how do you go about diagnosing a very very very random misfire? its weird. i started my car up about 2 weeks ago and as soon as i took my foot off the brake it died. i thougth i just did something wrong, but then it wouldnt start. so once i got it started, it sound like it was backfiring thru the intake almost. a very low thunking sound, and the rpms fluctuated from 300-800. also, very randomly the CEL light would turn on the dash, but as soon as the engine it would smooth out it would turn off. so i looked under the hood, the fuel pressure gauge remained constant so i’m leanin towards it being an electrical problem. i turned the car off and tried to run a scanner on it, but since the CEL was so random, it had nothing saved. so i pulled the plugs, they look fine. then i checked the wires and pulled the cap off. the inside of the cap was very very dirty, so i cleaned it up. then i reset the ecu, fired right up and no problems since…until today. just randomly at a red light it did all of the exact same stuff. then it just stopped, then it quit running while i was driving. once i started it back up, all was fine tho. i’m not real sure where to begin, the plugs, wires, cap, rotor, fuel filter(altho i dont think its a fuel problem from wat the gauge was reading) are all less than a year old…maybe 10K miles on them. how do i go about diagnosing such a random problem like this?
mass air flow/mass air meter would do it?
i’m not an import guy, I dont know if your engine even has one of those, but I figured it was worth a shot.
The fact that the car shut off while running sounds exactly like a failing alternator (possibly loose connections)
I am also concerned about the fact that the inside of the distributor cap was dirty. Mine never even get dusty inside, clean as can be. The lack of stored/latent codes leads me to believe nothing is wrong sensor-wise.
i checked the connections of the alternator, and my vafc(dunno how acurate) remainded at 14.4v until the car started to sputter and die. im not real sure what would cause the build up of crap the in the cap tho? especailly since there is less than 10K on it? it was like a film of black soot lookin stuff almost.
i always thought that a alternator with no load was supposed to be only like 13.5 and with a load like 14
take it to advanced and have them test the charging system
an alternator goin bad wouldnt cause backfiring and CELs tho i dont think
especially since its only quit runnin on my while driving twice now. i hate chasing electrical problems
Dizzy
when the internal coil on my civic went it did all the exact same things… very, very speratic.
i dont really know how to check it other than just buying a new internal coil and seeing if it works. i think its only in the neighborhood of 40 bucks so it might be worth a try before you go trying to replace the whole distributor.
That might explain all the crap in your dist cap. All that junk floating around clogging up the contact will stop if from running.
i hope its not the dizzy, i had the original one go bad, only firing on 3 cylinders. i got a used one with like 60K on it, i suppose it is worth lookin into to see if its just the internal coil. that can be replaced without doin the whole dizzy right?
ya, not a complicated fix at all. no more difficult than changing a cap and rotor… which you may want to try also.
usually if a dizzy dies, it wont fire back up. i cant say i have seen an intermitant distributor problem. the coil itself–maybe. but i would think it would maybe misfire on one cylinder, not just shut off on all of them. usually a red dust inside the cap is the distributor bearing showing signs of it being on its way out. when it finally shits the bed, you wont have anything.
i have also seen the rotor screw come loose before and the distrubutor not fire when it should. but being you ran the car again, i would say this is not your case.
i asked at the advanced here at school about the black/gray dust i had built up on the inside of my cap. he said thats just normal electrical wear or by product. i said, only after 10K miles tho. and he said yeah its normal. is it really?
no, more original dizzy had almost no dust at all and it had 80K on it. My new one has about 10K and it and it is clean inside. I;m sure some dust more than others, but I never had that on either mine or my wife’s cars.
don’t ask a parts store guy car questions. Ask a mechanic a question, get the exact part info, and repeat it to the parts guy.
why would “dust” collect inside a cap? it shouldnt, or you would be interfering w/ the contact points of the rotor to cap. usually dust buildup inside the dist. is signs of 2 things-- it is usually a reddish/brown color when the bearing is on way out. black dust is usually when there is plastic to plastic contact-- i.e. black rotor to black cap.
thats been my experience w/ pretty much every honda distributor. im sure there are other problems/ideals though.
yeah def. no red dust yet…
If the dust inside looks like rust, you have a problem, sounds like you have a coil or igniter going bad, both are cheap and easy installs.
coil is cheap, ignitor doesnt look to be real cheap at all. im gonna repalce the coil as soon as i get my car back
didnt replace the coil yet but…
a new twist to the plot. i got the damn car to actually store the codes tonite. i was drivin all of the sudden i hear backfiring and she quit running. here was the weird part tho. when she quit running, the vafc said i had like 55% throttle…but my foot wasnt on the pedal and the car wasnt running. and while it was misfiring, the throttle percentage kept goin up on the vafc and the kpa pressure went into the positive zone(like it was forced inducted) even when the car wasnt running. but anyways, i couldnt get her started again. good fuel pressure, sounded like no spark. heres the codes she thru
14 IAC valve
41 - primary o2 sensor
65 secondadry o2 sensor
so after recordin the codes, i pulled the fuse to reset the ecu and magic…she runs perfect again