i need help guys, i have a 96 s10 blazer 2wd. It has the 4.3 in it. i was getting around 320 miles to a tank then one night all of a sudden i started getting 115! I had the codes pulled and it said all the O2 sensors were bad and it had a random miss fire. i changed all the oxygen sensors, the MAP sensor, the fuel pressure regulator, and cleaned the injectors, throttle body, and MAF sensor. Now i know that my cat converter is bad, exhaust man told me that. i have a new one to go on this week. After all that i've already done it is no better. when we pulled the injectors out the tubes going to them we a lil melted. we cleaned the whole thing and the top of the intake with carb cleaner. I have no clue what else to do. If anyone has any ideas please help.

 

A misfire could be caused by an ignition issue such as worn out spark plugs/wires etc.... Have you checked that? That could also be the cause of a catalytic converter failure.

 

If you cat is plugged that explains the fuel mileage. I agree on the miss fire plugs or wires. I had a year old set of NAPA wires burn the end off the #1 plug. I fixed that & my miss fire ended. I think the best wires for the money are AutoZone.

 

thanks guys. What bout the EGR valve? someone said to check that. i know nothing about motors. lol i

 

The scanner will give you a code if the EGR isn't working properly.

 

I am experiencing something very similar to this. Scanner gave me a P0420 code, bad catalytic converter, or 02/H02 sensors, so I will try replacing sensors first.

I'm also experiencing the random misfiring, mainly when I'm idling at a stop light or sign. There is a faint "zapping" sound when the misfire occurs, which leads me to believe it's something to do with plugs, but I changed my plugs 2 months ago... I could also use some help.

 

Hey Cody,
Did you change the plug wires as well?

 

My husband's s-10 had a similar issue, he changed his plug wire and it helped. Good luck to you!

 

@1998MSO & BlazerLT2001

I did not change my wires when I changed my plugs. I will give that a shot. Thank you both.

 

I've been doing a little more research today and read that a blown Fuel Pressure Regulator could cause all of the symptoms we are experiencing. Replacing that might be worth a shot too. I'm going to try it.