azmark30

iTrader: (4)

my car CES light is blinking and Im getting - po300 code (random misfire)

I replaced all the spark plugs and check the coil packs but didnt see any blistering on any of them.. Does anyone know how to test for a bad coil pack?

thanks for any help -

KPierson

iTrader: (1)

When I had a bad coil pack I got specific cylinder misfire codes (ie po3001 - cylinder 1 misfire). If you have multiple bad coils you may get a random cylinder misfire, but thats hard to tell.

What all is done to the car? What EM are you using?

G350ZTT

How much do this coils usually cost? I have the cyl 1 missfire and multiple missfire code.

azmark30

iTrader: (4)

i have a vortech on it with the split sec..
Coil packs are 80 dollars at autozone..
Im going to take it in tomorrow and have it scoped..for 90 dollars..

monkiee

I have a similar issue. I'm getting a P0306 (cylinder 6 misfire) code. If I clear it, it will come back after a few starts. The misfire is quite obvious at idle (I can hear it - the engine "hiccups" every once in a while). But as soon as I start driving, the motor feels/sounds smooth.

KPierson: Did your motor feel different when you had the misfire in cylinder 1?

(I have a 2003 350Z with a Greddy TT kit on... running UTEC.)

mw9

iTrader: (51)

any updates

monkiee

I've been a little distracted and haven't spent much time troubleshooting this. (I bought a motorbike.) The car has been on the road for ~9 months with this issue (misfire in cyl#6).

Hopefully, I'll have some time to troubleshoot over the next couple months. I figure it's either the coil, wire, or sparkplug. If anyone else has any ideas, please post!!!

track1z

iTrader: (4)

Guys before you go spend X amount of cash on a expensive coil pack.Swap out that coil pack with another cylinder.If the problom go's to that cylinder you know thats the problom.If it stays the same probable spark plug or more seroius!

davidz33

iTrader: (7)

is there a possibility that the engine suffers misfire without showing CES light if the misfire timing is within a tolerance (I don't even know if there is a such thing as tolerance, but my car has a "small random hiccups" during idling).

Hoooper

iTrader: (5)

a p0300 can be the result of a bad MAF sensor, O2's going bad, or several other issues, do some searching into this, you can find a few more things

CLETUS

yes. every engine misfires pretty much all the time. since the o2 sensors are only looking at data from 4 cylinders ( i4 or v8) 6 (i6 or v12) or 3 (v6) the a/f ration changes constantly. you can see this as the o2 sensors bouncing back and forth from rich to lean. since the a/f is read and altered by bank, not by individual cylinders (think top fuel) they are always just a bit off. if i plug in a scanner at work and let a car idle it will throw a misfire every once in awhile. this is normal. the pcm has a logic program or algorithym to detect a cylinder that is missing more than it should.

KPierson

iTrader: (1)

Arn't misfires detected by the crank angle sensor? I've never heard of using an O2 sensor to detect a misfire.

Hoooper

iTrader: (5)

neither have i, however i have heard of bad O2 sensors CAUSING a misfire

mestisoZ

iTrader: (5)

hmm. i got a misfire about 2 days after i installed my test pipes?.... maybe bad o2 sensor before i got checking the coilpacks? i ono im confused. just wanna get rid of the cough at idle. any help would be cool thanks

EmWhyr0hEn

It rare for a coil pack to go bad. You need to get your self an FSM and a multimeter to properly check them though.

seeya

iTrader: (3)

Not on our engines apparently. I just replaced 2 in the last month. I was told by both shops that I got them from that they sell a ton of coil packs to G35 and 350z owners. One shop suggested that it was due to moisture getting in and causing the spark plug to arc?

ddc665350ztt

checking your coil packs would probably be easier. if there's no cel light i dont think its that much of an issue. an 02 sensor might cost more. or maybe you just need a good tuneup.

FirepowerZ

I saw this post after looking for problems similar to my 350z. My CEL is on and have had it scanned 3 times getting the code PO350 primary and secondary coil failure but the car is running smooth and goes like a beast, no abnormal miss fires or loss of power. I also did a manual reset 3 times and the CEL light seems to come on randomly when it likes. The last time it took a week before it came on otherwise sometimes it will come on after a few starts. Been doing some research and apparently coil packs generally dont go bad and shouldnt be changed untill it pretty much dies and the car stops going? Apparently it can be a problem with the main module, sensors or a short somewhere..Dont know if this information helps anyone here but thats what ive gathered up till now

Lawn Dart

iTrader: (4)

I had this same problem last year. It turned out to be a faulty fuel injector.

https://my350z.com/forum/maintenance...o300-code.html

Derek1167

I had this happen back in August. Replaced the pack and it happened again to the same pack a month later. This was less than 500 miles. I drive my car less than 3,000 miles per year. This past weekend I fired her up and the symptoms were back. Granted the last two were replaced under warranty, but it was less than 1400 miles and two brand new packs went bad. They were all on cylinder 1.

After the garage fixed it a second code was thrown and I had a bad coil pack on cylinder 3. Seems like a shitty reoccuring problem. In fact I have been considering trading in my Z just because of it. It has cost be over $300 and is annoying.

car info: 03 Enthusiast Manual with 61K.

I hear now this is common in the Z, G, Maxima, Audi, and Volks