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Old 08-13-2014, 04:01 PM   #21
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Originally Posted by Seefo View Post
How do you really know you don't have a misfire?

This looks like either an injector is not working right and dumping fuel, or you have no/little spark.

Do you have the oil from the engine? you could do an oil analysis and see if there is more fuel than normal.
1. Plug looks fine.
2. Pretty obvious when it's only hitting on 3 instead of all 4
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Old 08-13-2014, 04:02 PM   #22
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Batch fire doesn't mean all for injectors fire on every stroke. It means 2&3 fire together on the compression stroke and 1&4 fire together rather than each injector firing individually. #3 isn't going to fire on the exhaust stroke.
#2 Compression Stroke = #3 Exhaust Stroke and vice-versa.

Same for #1 and #4.
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Old 08-13-2014, 04:17 PM   #23
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Originally Posted by hornetball View Post
#2 Compression Stroke = #3 Exhaust Stroke and vice-versa.

Same for #1 and #4.
Oh, duh! Can't believe I just said what I did. So I suppose that's a possibility then.
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Old 08-13-2014, 04:19 PM   #24
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Originally Posted by guttedmiata View Post
Batch fire doesn't mean all for injectors fire on every stroke. It means 2&3 fire together on the compression stroke and 1&4 fire together rather than each injector firing individually. #3 isn't going to fire on the exhaust stroke.
Batch fire means it will fire again on number 2's intake stroke. I said cylinder 1 at first because I got confused with spark, but still.

The injectors fire twice, and once it's going to fire when it's actually the intake stroke for the other cylinder that it's sharing the injector pulse with.

2 and 3 don't fire at the same time.

EDIT: Nevermind, you just read it above.
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Old 08-14-2014, 12:15 AM   #25
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Another thing to consider, if it was an intake valve problem, and the batch fire was allowing fuel to blow through the cylinder on it's non-combustion stroke, then during the combustion stroke it would be dead lean from all the missing fuel that escaped through that nice shinny clean exhaust port. If you don't have any indications of that cylinder running lean, then I would say that this could not be your culprit.

Keith
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Old 08-14-2014, 06:22 PM   #26
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My guess is a leaking head gasket.

With a very small leak, you likely would not notice any steam. The super clean #3 exhaust port is the biggest indication to me of water passing through that cylinder.

By the time the engine is blowing great white clouds out the exhaust you have a serious problem - overheating, blowing water out the rad cap. possiby caused by a cracked head or head gasket failure that is very obvious (a clear path can be seen across the head gasket surface between one of the cylinders to a water passage).

I don't believe other suggestions like excessive gas as this will typically result in a wet plug, likely missing and lots of soot in the exhaust port. Not the case here.

Did you notice any loss of water? Also, its a little late now but for next time...
When you suspect a leaking head gasket to the water passage - BEFORE you disassemble the engine - you can try removing the rad cap on a running engine to see if there are any air bubbles appearing. In many cases, during the power stroke, there is enough pressure in the cylinder to push exhaust gas into the water passage. Easiest to see if the thermostat is open or removed. depending on how large the leak is, it may take a few minutes of idling before you see air in the water.

Good luck.
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