P0300 ,

[Searay45db]

For MAF cleaner, read the directions...carefully or you will be buying another one. Second, take carb cleaner, shoot it at the gaskets, if they are leaking you will know. It's a PITA elimination project.

 

[BeenChevy]

When are you getting the random misfire code? Startup? Car wash? Down the highway? Etcetera

 

[Fleetgeo]

When are you getting the random misfire code? Startup? Car wash? Down the highway? Etcetera

It intermittent it happen numerous of times one week it'll drive like a dream then the next week it'll give me problems it'll start up fine once it idles for about a minute you'll hear the misfired from outside you can hear the exhaust sounds like a muscle car when it idles like that when you raise the Rpms it goes away and smooothes out when you let off it shakes real violent and when you put it in gear it gets worse and shuts off if you let off the gas

 

[95escahoe]

It intermittent it happen numerous of times one week it'll drive like a dream then the next week it'll give me problems it'll start up fine once it idles for about a minute you'll hear the misfired from outside you can hear the exhaust sounds like a muscle car when it idles like that when you raise the Rpms it goes away and smooothes out when you let off it shakes real violent and when you put it in gear it gets worse and shuts off if you let off the gas

Cleaning the MAF didn't help?


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[BeenChevy]

I'd put $$ on that being the intake manifold gasket. Let us know what you find out. Maybe i can put my $$ where my mouth is *bling bling.. but i bet I'm right

 

[95escahoe]

I'd put $$ on that being the intake manifold gasket. Let us know what you find out. Maybe i can put my $$ where my mouth is *bling bling.. but i bet I'm right

X2 on that been saying it all along had the exact same issue the OP is having and that's what it was


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[BeenChevy]

Likewise. For me it happened when i let a shop struggle to replace my spark plugs on the Yukon years ago. I remember they had trouble with #5 and thought they fixed it by adding silicone. Soon as the temp dropped below 30F on the nuts it would start funky and hesitate like a ***** then smooth out. SES sometimes wouldn't trigger, other times it would flash and go out, sometimes remain lit for several start cycles. It would also be affected going through the dryer at my local car wash which lead me to beleive it was a cracked coil or something getting wet but nope - intake manifold gasket around plug 5 was responsible and replacement resolved. Let us know though.. Obviously others have been down this road replacing all sorts of parts to chase this.

 

[95escahoe]

Likewise. For me it happened when i let a shop struggle to replace my spark plugs on the Yukon years ago. I remember they had trouble with #5 and thought they fixed it by adding silicone. Soon as the temp dropped below 30F on the nuts it would start funky and hesitate like a ***** then smooth out. SES sometimes wouldn't trigger, other times it would flash and go out, sometimes remain lit for several start cycles. It would also be affected going through the dryer at my local car wash which lead me to beleive it was a cracked coil or something getting wet but nope - intake manifold gasket around plug 5 was responsible and replacement resolved. Let us know though.. Obviously others have been down this road replacing all sorts of parts to chase this.

Had a similar issue mine had the rough idle so I figured I'd do plugs & wires, did them started it up the check engine light would just flash and flash after a few mins it went off but when u started it up it ran real rough till it warmed up, then just would be rough stopped did the intake gaskets, knock sensors and runs mint now


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[Fleetgeo]

How much does it cost so get that intake manifold job done ? Is it a job or task I can take on my own or should I let a shop do it . I just ordered a new maf off rock auto and I ordered a ac delco alternator bought a brand new battery and new coils will install all of it Friday if probelm still persist I'll try spraying carb cleaner around the intake gaskets and see if that's the problem motor only has 80,000 miles

 

[95escahoe]

How much does it cost so get that intake manifold job done ? Is it a job or task I can take on my own or should I let a shop do it . I just ordered a new maf off rock auto and I ordered a ac delco alternator bought a brand new battery and new coils will install all of it Friday if probelm still persist I'll try spraying carb cleaner around the intake gaskets and see if that's the problem motor only has 80,000 miles

If you got all the tools you can do it, there's plenty of vids on YouTube for it, you'll need the intake gaskets, (2) knock sensors, knock sensor harness, valley cover gasket and valve covers if you have any leaks from either, I had the shop do mine cause it was the middle of winter paid around $600ish


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