P0300 flashing at me

Scholzyyy · January 18, 2018

Ok so my check engine light started flashing at me when ever I go between 75-85mph on my 2006 2500hd 6.0 GMC Sierra. so got a dtc reader and it gave me p0300 so I did some research and came up with random/multiple misfire. So I replaced the spark plugs the spark plug wires and the ignition coils and that still didn’t do it so after spending about 4 hours more on research all I can find is conflicting result. The closest thing I can find is that someone said they had to replace there vacuum lines. I’m hoping it’s as simple as that but just wondering what you guys think. I would just keep replacing stuff like the coils and spark plugs but the parts arnt getting cheaper as I go along. Any suggestions would be greatly appreciated thanks!

Formulabruce · January 18, 2018

Remove the air box, and make sure the filter and the "gauge" are clean and working. then remove the throttle and completely clean with throttle cleaner. Clean it very well including the plate. This area Must be spotless for the air flow meter and temp to work right.

make sure you use throttle body cleaner and not carb cleaners. reset and test. good luck

Scholzyyy · January 18, 2018

I recently put a cold air intake on the truck and fogged the throttle body and it didn’t really help but I will try going through the throttle body a little more throughly and see if that does anything. Thanks

davester · January 18, 2018

Try cleaning the MAF sensor and switching back to the stock intake. The CAI does nothing for the truck, other than make it sound louder...

Raptordude · January 19, 2018

Try having a crank/cam re-learn performed. You need a capable scanner and then it takes about 15 seconds, so don't let a shop over charge you for it (I got mine done for free)

Over time the cam chain stretches and the readings are thrown off. At high speeds it can misfire. The re learn let's the computer compensate for the stretching cam chain

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