Ok so my brother gave me his 1996 blazer with a 4.3. It was messed up and he owed me money he couldnt pay so the deal was i fix it and i can keep it. When i got it, it sounded like a real bad misfire. So what i did was buy spark plugs, wires distributor cap and rotor, changed oil and filter, changed tranny fluid and filter, and air filter. It ran perfectly fine until i got to town. Cruising down a state road at constant steady speed was fine. The stop and go traffic is what messed it up. Im pretty sure it just keeps fouling out my plugs. They were put in less than 50 miles ago and are NGK Platinums. Checked gapping and checked the order of plug wires to make sure but its running like crap again. Acts like 2 cylinders are dead. And no engine codes or check engine light is on. Oil pressure is around 60. It has about half a quart too much in the engine if that has anything to do with a higher oil pressure. And temp stays around 140-160 and doesnt heat up past that everAny ideas???

 

any engine codes? how old are the wires distributor cap and rotors? might be worth replacing them? A/C delco only for these parts as the 4.3 is very particular coming to these parts anything else they tend to run like crap

 

Plugs, wires, cap and rotor are all brand new. No engine codes are being given

 

If the SES light is on - the PCM will have stored a code. This is not clear in your first post. SES light on or off when running? Does SES light come on when key is on and engine is stopped (does it work at all)?

If the engine is misfiring, the SES light should be on from the misfire detection system catching the misfire and a code should be set. If the misfire detection system is malfunctioning that will also turn on the SES light and set a code. Simply how the system works. So something is not adding up.

Only thing that would make sense is if the SES light has been disconnected and you are not really checking for codes.

 

new member in need oh help. I have a 95 blazer vin w 4.3. bought it with new pump installed and only 30 lbs at rail. I tracked it down to regulator being weak. replaced issue solved starts and idles great... when cold. as soon as it starts to warm up it goes to crap idle up and down huge miss and runs so rich it will burn your eyes and nose. I have replaced plug wires cap rotor and fuel filter as well as did a vacuum test. only today it showed codes of 33 map high voltage and 45 I believe is o2 lean. I have cleaned iac as well as egr with no change. what else could it be as this is my first 4.3. thanks in advace for your thoughts and input, micah

another thing is it doesn't always do this at idle. it is a come and go thing it does when sitting there. maybe five minutes good running out of every 15 sitting at idle. when it does show its but it sucks really hard threw the intake.