Dead Injector

[Yell04]

I've been getting an intermittant miss lately and wasn't sure what was going on. Last night on my way home, it turned into a dead miss. I belive I've lost the fuel injector on this cylinder but want some input from folks with more experience than me.

My AFR appears to be unaffected and this is why I belive it's the injector. Is this solid reasoning or is this not really a good indication? If it was the COP rather than the injector, is there a good way to determine that? Do injectors or COPs sometimes fail gradually or do they usually just fail outright and is there something else I should be checking?

Thanks in advance for any help you can provide.

 

[patman0911]

With the engine idling, take a really long screwdriver and press it against the fuel injector and put your ear to it and you should hear a distinct clicking sound as the injector opens & closes. If one of them is quiet then you've found your dead injector.

Are you getting any codes?

I can't quite predict what the results of a dead injector vs dead COP would have on the A/F ratio but I think in both cases the O2 sensor would read lean since either way there'd be way too much unconsumed O2 and that's what it senses, and the computer will increase the fuel trims on that side to try and compensate. You'll need to pull the plugs and see what they look like - I think the three good cylinders will eventually get fouled but the bad one will either be dry if the injector is bad or wet with fuel if the COP is bad.

Check everything out thoroughly before you jump to any conclusions though. Make sure all the connections on the COPS and injectors are seated well, make sure the COPs are firmly on the plugs, make sure there's no moisture in the spark plug wells and that the COPs don't have any cracks or signs of arcing, pull the plugs and look for any obvious signs.