Error Code PO300 Random/Multiple misfire

[revhigh]

Hi All,

Any idea what would cause error code PO300 - Random/Multiple cylinder misfire detected.

Car runs fine ... starts and idles pefectly .... no change in performance. Light came on, National Auto read the code and cleared it, and upon restarting, it lit up the CEL immediately. I've searched and read about this issue here on the forum.

Spark plugs look perfect, like they've just recently been changed. I found the EGR valve, and it looks like a real B**** to get to, although I'm sure I can accomplish it. Looks like you need to remove the tube from the air filter box to the intake to access it. The plug wires look almost brand new as well, so either this car was extremely well maintained, or the previous owner replaced all that stuff because it was giving him problems. I'm looking at cleaning the EGR as a first step, then moving to the coils as the next step. We've driven the car about 500 miles since we got it, so it's not like we took it home and it immediately occurred. Just looked at this stuff tonight, but it's dark, so I'm going to wait until tommorrow in the light to jump on the EGR cleaning.

DOes anyone here know if an electrical check can be done on the coils ?? Or have the specs that they should be at ?

Any ideas ??

Thank You

REV

 

[Spiced MSP]

I had this same code a while back and I replaced spark plugs, cleaned EGR valve, replaced MAF sensor, used fuel treatment, checked for vacuum leaks, tested my wastegate actuator, and it still has this problem. Finally, I replaced my coilpacks and wires and the problem was fixed and still driving strong today. Try the coilpacks and see if that works.

 

[revhigh]

Thanks Spiced. That's exactly what I was going to do ... the coilpacks, after I cleaned the EGR, since doing that is FREE ! I took the car back to National auto today, because I just had 'a feeling' that the previous person didn't really delete the PO300 code yesterday, and it turned out that they hadn't pressed the ENTER key to truly delete the error code. So, the car didn't REALLY immediately trigger the PO300 as soon as I started it up again, as I originally thought. When I started it up after the code was REALLY deleted, it didn't trigger the error at all.

If it pops up again, I'm going to do the coilpacks and see what happens. I have no doubt that the code WILL come back, but I've recorded the mileage and date of the occurrances and will keep up with it.

Thanks !

REV

 

[Spiced MSP]

any time!!!

 

[revhigh]

Update !!

I had the CEL reset and it was fine for about 200 miles, at which time it came back on again. I was at this point resigned to getting 2 new coils. About a day or two later the CEL went OFF all by itself.

Does anyone have any idea what is going on with this thing ? The car has always run just fine. I DO believe it's an actual error rather than a short in the light or something like that, since it DID set the PO300 code. Why would it 'reset' itself without me doing anything to resolve the matter ?

Thanks

REV