2000 Saturn SC1 cylinder mis-fire


ashton2093
03-09-2006, 02:14 PM
I have a 2000 Saturn SC1 with a service reading saying that cylinder 1 is mis-firing. I have had this car at a local garage and he has checked the compression and it stands at 160psi, also he has tried different plug, wire and fuel injector and still do the same. When going it runs fine but when it idols around 1000 rpm's, it missesto beat hell. If anyone has any ideas with this please help.

drew300
03-09-2006, 03:22 PM
My '99 SW1 acted up too.
The intake gasket fails, and lets in air, so you lean out and misfire.
To check it out, with the engine running, (idle), spray some carb cleaner, throttle-body cleaner, around the intake gasket area. The revs will pick up at the leak.
Check the gasket, and if nothing, check the injectors, they seat in a "rubber" seal.
My gasket failed at cyl 1, and was close to failing at cyl 4, which would have let coolant into the engine.

saturnspeed_12
03-09-2006, 06:20 PM
yeah, sounds like an intake gasket.

but that compression, what was it across all the cylinders? unless he did it wrong, your compression is LOW! minimum limit is 180psi. you piston rings are either carboned or valve stem seals are leaking too.

ashton2093
03-14-2006, 09:19 AM
I want to thank you two for the helpful information, it was the intake and I changed it over the weekend and the car now runs fine.
I do still have to find out why the compression was only at 160psi when you were telling me it shoud be 180psi. Thanks again for all your help.

drew300
03-14-2006, 01:42 PM
My thoughts: if it runs fine, with good fuel economy and low oil consumption, don't worry about the compression, maybe it was measured wrong, or the guage suspect.
However, if it ran poorly, I'd check further.

saturnspeed_12
03-14-2006, 03:35 PM
id say possible piston rings carboned. other then that its the valves not fully seated due to carbon. i doubt it will be anything else. if the gauge worked fine and it was done right, then its mostly likely a carbon issue.

what you can do is a piston soak with marvel mystery oil or gm tec or even seafoam. i prefer one of the first 2. all you do is pour it into the cylinder, most do it while engine is still warm not hot, put the spark plug back in and let it set for at least 12 hours. now all you really need to do is pour enough in so it can completely cover the piston. you can add more if you dont want to keep checking to make sure its full, but then you will need to crank it with the fuel pump disabled and ignition module disconnected(below coils) and spark plugs out to pump left over fluid out. its best to do this near an oil change.

also, it might be best to crank it after its set for you because you have a sohc, which has a dish in the piston so it can hold the fluid there and maybe be hard to start or cause some misfires till its completely out. and it might smoke a bit.

sierrap615
03-15-2006, 03:49 AM
don't worry about the 160 psi, assuming it was done dry with only 5 cranks and the crapped out gasket its to be expected.( compression test on most engines is 5 compression strokes vs saturn's specified 10 compression strokes)

saturnspeed_12
03-15-2006, 03:08 PM
don't worry about the 160 psi, assuming it was done dry with only 5 cranks and the crapped out gasket its to be expected.( compression test on most engines is 5 compression strokes vs saturn's specified 10 compression strokes)

probably because of poor piston/ring set up. need the oil to get to the rings to increase the compression. although i wouldnt crank it that much anyways. pour some oil into the cylinder then crank it.

sierrap615
03-16-2006, 04:06 AM
pour some oil into the cylinder then crank it.

thats a wet test. when testing compression you take both dry and wet readings(compression should increase with the wet test)

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