Slowcrash_101

You only need 130psi to have combustion, granted it will be garbage combustion with a lot of unburned hydrocarbons, and a fuel injector that's going crazy.

duffsr

Thanks for the feedback. Hopeful it is still in the valves and not the rings like you said. I used the loaner autozone compression kit and wasn't wot, i've no idea if that has any impact on the readings. Leakdown test should tell more.

I don't see the car having noticeable misfire like no combustion in the cylinder. We will see what the leakdown looks like. Thanks

windhund116

But, wouldn't too lean mixture which is causing pre-ignition cause a CEL to be thrown? No matter what the cause of the mis-firing? You think that he drove the car with this CEL on, long enough to fry the exhaust valves?

Didn't the OP get a new injector ---> No CEL. Then, got same CEL later, with the new injector.

Slowcrash_101

lean mixture wouldn't really cause pre-ignition, a badly firing cylinder could as the unburned hydrocarbons coat the piston and create hot spots that can spontaneously ignite gasoline.

windhund116

I thought lean mixture was one of the primary causes of pre-ignition or detonation.

Along with, too low octane gas, too high compression, improper timing, & too hot rated spark plugs.

The plot thickens...

s2000Junky

If a cylinder isn't getting the appropriate amount of fuel per air, because in the OP case the injector wasn't delivering properly, then the combustion temps in that cylinder raise and you can then have a melt down of either to exhaust valves typically, the seats and or pistons. Detonation is a common symptom of high cylinder temps, but not always the symptom that causes the damage first, just adds to it. Its a short self destructing trip once there is a lack of fuel.

When I hear of a comp reading of 110, and a known failed injector on that cylinder, then I naturally conclude with the available information so far that some melt down has occurred, either through the valves or the pistons as mentioned. Fixing the injector on that cylinder and still having a misfire trigger again helps confirm the physical damage has been done. Now we need to figure out with a leak down test where the damage has occurred. I hope its just the head. That is not fun or cheap, but its a lot cheaper then a engine pull and replace.

Slowcrash_101

Sometimes it's easier to pull the engine, because then you don't have to remove the intake manifold.

s2000Junky

Ive done both and neither are fun, but i think it would be quicker and less evasive to just pull the manifold and keep the block in the car. Not by much, but id rather stay above the car then be under it. Pulling the motor presents a whole different level of preparation and tools/help required.

jkelley

Jordan pulled my head and intake manifold off together. I assume that would be the easiest way lol.

duffsr

Quick update, I will be doing the leakdown test Wednesday, will post up what results I find. Thanks, Reid