Hi, I have a 98 chevy 350 and it has a bad misfire. I thinks thats what it is it makes loud pinging sound when going up hill and no power. I also have a p0420 code. I noticed a Exhaust leak on drivers side not sure. would that cause it? I have new cap rotor wires plugs. thanks for any help

 

Pinging sound.... could be that you need to step up to better gas. 87 octane will "chatter" in my truck under a load so I run 93 only.

 

but with the p0420 he probably has a stopped up converter.

 

It could be a number of things, but bad gas could be the culprit. A little seafoam would be nice to clean out the motor a little bit. The code you're throwing is only for emissions. As long as you don't have a leak anywhere near the front O2 sensors you shouldn't be getting any false fueling unless it's telling the motor to richen the mixture sense the cat is being inefficient.

 

I put my money on a clogged cat converter.

 

Hi, thanks for all the replies. I took it to a muffler shop and they said they were fine. He told me that the msd 6al that I have eats up rotors, and that may be my problem. I think he mite be right the last rotor only lasted 6 months can anybody recommend a good rotor.

 

Po420 is a missfire code. Check the rotor like you said and if that don't fix it find someone who can put on a scanner and read missfire data and see what cylinder it's coming from? Could be a bad injector. The older vortecs with the spider injectors are bad about that.

 

What brand rotor are you currently running?

 

P0420 is catalyst low efficiency. P0300 is misfire