hey guys am new at this
i recently bought a 96 blazer and 2 days later i was driving from work and my engine light came on with the p0420 code Catalyst System Efficiency Below Threshold (Bank 1) and i also started hearing this pinging noise like if the timing was wrong but i only hear it when am driving i dont know if 1 thing's got anything to do with the other one
i know theres no way to adjust the timing on 96 blazer's and i think i have to replace the the catalytic converter but i dont know how to fix the pinging noise
am thinking maybe its got something to do with gas i started putting 87 octane thats what the manual says its recomended am really worried about that noise cause it only happens when am driving
maybe its got to the with the knock sensor or egr am not 2 familiar with this engines

please help


Nelson thanks

 

It may or not be the converter having a problem (as far as the trouble code is concerned). Could be the o2 sensors. are bad. (certainly a cheaper and easier fix than welding on a new converter) I honestly don't know how many sensors ODB II Blazers use. But as a general rule it would be at least one upstream and at least one downstream. I dont know about the pinging though. 87 octane should be fine for that truck unless you have a computer tuner in it. I'd replace the fuel filter if I were you for good measure though.

 

that code is also relative to whether or not your gas cap is tight. if your cap is loose or has gone bad the engine light will come on.

 

^^ I wouldnt really say that because I have rode with my gas cap off before ( dont ask me how lol) and I never got an check engine light come on. Maybe I am just lucky?

 

Left bank... i believethats an O2, the sensor is before that cat right? is there a sensor after the cat as well?

 

go google...

http://www.obd-codes.com/trouble_cod...old-bank-1.php

 

am not sure if theres 2 sensor i'll have to check
but am really worry about the pinging noise it doesnt sound in idle or park not even when u give it gas on park
only when am driving
i heard that it might be the egr or knock sensor they r kind of expensive
am wishing to find out what it is
my brother had a s10 and he told me he had the same noise and he never found out what it was
had anybody here had that problem before?

 

Run 89 octane and hte pinging will go away.

I had hte same problem with mine when I got it. I use 89 octane with 10% ethanol and it cleaned out my fuel injections system. Now I can run whatever I want without pinging.

the gas tank is presurrised on the newer models. If the cap hasn't been spun hard enough to click 6 times or so you may have a vacuum leak.

I would do those first, disconnect the battery negative battery calbe for 30 seconds and see what happens.

 

i also noticed that when i cranked it up the starter kind of goes slow like if its out of time
but theres no timing adjusment on 96 and newer models

 

is there anything messing up my timing cause i got a timing gun and i check it and is off a little