How To Fix P0300 Random Misfire Codes In Your Car

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James Zivny: Random misfire can be more involved but you nailed the most common, good video

Jesse Godoy: love this guy, thanks for the good advice 🖒

Charles Roberts: Hey Scotty had a random misfire on my c are and found you info thanks for putting it out there

LEROY HILEMAN: scott, 2002 solara 2.2. code 300, 301 302 303 304 , new spark plugs. one new coil. new fuel filter. sprayed carb cleaner around intake, neg results inspected vacume lines cleaned maf removed maf code, rough idle let engine warm up, hold it at high rpm 3500-4000, short time engine rpm falls off unable to maintain it above 2500., on the road car has a hard time pulling out with power, once rolling feathering the pedal can get it up to 45-50 mph put in neutral car will rev over 4k put back in drive it stumbles.

uruiamnot: Ok, these symptoms say little to me, but to a pro, they are going to give you an idea.
2005 Trailblazer, 4.2L Vortec.
1. I got an exhaust leak that I can hear. It started one day twos months ago and since then, I can hear the engine more like a 1980s truck. Sound is from engine area. I have not located the exhaust leak or know if it's at a gasket or header or what.
2. Random misfires. The code is not confirmed, but I checked it on an OBD scanner and the code was pending P0300. I cleared it, and it came back pending. Cleared it a 2nd time, it hasn't come back.
3. Very rough idle at times... maybe especially when starting it on a hot day.
4. Moderate rough idle most of the time.
5. Rare, but I do see the quick Check Engine Light flash on climbing a hill sometimes.
6. I have replaced 2 or 3 COP modules over the last 2 years as I would find a P030X code and a cylinder's coil went bad. Of course, those situations would start intermittent, then finally set a P0302 code or whatever, and I would immediately replace the #2 coil when that happened.
7. It's never really idled too great, especially summer and with A/C running.
8. I have owned it with 180,000 to 220,000 miles.

I just started it a few minutes ago. No code, moderate rough idle, no check engine light, but I did not drive it far.

Noel Hernandez: I have the random missfire on my 2002 GMC sierra 4.3. I replaced distributor rotor, cap, spark plugs and wires and it still has the issue. is there something I'm missing?

santiago ochoa: you made my year Sir thank you for all this information you are providing, cant thank you enough  a million likes to your video if I could

Sione Vaka: I have a nissan pulsar 2001 N16 with Engine Light permanently on. I took to mechanic to read the codes and it was P0355 and it displays crankshaft position sensor. I then went ahead and replace both the camshaft and crankshaft sensors. The light goes off but after e few drives around on the same day, the light comes back on. Also the RPM needle is not steady during idle and they contribute to the same problem...appreciate your help...thanks

john villafana: I have a p0300 code. I am stumped. 2001 dodge Dakota 3.9l. I changed my distributor and pick up coil (no camshaft sensor). Code went away for a week and came back. Then changed fuel injectors as truck has 200k. Needed to take throttle body off to get fuel rail off and cleaned all sensors (map, idler air, TPS). Replaced throttle body gasket. Code went away and came back. Also, changed the crankshaft sensor as well. Help!!!

New York Joe: Hey ...need a tip. 2011 Durango 3.6. Just paid dealer to replaced sensors, P000A, P0017, P00455. Now less than 500 miles getting P0131, P0300, and P0171... going to new shop..They all want to start with a tune up and a coil. I'm not too certain actually very skeptical. I think it is something completely different. Any tips outside of vacuum leaks and spray carburetor cleaner. I think it may be a quick fix from a sloppy job or triggered from the sensors? What do you think, trying to save 600?

Jason Bell: The PO300 code with 'check engine' light on solid, not blinking, means that the computer is shutting the motor down to preserve the engine, as designed to. Probably to avert gasoline fire. In modern vehicles, even over 10 years old, if a spark plug or c.o.p. fails, the computer, through OBD-II diagnosis, will specify the very cylinder affected. So a V-6, with a bad pkug or coil, will run as a V-5 while sputtering and shaking but will still run. A PO300 means the problem(s) is common every cylinder, which means electronic or analog fuel/air issue. There's probably a fuel leak or fuel starvation. Often times it's the fuel pump has packed it in. And this can ascertained with difficult startups. The engine won't start. Battery fine, fully fueled, starter motor fine,

Sometimes it's a bad ASD relay, the auto shutdown that's a fire prevention system that shuts the engine if detects a potential fuel fire issue.

It could be a clogged manifold, or dirty air filter. Almost never a bad plug or coil.

If the engine runs rough after startup with check engine light on solid and quits, it could mean insufficient gas pressure. Could also mean blocked injectors. The fuel pump could be toast and/or injectors or the cylinders aren't getting enough air. Or there could be a ground fault somewhere.

The PO300 code, as identified by a handheld OBD, can mean a bunch of different things that the computer isn't designed to specifically identify. That's the frustrating thing about these vehicle computer systems. But odds are it's an analog issue. The computer isn't sensing the expected fuel/air mixture and it goes berserk. All the engine misfire shakes are by a computer system operating in digital panic mode.

Matthew Perez: got a 2000 vw jetta with 155,000 miles and I notice after I hit 80mph sometimes, the check engine light comes on and I start losing power slowly. I'm starting to have a feeling I might have to replace a vacuum hose that connects next to the oil cap to b4 the manifold. and possibly clean the manifold itself. my oil tend to get real hot and vapor.

somebodysendme: Thanks, I'm having this annoying ass code with my truck, have a few more things to try now. This video was fun and I laughed when you opened the tailgate

rich randall: I have a 1999 astro van with 4.3 vortec v 6 have most everything new, good fuel pressure,no vacuum leaks, changed fuel injector's, pressure regulator, runs great on flat will open right up, except when i go up hills when i give it lot of gas i'm getting a hesitation under load, sometimes engine light comes on p0300 random misfire? any answers what it could be??

SuperSlaiyanGod: OR, a bad coil pack/packs, spark plug wire/wires, bad fuel injector/injectors, ignition control module (ICM,) or crank position sensor (CPS.) This wasn't very thorough or accurate. Now it's better.

wholeNwon: The battery comment was right on! My car had a random rich start (flooding) condition that was severe and mysterious. It disabled the car. Clue was the that stability control light stayed on a 2 sec. longer than it should on those occasions when it did start. Tech was very smart and went to the battery first. Sure enough, that was it!!! Now I watch the batteries very carefully and plan replacement at 3 years unless it's still perfect.

Arturo Erickson: Nice touch, autozone spark gap tool. AZ!

Larry C Overton Jr: I changed spark plugs cylinder wires all way put contact grease protects from getting moisture on them. Does help

James Zivny: I've been caught a few times by problems caused by a flaky battery, now I usually check it early to be sure. Good tip.

ThatGuyWhoFeeds: I have a nissan spec v 04, replaced the spark plugs and one coil pack have a slice in the intake rubber pipe? could that really cause the engine to sound that bad

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