Hard starting saturn

My sons 1998 SL1 Saturn 163,000 miles on it runs extremely rough when you start it seems like it is running on 3 cylinders. However after 10 seconds of reving the engine up runs fine. Once it warms up runs and idles fine all day but after you shut it off it exhibits the same hard starting.
It has new plugs and ignition wires on it.
I’m thinking a cracked coil that as it warms up starts to work properly but looking for some other opinions.

Could be flat intake gaskets, which expand and do a better job of sealing when warmed up

If it idles above 950 RPM in neutral and is just a little rough (barely noticeable) you probably need a new intake manifold gasket. That is a common issue on the SL1 engine because the gasket is not well supported around the #1 cylinder. Verify by spraying something around the gasket at the #1 cylinder and see if the idle is affected. Use a felpro for replacement, do not use a factory gasket.

I agree that Felpro makes good gaskets

Let me add a little more here, the condition you describes kinda sounds like a fuel injector that is leaking. The leak is very slow, but overnight, one injector leaks all the excess fuel in the rail down around one cylinder intake valve. When you start the engine, that cylinder will not fire until most of the excess fuel is pushed through, then in runs normal. The injector doesn’t leak fast enough to be an issue during the day.

Saturn’s don’t normally have issues with their injectors though.

check this too.



It could be a coil on the fritz, but I doubt it. As said above, this seems like it is an air/fuel mixture problem If your mechanic can use his real time scan tool to determine if it is running lean or rich, check the fuel trim etc, that would be helpful to finding the source of the problem. A lab scope on the spark signal would tell if there was a coil problem.