1999 chevy tahoe misfire code p0300

[andre912]

HI, yesterday I did a tune up on my Tahoe and after I did the plugs wires rotor cap and button ive had a misfire I took it to auto zone and they gave me a random misfire code ive never had this problem before when I bought the parts for the tune up I bought all OEM plugs and bosch wires does anybody know where this could be coming from? thanks

 

[Phone Man]

Probably the crappy bosch wires. Put the old ones back on and see if it goes away.

 

[99Vortec]

P0300 is multiple cylinders misfiring. Did you use an OEM Cap and Rotor?

Also assuming you disconnected battery for tune up, are your +/- leads tightened sufficiently.

 

[SunlitComet]

please get misfire history with proper scanner please.

 

[Gmc lovin75]

HI, yesterday I did a tune up on my Tahoe and after I did the plugs wires rotor cap and button ive had a misfire I took it to auto zone and they gave me a random misfire code ive never had this problem before when I bought the parts for the tune up I bought all OEM plugs and bosch wires does anybody know where this could be coming from? thanks

Why would you use Bosch wires when everything else was AC Delco? Pull those junk ones off and put AC Delco on and make sure all your boots are on good an snug and recheck everything you did.

 

[Gordo1728]

Also assuming you disconnected battery for tune up, are your +/- leads tightened sufficiently

Why would you disconnect the battery for a tune up? The leads are irrelevant.

I'll have to side with everyone else on the Bosch wires. If you still have a random miss, let the truck idle, spray around the edges of the intake with carb cleaner, and listen for change.

 

[drakon543]

As to the reference to disconnecting the battery for a tune up. Most vehicles it really doesn't matter too much but in some occasions it can help get better benefits of doing a full tune up. It will clear the ecm table so the engine will adjust and build a new map table with the new plugs and wires. I disconnect my battery any time i work on the engine. Tune ups included.
Back to the miss fire issue. As sunlit commented try to get us a missfire history. Outside of that ditch the bosch wires as suggested. Secondly what brand cap and rotor did you purchase? I usually read reviews and such on any parts i purchase and it seems the 5.7 vortec doesnt like certain cap and rotors.