Hey everybody, got a 99 blazer 4.3 which i love. Lemme tell you what its doing: about 3 days ago it started up fine, ran around town for about 3 hours, then it just started sputtering and not running right. Stalls and tries to die when rpms are low, like when shifting from park to drive(or reverse). Ok what ive done so far: replaced sparkplugs, wires, cap and rotor, and distributor(plus cam position sensor). Still runs awful-no change in its behavior. Oh and ive straight-piped in lieu of my cat out of necessity. Ideas? Suggestions? Im stuck and very frustrated! PLEASE HELP!!!

 

P0300 is almost always caused by a fault in secondary ignition: plugs, wires, distributor cap, rotor and ignition coil. It can also be caused by low fuel pressure and incorrect camshaft retard.

These engines are very fussy when it comes to ignition parts, especially with plugs, (AC Delco 41-993 gap .060") and distributor cap, (AC Delco). If the distributor has been removed, camshaft retard needs to be checked, and probably adjusted.

List all of the DTC's, (diagnostic trouble codes) in the order they were retrieved.

 

Ok, theres an o2 sensor code thats been there since i bought it 3 years ago. The guy i bought it from said its been like that ever since he put flowmasters on it. so theres that, and the random misfire code, i dont know the number, but its there. So list in order is : oxygen sensor, random misfire, oxygen sensor, random misfire

 

It makes a difference what the oxygen sensor code is. If it's for the downstream sensor, it will have no affect on engine performance. If it's for an upstream sensor it will make a difference in how the engine performs and could possibly set the random misfire DTC as well. We really need to know the exact DTC's before continuing with the diagnosis.

 

Ok so the guy at AutoZone was being #@&!ing jerk and wouldn't hook it up to get the codes, he said he didnt think the o2 sensor would cause it to sputter and stall like it is and that its probably a fuel injector cause thats a common problem in those "fo-threes" and tried to sell me some for only 350 bucks(which i dont have). So ima run it up there tomorrow and get somebody worth a crap to diag it. Any ither suggestions?

 

Sounds familiar.... AZ, Advance & O'Reilly will all check DTC's for free, try another store. The point of DIY is to diagnose it properly BEFORE spending money.