lol @ vlad saying plugs and wires dont cause random misfire! LOLLLLl
A random misfire code can be set on newer vehicles with OBD II onboard diagnostics when multiple misfires occur randomly in multiple cylinders. The cause is typically a vacuum leak in the intake manifold, throttle body or vacuum plumbing, a defective Exhaust Gas Recirculation (EGR) valve that is leaking exhaust into the intake manifold, or even bad gasoline. Less common causes include bad spark plug wires, worn or fouled spark plugs, a weak ignition coil, dirty fuel injectors, low fuel pressure, or weak valve springs. If a misfire is occurring in only one or two cylinders, you will usually find a misfire code for that specific cylinder rather than a random misfire code.
http://www.random-misfire.com/
I don’t see wires mentioned, and plugs is listed as a less common cause.
A bad plug or wire will lead to a specific cylinder misfire not a random multiple. How would one bad wire cause RANDOM CYLINDERS to misfire??
I’m not ruling it out entirely as wierder shit has happened, but it’s def not the most likely cause for that code.
a lean cylinder causes a miss ,coumpeter sees that it is missing,sets missfire code. a large vacuum leak leans all the cylinders in no particular order so the computer sees random multiple missfires so it sets p0300. no idle unless you hold accelartor down can be caused by a large vacuum leak like a brake booster hose. in 15 years of working on vehicals i have seen it more than once never seen plugs and wires make it not idle and surge like he described.not saying that it is what is wronge but one of the many possabilitys and probably the easiest and cheapest to check first. sill could be plugs and wires to.
I dont think thats true and if it is, thats cars bought from a car auction somehow like paying a friend with a dealers license a couple bucks to get a car… I thought that was only 3 cars though. Im ALMOST positive that theres no amount of cars privately purchased per yr that one can buy and sell…
If you ARE right… then im in big trouble as I buy more then 6 cars a yr that I personally drive lol… I get tired of cars real quick.
Well, I got the verdict today and cylinder 4’s compression was very low and the truck needs a drivers side head. Bought head for $100, will be done tomm… Did not anticipate the truck needing a head as it drives so perfect but I got it cheap enough to where I cant complain…
Cool, thanks for the update.
Try the plugs first though, fixes everything apparently :tongue
thats uncommon as hell , esp with a random code . there will be more into im sure . esp seein as it set a random . not a cyl 4 mis
vlad , your not gonna sway my thought . ya think its odd that 90% of this forum p/m,s me or calls me on shit because i am wrong lolol . keep thinkin your right and lookin up what some dumb ass behind a computer wrote up :thumbup. its guys like u and so on that call me at inspection time when the problem still aint fixed and thru every other part at it but what it needed cause some stunad behind a comp said it wasnt possible
Agree to disagree on this
:hug
Its 6 cars per year.
Just to fuel the fire, John was right about my distro being bad after looking at it for two seconds. Just sayin’ lol
ive seen many o2 sensor codes also with random misfire, changed o2 sensor and it went away
edit : oh yea this john seems pretty knowledgeable when it comes to vehicles
depending on what o2 there codes for . downstream ones have no bearing at all on fuel mixture
Indeed, they just tell you that you’re killing trees because of your cat efficiency.
John, I love you (no homo) and you know your shit, but don’t take me for a run of the mill advance parts guy, I’ve done my fair share of troubleshooting over the years and going above and beyond to get to the bottom of wierd issues.
I don’t know it all, and I won’t claim that by any means but I know enough to have a good discussion and or argument.
Are you guys gonna kiss already?
I cant tell you how many “multiple misfire” issues I have had the resulted in bad plugs, wires or distributor cap/rotor or coil packs.
almost always for me.
Well the random misfire will cause bad plugs eventually and can easily be caused by rotor/cap or coil.
I still fail to see how a bad plug or wire will cause other cylinders to miss at random.
My friend used to buy salvage cars with his parent’s dealer license and put the paperwork in his name so he didnt have to warranty the cars and sold way more than 6 in one year. Sometimes it was more than 6 in a month. He never got in any kind of trouble.
:thumbup :thumbup
depends on the make of vehicle. Take older GMs for example, even if only one cylinder is missing you get a P0300 (random multicylinder). Thats just the way they are programmed the software doesn’t isolate the cylinder with an issue for you. Only way to tell is to go in a watch the misfire data while driving it.