Ok so one day I was driving my 1996 blazer (now at 227000 miles) and had the cruise set at 70 then suddenly it died. I put it in neutral while coasting and it wouldn't crank. That problem ended up being the electronic ignition. Well I went ahead and changed the cap, rotor, plugs, and wires while I was in the fixin mood. About three weeks later I notice that while I am driving at highway speeds (60-70) the rpm's fluctuate. For example, at 70 it would go from the normal 2200 rpm then suddenly to 2500. So basically the torque converter was locking then unlocking. Well after a little while of that, it finally threw a code. The worst of them all...random cylinder misfire (i think that is P0300). The problem slowly progressed to a slight misfire whenmoderately accelerating (around 2500 rpm). Now when I am accelerating it starts to misfire at around 1800 rpm and will sit there and do that all day if Imanually hold it in gear. The only weird thing is that when it is misfiring, i can floor it and it doesn't miss at all until i let off and it goes back down to normal engine speeds. Yesterday after all that acting up that the blazer did, I got out after getting home and smelled a weird smell out of the exhaust. It wasn't exactly eggs like a bad cat is said to smell but it was a little weird smellin. Maybe it was a little eggy but that wouldn't cause a random misfire would it? Thanks for all the help

 

Today I decide to change the fuel filter (cheapest fix) and voila!!! It suddenly drives perfect with no problems the whole twenty minutes I drive it... It's fixed!!!.....WRONG!!!!![:@]
I park it and let it set about two hours. Crank it and drive down the road and it still misses at the same rpm when shifting but only did it once and the rpms didn't fluctuate as much at 70. So now it's at least bearable, but not completely fixed. Maybe it's the fuel injection? The spider assembly was from my old motor so it has about 227000 miles now. Maybe that's the problem. If anyone has any ideas, feel free to tell me. Thanks, have a good day, thank you come again.

 

Just double check the cap and rotor especially if you used a cap with brass terminals, and make sure none of the wires are touching anything sharp, or hot, where they could rub/ burn through. Also, how long has it been since you had the intake gasket replaced? I have seen where the intakes create a vacuum leak INTO the crankcase, and cause a misfire. Usually that will cause the low speed misfires. HTH.

 

never replaced the intake gasket. motor has probably 80k so I wouldn't think they would already need to be replaced. I'm beginning to think that the saying is true about gm vehicles, "they run bad longer than most cars run at all." but of course toyota runs good longer than gm runs at all

 

I, as of now still have this same problem I had in February and was wondering if anyone might have an idea on what it might be. As of now it only does this misfire when the motor is not completely warmed up. After I drive for about fifteen minutes, it will clear up. I'm pretty much getting tired of this junker. I have now replaced the intake air charge temp sensor, IAC valve, plugs and wires twice, electronic ignition, cap and rotor, fuel filter, EGR, TPS. I really need someone who might know what this problem is to chime in or else I'm gettin rid of this after winter.

 

A few weeks go by and i'm still alone in this little black box. can someone help?

 

I had the random misfire issue come up on my blazer. The mechanic told me to run fuel injector cleaner through it. I have done that and have not had the problem since. He indicated that if it came back, then he would recommend taking it and having the injectors cleaned. My plugs and wires were new at the time that it was doing this. I would suggest having your injectors cleaned.

 

That might be the problem since my injectors have about 235000 miles on them as of now. I might just buy new injectors and not even worry about the cleaning since they have so many miles.

 

ive got a 97, ive posted an issue like this already, but this is exactly how mine acts as well, with also what i have posted. i guess i really need to try the injector cleaner.

 

I have a 2000 Blazer doing the same thing. My mechanic told me needed to replace my fuel injector spider looking thing!! $900 for parts and labor.[:@]OUCH!!!