I have a 1998 Blazer LS 4 door 2wd 4.3L 'w' code. It had a really bad misfire a couple weeks ago so i replaced the plugs and wires, runs better now, but still has a misfire when cruising, rpm doesnt seem to matter nor does speed, it also seems to stutter when shifting, the misfire causes bucking while cruising, WOT it runs great most of the time, take off runs fine too, only having problems when shifting and cruising. The fuel regulator, pump and filter were recently replaced, as were the spark plugs and wires. My dad is a master tech and one of the best in the business but he won't help me b/c it isnt his problem and he blames old age and high mileage...mostly b/c its not his problem adn he doesnt care until it breaks down, he never helps me until it gets way outta hand (last time he said it was fine and wouldnt look at it i ended up having to replace the cat b/c of misfires and vacuum leaks). Can anyone help me? I've heard injectors, regulators, wires, plugs, cam sensors, crank sensors, bent components in the valvetrain and distribitor gears worn out, i'm leaning towards the distributor.

 

If it's misfiring badly then it should have set a DTC (diagnostic trouble code) or two. They are what illuminate the SES (Service Engine Soon) light. Stop by an Autozone, etc. and have the codes read otherwise anybody would just be shooting in the dark as to a cause.

 

The SES light came on a while ago, p0300, multiple/random cylinder misfire. i cleared it and it wont come back, it is intermittent now and bucks when cruising. maybe tranny? idk, but i cant expect any help from my father unless it breaks down out of town, he claims its nothing and its b/c its 12 years old with 166k miles, yet if something were wrong with his 24 year old car with 180k+ miles it would have to be fixed, so even though he hates this kind of diag. or me listening to people he doesnt trust, it is the only way it will ever get fixed before its too late.

 

Finish the tune-up with a new distributor cap and rotor and see how it runs.

 

unfortunately i need to be relatively sure before i go replacing parts as i work part time and am a college student, not to mention i've dumped $500 into it last month on parts already, nor have i the know how to change the distributor, i dropped out of automotive classes right after 1st quarter b/c my dad wouldn't quit bitching about me studying to be a tech. Is the distributor set up the same way as the old v8s or differently? what am i looking for to determine whether it should be replaced? it stumbles intermittently during shifting now also if that helps.

 

I didn't say change the distributor, just remove and replace the cap and rotor, should cost ~$40. A tune-up is not complete without replacing these two items. If you are unsure about doing it, you should get a Haynes or Chilton service manual at most auto supply stores.

 

check the easy things that cost nothing first. for example drive to any autozone or advance auto and have them hook up a scanner under your dash for free. then go into the live data mode and watch the intial timing as the truck runs. see if the timing is steady or bouncing all over the place. and take notice if its in the negative or positive also. i had bucking when crusing under light throttle and it turned out to be that the rotor base reluctor had slipped on the shaft and retarded my timing... i had to make a custom rotor to adavnce the timing.....make sure you use AC Delco brand only for your tune up parts...

 

lol, so my dad keeps saying nothings wrong and im imagining things. well now that the check engine light came on i'd like to see him stick to his claim and continue thinking nothings wrong.

 

your probably gonna have to fix it on your own.... from what you have mentioned it sounds like he doesnt want to be bothered.....just curious, what state are you in?

 

he just doesnt want to deal with it, as usual, he'll help my brother or sister, but with me he doesnt care. i'm in texas