Hello. My brother's 2007 infiniti m35x is having a misfire in cylinder 5. I swapped the ignition coil pack and changed the spark plug but nothing changed. His car recommends 91 gas (premium), but I've been putting 89 for the past 1-2 weeks. Could that be the cause of the misfire?
Could that be the cause of the misfire?
Not likely, you'd be experiencing preignition ("pinging") if anything. Also that would affect all cylinders, not just one. You need to take a closer look at what's going on in cylinder 5. Starting with a compression test to rule out bad compression would be a good idea.
@chucktobias Ok Thanks. I'll get a compression test. The valve cover gasket is leaking as well. Could that possibly be a contributor? Or would that typically cause all cylinders to misfire and not just one?
Yes, if the oil is leaking down onto a coil or spark plug it can cause a misfire.The valve cover gasket is leaking as well. Could that possibly be a contributor? Or would that typically cause all cylinders to misfire and not just one?
The valve cover gasket is leaking as well. Could that possibly be a contributor?
Only if it was leaking enough to saturate an ignition coil.