PO300 Diagnosing a Misfire- 2003 Chevy Silverado 5.3L

The truck would barely run, only code that came up was the PO300 Random Misfire
Here are the links I mentioned

[brawdo]

Never thought to look at an injector that way. Thank you gonna try with my laser thermometer

[arthurgay]

So far I have watched at least a dozen different videos about a PO300 misfire code on a later model Chevy Silverado and I saw a dozen different problems that have caused it. The 5.3 in my 05 Sierra is now in the metal bin and a 307 from a 1972 Chevelle, with a set of 202 heads and a camshaft from a mercruiser marine engine is sitting in its place hooked up to a 700R4 transmission. No more misfire code !!!

[JoeCnNd]

Dude you may be a life saver. I totally spaced the catalytic converter being a problem.

[moc]

What a great idea... the IR detector. I have one and will be trying it on my own misfire problem. I can add that you can get those things for something like $15. I use mine for cooking. You can also check for heat leaks from your house--- if you find a portion of an exterior wall or of a ceiling below the attic, the inside of which is colder than other wall or ceiling panels, then maybe it needs better insulation.

[edgorman]

Make sure the PCV system is functioning correctly. These engines are noted for Ring issues.

[nv]

Good process, but I've learned to avoid crap Chinese aftermarket parts whenever possible. They seem to get worse every year.

[fastdadgarage-northsouthch]

I hope this helps someone. Sorry I called the Temperature Gun a heat gun, hope that wasn’t confusing. How do you start your diagnosis?

[dioad]

Awesome video my man totally forgot to check manifold temp. we use to spray water on the manifold.

[samueldenton]

The build up in the injector is a wax like film the gas leaves after sitting in the cold to long I think

[brotherslawnsnow]

Straight to the point. Thank you very much.

[markrandall]

That goo looks like excessive fuel stabilizer. If you use that make sure you mix per manufacturer instructions.

[slofouru]

Pretty crazy the ecu isn't smart enough to determine which cylinder is misfiring, especially with injectors that clogged. The cars I usually work on can narrow it down to individual cylinders pretty accurately. P0300 should only code if they are all misfiring, but apparently chevrolet believes any number of cylinders counts as "random" 😅

[kevinbennett]

Mine just started doing this once it started getting cold . Once I need a smog of course

[chrischambers]

So I did just like how you did with The digital thermometer. My truck was all running for about a minute or 2 and the exhaust manipuled. To get app to like 770°, and then got up to a 1000° But yes, having the same problem. So I'm pretty sure that is a sign of my Cadillac converters are clogged.

[jmartin]

Great video! Thanks, tons of info in a short time!🌈

[shannonc.]

12 volts will open them up & a little tape around your straw will make it tight enough to see a spray pattern. You can back flush them also using this method. Be careful of sparks and flammables!

[jamesperkns]

Thanks for the video hope that's what's up with my 2004 5.3

[leejenkins]

Mine says"p0300 misfire#3 cylinder, replaced the plug, wire and coil, and it still says misfire, so it's got to be the injector.

[ssh]

Thanks ! That is a clever way of diagnosing the P0300.

[patrickbaca]

Would a bad purge valve thrw a misfire code aswell with the evap code cause that’s my problem right now