Shake at idle, PO303, low compression

[MikeytheWiz]

2008 convertible normally aspirated. It has a shake at idle intermittent code PO303 Misfire #3. I checked compression: 1)175 2)175 3)100 4)180. Got no blow-by. I'm thinking flat camshaft. Any thoughts, opinions?
Thanks.

[ptcruisersteve]

I would suggest you do a wet & dry engine compression check on cylinder #3. Also do a engine leak down test to see if the leak is coming from the exhaust, intake or engine compression rings.
This will give you a better idea of where the problem might be.

[MikeytheWiz]

Originally Posted by ptcruisersteve

I would suggest you do a wet & dry engine compression check on cylinder #3. Also do a engine leak down test to see if the leak is coming from the exhaust, intake or engine compression rings.
This will give you a better idea of where the problem might be.

Thanks for the input. Unfortunately don't have a compressor to do leak down. I quit turning wrenches in 2003 and got rid of most of my tools and equipment back then. I will do the wet/dry test when I can, lol it's been long enough that that slipped my mind. Thanks.

[chuzz]

Check your intake for a leak. It might be as simple as replacing a gasket. And maybe look at the trigger magnet on the cam sensor. Sometimes people get over zealous when changing the cam sensors and over torque the bolts. That cracks the magnet. Those bolts have an INCH POUND torque spec.

[boatmoter]

even with 100 lbs of compression it should not be a missfire or dead miss, I would swap a sparkplug and injector out of a cylinder thats hitting and see if the miss switches to the cylinder you switched the parts with