P0301 Misfire
 

Hello All - I've posted before for my son's 1998 chevy blazer. He returned home from graduating as a Marine, but now gone again and his car still isn't working. Maybe you all have some ideas. We put it on the diagnosis and received a P0301 misfire. Know it is cylinder 1. Replaced Cap/Rotor, Plugs/Wires - know there is a spark! We then did a compression test on it last weekend. Average cylinder was 95 PSI - except cylinder 1 - it started at 30 and went to 90 by the 4th engine turn. We then added some oil into the cylinder and it went up to about 150 psi. Not sure where to go from here. Book says - if only one cyn gradually rises - most likely a piston ring. The car has approximately 80K on it. Runs great otherwise. Runs better at higher speeds (highway) than it does idyling. What would be the next test? Leak test? I am reluctant to take it anywhere for repair.

If anyone lives in Socal and knows cars - please email me. Thank you all for your help!

Marine Mom

could be a faulty spider injector

The wet compression test yielded more compression..alot more. So, that tells me that the rings on that cylinder are bad.

You can do a leak test but, it will not reveal much more than what you have already done.

And when you say average 95psi are you taking all the compression readings adding them up and dividing by 6 to get your average??

You really should have about 140psi or better on a compression test....depending on the configuration and design compression ratio of the engine; 155 to 170 or so is typical for engines in good shape with ratios of 8.5 to 1 or better.