well today I replace the fuel injections, spark plug and new plug wire and was hoping that would solve my misfire as in the PO300 and guess it did not, spent over 400.00 just that. And now back to the start again all over and now got a few more ideal to check....here what it doing start right up but rough idle, lack of power, at about 1500rpm it smooth, then drop in drive feel it running like on 6 or 7 instead of 8 and smell of gas, If anyone have an ideal about let me be know, I will also keep posting here till it fix. Thank Mark

 

Make sure the plug wires are all on the correct plugs then double check again...

 

you may what to check out this list of items also
http://www.obd-codes.com/p0300

come to think of it didn't you post this already..?
if so try to stick to one post thread, you can use the "quick links" todays post to keep up with all current post....

 

Do the oxygen senor have anything to do with misfire or rough idle, I got 179,000 mile on this Tahoe 99 and that is one things that was never replace as long as I own it.........I was reading that it should be replace every 100,000 mile which I did not know and now was wonder that might fix the problem I'm having so in morning going to Auto store and get some new one........ Thank Mark

 

If they're the original ones, then it won't hurt to replace but may not solve the problem.

 

Don't seem to be needing any more help or was it..........well after everything I done so far with parts replace and all, and over look a new part that can be 1 in a million to be bad and now she purrrrrrrrrr like a kitty cat.
Thank you Mark

 

what finally fixed your problem ? was it the o2 sensor ?

thanx.

 

Old Thread, I know....


Seriously, having the same P0300 left bank misfire codes. rotor, cap, wires plugs, TB cleaning, fuel pressure to spec and still getting CEL. His purrs like a kitten and won't tell why. HAHA let me in on your little secret... electric tape over the CEL on dash?