P0300 Misfire in all cylinders 2001 Tahoe

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Nicolai8775

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Now I
You might do yourself well by replacing the can and crank sensors and make sure all wiring is intact. make sure when you plug wiring back in that the wire stays encased in the connector tab and does not push out of the connector.
Now why would I not get a code if these were malfunctioning?? I just don't like throwing parts and money at it at this point. Summit suggested o2 sensors but those aren't cheap.

Should I get thicker plug wires? I'm guessing I got the cheapest plug wire oreillys had, wasn't thinking about it.

Here is something else I've noticed, not sure if it's relevant. It only misfires at idle. Or at least torque is not logging any misfires under load. It also starts and idles great for maybe 30 seconds and THEN starts misfiring.
 
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Nicolai8775

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I believe that it could be related to the injectors. What rpm does it idle at?
Well I fiddled with the set screw on the throttle body. I'm running stock TB with an adapter for now because the 92mm TB I had gave me TPS codes. So before it would jump around between 640 and 740. Now it's around 800-850.
 

Mike Shockey

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On 01 the oil pressure and cam sensor are close to each other. Your truck will run with cam sensor not reading. It is just for reference that it and crank are reading tdc together. May run fine may not. With out getting that code I would think it's fine. You can run without a guide on your timing chain. I run them because heavy springs stretch a chain a little faster and the guide helps with chain deflection. If you put the gears on wrong you would know it would spin alot before it started or be hard to start. Next time just line them up together. Cam at 6 crank at 12. It makes it super easy. And because your not stabing a distributor it doesn't matter. 58 lbs is what you need to run the injector correctly.theres a 5 lb. + or - in there. Your pressure is fine. Your pump is fine you don't need a bigger one.
I like to play mechanic with a simple rule. You've heard of kiss( keep it simple stupid). If you have a miss fire look at your plugs not black look at wires if there no factory spec or better change them. Cheap autozone might work on hei not ls. They might even work on stock ls. Just not performance get the delco or 8.8 or 10mm. Non of them are that expensive and way easier then digging back in to motor.
Good luck
 

ks03

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Vacuum gauge?

How are your fuel trims at idle, and just above when it’s not missing? O2s showing anything unusual?

do you have a fuel pressure regulator that could be dumping through the vacuum line?
 
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