first of all i drive a 96 chevy blazer 4.3 vortec 4wd... i have look through all the forums and have yet to find one to help me.... i was noticing a rpm drop from 1000 to around 500 for the first couple of minutes of being started and it would quit.. well one day hell came and my blazer just made a loud back fire from the engine and try to drive it, would do ok but would shake and sputter till it died well took it to the shop and the mechanic said "it was only running on four cylinders that it was crossfiring in the distubutor"
right after leaving the shop the blazer now idles at 500 rpm and tends to hesitate but run somewhat decent
well... heater core goes out and fix that... in doing all that my brother took off my rpm hand and put it back on trying to find more bolts to take the dash out well the hand was sticking when i put it all back together i was tapping pretty hard to get it loose enough to work through the glass.. well at the same time i was doing this my check engine light came on
now my blazer is back to where i started missing and sputter while driving and at idle but seems worse at driving
i have replaced the following
rotor and cap
plugs and wires
gas filter
ive cleaned throttle body with proper spray and properly cleaned my k&n filter in doing this the violently missing and shaking of my vehicle has calmed and now it just seems to sputter/hesitation while at idle/driving/ and acceleration doesnt change with heat or anything stays the same throughout driving
this has all happen over a period of 6 months
oh and the code after getting check at autozone says misfire on cylinder 1
light is still on and blinks from time to time
all i can think of is maybe a sensor or injector what ive read so please help

 

Proper diagnosis starts with all of the present & pending DTCs. Please get an accurate list of the DTCs that are present and pending then post it in this thread and we'll go from there. Autozone, Advanced Auto, and many other autoparts stores will scan for present codes for free and will list pending codes if you ask them (still free).

What brand of cap & rotor did your mechanic install? These trucks prefer AC Delco caps & rotors.

 

well i changed the used one he said he put on there to a brand new duralast cap and rotor

i also forgot to mention it used to crank up on the first turn of the key now i have to turn over like 4-6 times and it barley gets enough to start up
each turn i hold it at starting position at least 5 seconds

 

Have you done a fuel pressure test?

Duralast parts aren't known for their quality on these engines....

 

ok got that code its p0300 is what its giving me and as for the fuel pressure test i got a tester but cloudy how to do it do i just hook it up to the nipple on my gas line behind my throttle body and turn the engine on??? and if it reads right psi im good?????

now with wires, plugs,rotor, and cap the situation has improved it has gone from a violent shake of the vehicle to a sputtering/missing while idling,acceleration, and normal driving. i sort of baby the throttle afraid it might go back to the violent shaking bc i need my blazer for driving to school and work so i dont gun the throttle

 

Did you read the link I provided concerning the fuel pressure test? Yes, you hook it up to the test port then step through the procedure (or whatever parts of it you can). There are multiple criteria that will tell you if you have a problem and, if so, what the most probable cause is.

Could still be the cap/rotor... Many members have chased their tails and wasted countless dollars & hours on diagnosing a P0300 code only to find that the crappy aftermarket parts were responsible. I would return them for refund and pay the extra $$ for the AC Delco cap & rotor.

 

sorry didnt see the link well test went good considering ive read that 60 psi is good.... i read 60psi with the key turned on and it only dropped 2 psi when i cranked up the engine

 

Ok... So what were the results of the rest of the test? Did the pressure drop more than 5 psi after the pump shuts off? If that all checks out, swap out the cap & rotor for AC Delco parts.

 

well now it is reading around 52psi to 53psi hand is jumpy and it dropped exactly 5psi

 

Is that with the engine off or on? It needs to be >55psi with the key-on/engine-off and remain above 50psi for 10 minutes after the pump shuts off.