misfire question...

Discussion in 'General Chevy & GM Tech Questions' started by reggiecab2000, Nov 14, 2013.

  1. reggiecab2000

    reggiecab2000 Epic Member 5+ Years 1000 Posts

    just another lovely misfire question for you guys...

    Ive been dealing with misfires for over 2 years now, they just never stop, but anyway ive had a steady (random misfire) at idle for over a year now, and it is easily detectable to the human ear and quick "bump" in the truck when it happens obviously.... only thing is it never throws a code! itll misfire all day while idling and never throw a code? can anyone offer insight as to why my engine does not throw a code when having these misfires? it has thrown codes before for misifiring when i needed to replace my distributor and such, but not for this...
  2. fugitive

    fugitive Member

    My first guess would be burnt out cluster bulb! But as with mis-fires like you I have been dealing with the same issue for about the same amount of time and without the drawnout troubleshooting process it could be numerous things. Have you had it on a scanner lately?
  3. reggiecab2000

    reggiecab2000 Epic Member 5+ Years 1000 Posts

    no its not a burnt cluster bulb, that works just fine, I actually have an Edge CS insight monitor and can read and clear DTC's on the fly, prior I would check with my hypertech programmer, even while its misfiring and everything it never throws a code, last time i had it checked was when Justin at blackbear performance told me it was probably due to my CMP retard being off -12 degrees or something, which i did take to a reputable shop that claims they fixed that, though it never made a difference, since then ive really just given up and dealt with it for now
  4. fugitive

    fugitive Member

    One thing that is kinda outside the box you could try is check to make sure the vent holes on the bottom of your distributor are'nt blocked preventing the ozone gasses from escaping that are created during the numerous arcing cycles of the rotor to the cap those gasses are what cause the discolor/oxidation on the contacts. It's worth a shot. Good luck I know it didn't help mine when I removed the screens but it may help yours I'm still fighting mine but the light keeps returning I have been leaning toward a lean fuel condition underload?
  5. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    Are you sure that it is a mis-fire and not a rough idle? I am pretty sure that a mis-fire would throw a code. I think over time I have gotten to know you and I am sure that you have already done some of the things I am going to suggest. I would check your IAC. maybe pull it out and clean the tip off. My 95 had a rough idle with no codes, I finally tested the iac and found it to be at the highend of the recommended spec. I changed it and the idle smoothed out almost instantly. Also, you may want to pull the egr valve and give it a good cleaning (if equipped, my 03 and 05 do not have them.) it will cost you $4 for the gasket. Also, I am sure that you have done it, but clean the MAF and throttle body well. My 02 developed a unstable idle, I ran some sea foam thru the brake booster vac line, let it sit for 20 minutes and started it up. The idle smoothed out. I am just making suggestions here. I really think that a mis-fire would be throwing a code. I am thinking it is a rough idle caused by something else.
  6. reggiecab2000

    reggiecab2000 Epic Member 5+ Years 1000 Posts

    done everything you said except the IAC and EGR, i should check those (on my third distributor lol) but i know its a misfire, because when i was sitting there with Justin doing my retune, he had his laptop hooked up and was showing me at idle that i was having multiple random misfires thats when he suggested the CMP retard. I know it is misfiring for sure....

    but in the end isnt a "rough idle" caused by misfiring???

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