Hey guys got one for ya, i have a 95 blazer 4.3 that has been running a little rough the past couple weeks. Finally this morning the check engine light came on and was flashing at me. pulled the codes this evening and got, ignition module fail, misfire cylinder 4, knock sensor fail, and O2 sensor no activity. The First 2 i can see being connected to each other problem wise, but the second two throw me off, friend of mine said it could possibly be the computer. Any thoughts suggestions??????

thanks in advance for any input.

More info; i did have a vacuum leak for good while, "before this issue" found it at the Hvac switch and was able to get it to seal when the switch is set to off, i also had trouble starting bout a month ago and checked the spark at the coil and it was a yellow color not white or blue. I have been noticing the volt gauge reads pretty low almost looks like 12 volts but i checked voltage at the battery and it read 13 and went up when turning on accessories.

 

Sure it could, but i doubt it.
I would get a wiring diagram, and sit at the dining room table and study it. Trace all the wires on paper, try to figure out if any wires are common to each other. The computer gets blamed alot when its really something else giving the computer crap information. GOOD LUCK!

 

Think i got it figured out, i cleared the codes and ran to see what came back and only one came back misfire 4. Pulled the plug and it some deposits on it so im going to look into a new set, I had the alternator checked and it passed, put it back in the blazer and is now showing 14 plus volts go figure. I did clean the connections up a little bit after install so hopefully the low voltage problem is now fixed just got to get a set of plugs.