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Discussion Starter #1
I've been having a slight misfire under acceleration for a while now. I've changed out all the plugs and wires and I've seen no change. I checked all connections and all coils are reading .8 ohms which is right where they're supposed to be.

What am I missing?
 

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Discussion Starter #3
I'm sorry, I should have clarified. Under moderate acceleration the truck will start to shake slightly at about 2800-3200rpm. Under light acceleration and heavy acceleration it doesn't do it. It has never triggered a CEL, its very slight. I also notice that when I start the truck and the engine revs right when it starts, it doesn't sound smooth.
 

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Previously Micash21
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A misfire will present a code identifying what cylinder your misfire is on. Not every misfire is directly related to a spark plug or coil.
 

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I would do a compression test. If the CEL isn't being set, I would lean towards a valve issue.
 

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Previously Micash21
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When a misfire, or bad combustion occurs, the normal combustion process is interrupted, negatively affecting engine performance. So what can interrupt the combustion process? In simple terms, anything that changes a combustion parameter. Now that’s a pretty wide reaching answer, but just think about those things that can adversely affect combustion.

Pre-ignition (the beginning of combustion before the spark plug fires) certainly affects the combustion process. It results from hot spots in the combustion chamber. Also, the build-up of carbon deposits in the combustion chamber can effectively raise the compression ratio. The result is detonation, which is the igniting of the remaining air/fuel mixture ahead of the flame front. While we’re on the subject of things that can affect ignition, a bad spark plug wire (on those vehicles without coil-on-plug ignition) is a common cause of misfires. Also, a clogged fuel injector will limit fuel flow, causing a misfire.
 

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Discussion Starter #7
I forgot to add that when I pulled all the plugs they all looked normal. Also the problem is not consistent, sometimes its pretty bad, other times it's barely noticeable.

I've never really looked at an injector from a 5.7, can they be visually inspected for issues if they're removed?
 

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Previously Micash21
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You have to flow test an injector. Which means you will hook it up to a piece of equipment and it will measure the volume that the injector puts out.
 

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"You like popsicles?"
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Hate to say it but sounds like a broken valve spring. A broken spring shows the same symptoms. Pull the valve cover on the side of the motor showing the misfire and give er a peek
 

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Valdez Racing Team
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he's not throwin a misfire code..like advised earlier, have you cleaned out the throttle body (pull it out and clean both sides.)...
 

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A broke valve spring wouldn't throw a code either. There is no electrical connector for one, so there is no reading sent back to the PCM to trigger a code. It does sound like your best bet is to pull the valve covers, both sides, and check em out. Any spark related issue will trip a CEL.
 

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Discussion Starter #12
I cleaned out the throttle body about 6 months ago, I haven't cleaned it since. I'll pull it and clean it and see if that's helps. If that doesn't fix it, I'll start pulling valve covers. If at that point I do not find a broken spring I guess I would have to expect a bad valve? Is there any way to diagnose a bad valve before pulling the heads? I'd hate to pull the heads and find nothing wrong.
 

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Valdez Racing Team
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a broken valve spring should be felt at all rpm's... but wouldn't hurt to checkem to rule it out..
 
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