Purge Valve
- Thread starter knucklehead_vol
- Start date
P0440. I think the purge valve is stuck open and when it gets hot is causing the P0301 and P0308 to misfire.
I'd be blown away if minuscule volume of air the EVAP system allows to bleed could cause a misfire.
Well this apparently happens...
"the o2 code was from the same bank as my cylinder misfire code and pre catalytic. i'm assuming that whatever mixture that was causing my cylinder misfire was starting to foul out one of my new o2 sensors, so i knew i had to act fast.
next i purchased the purge valve (50$ hyundai dealer. part #28910-22040 for a 98-05 sonata) and the gas cap 8$ and installed them both. the hyundai purge valve fit perfectly, but i think next time i'll go with the oem gas cap. now i don't have the leash on my cap anymore, so i'll probably be loosing that soon enough.
it's been 2 months now with no ses lights. i replaced both the gas cap and purge valve at the same time, so sorry i dont' have an exact conclusion, but my guess would be that my purge valve was the culprit. if my purge valve was in fact stuck open, that would explain all of my other codes addressed in the first post. basically i had exhaust fumes dumping into my intake."
Edit: whoever you are quoting confuses EGR and purge valve. The latter has nothing to do with exhaust fumes. But this person is not alone - half the links on Amazon call this 28910-22040 shiznit EGR canister purge valve.
The constant in my misfires is the p0440. I don't have bad valves. New spark plugs, wires, coil, etc.
http://www.buzzle.com/articles/identifying-the-symptoms-of-a-bad-purge-valve.html
Any other suggestions as to what could cause my misfires at random plugs?
Any other suggestions as to what could cause my misfires at random plugs?
... or choke or otherwise disable EVAP (e.g., by loosening the gas cap). The EVAP codes will pop up very quickly; but if misfire codes also pop up, the cause is different.
i know from experience the p0440 is 99% of the time the purge valve. i'm aware of the hyndai trick, but i always stick with oem stuff. when it happened to me, i changed it and the thermostat and my gas mileage almost doubled. now, under 10,000 miles ago, i had the heads rebuilt, new plugs, etc. not long ago, i started getting random misfires on 2 cylinders that went away after engine warmed up. I thought i was doing my engine a solid favor by using long life coolant (red stuff, dex cool and the like). a month ago, my lower hose assembly sprouted a leak, so i replaced the whole assembly down there, and after reading from another post about not using red coolant, i flushed the crap out of the system and changed back to good ole green coolant. my 2000 disco has never been happier and no longer misfires or acts up when the weather temp goes from 70 to 20 degrees anymore. which i'm sure you're experiencing. just my 2 cents. if you are using the red, get it out. NAPA now sells pentosin products and has green coolant with the organic anti-corrosion technology in it and that's the stuff LR says to use. Also, make sure no vacuum leaks or un metered air is being sucked in, causing lean or rich conditions where misfires can occur. good luck.
I just got the new purge valve and so far so good. Also changed the spark plugs. Before I did all this is usedone seafoam to clean out the upper intake and fuel system. I use the green fluid too. Changed all the hoses last year along with the thermostat.
Okay well the purge valve code was fixed. But I still had a misfire. Turns out the throttle heater plate was leaking a bit into the #1 plug wire. Heater plate is fixed and misfire gone.
be prepared to dump your oil within minutes of it being in there. Seafoam thins the oil to water viscosity, way too thin for the engine. I have used it for a cleaning but literally fired the truck up with it in the oil, shut it down, and then dumped the oil.
who knows. I didnt have any issues at the time, I did it as routine years back. I didnt drop the pan to see if it cleared sludge.
seafoam through the intake makes more sense for a cleaning.
changing oil and using good oil is the best thing you can do.