch

iTrader: (12)

Does it make any kind of valvetrain noise? Maybe a bucket is seizing in the bore causing the valve to stick open or float prematurely... Thats my wild guess LOL. When they did the leak-down, did they not trace the source of the loss?

99SC42

iTrader: (44)

lol do this ok!
start the engine, unplug the injectors one by one and see if the idle changes!
do same on the spark plug unplug the wires going to them one by one and se if the idle changes.
I think it maybe be fuel or ignition related.