LowZ33

Hey guys.

So about two weeks ago, I was driving down the street in my Z, and there was a street bike next to me. He revved at me, I revved at him, we went about our ways.

I parked my car for about two hours, got back to it, and when it started up it sounded kinda weird. I took a quick look, dismissed it as me being paranoid, and got in and started driving. As I was driving down the street, my car began bogging down and losing power.

I pulled over to a gas station, messed with it for a bit. Checked my battery, intake, etc. Noticed I was throwing a code. (Did not have a code reader at the time)

Got the car home, and on the drive home the SES light began flashing. By the time I had gotten home, the light had turned off altogether.

I'm assuming it was misfiring, because of the research I had done, flashing SES light = P0300, random misfire.

I replaced all 6 spark plugs, and when I got to cylinder 5, it was full of oil. So I pulled the coil pack, dried everything off, soaked up the oil, replaced the spark plug, put the coil pack back in, and plugged everything in. Still misfiring. (Yes I know my valve seal is bad, that's in my to-do list, just need the car running first).

So I figured since the cylinder 5 coil pack took an oil bath, it was toast. Went out, got a brand new coil pack, and put it in. Still misfiring, although now it won't stay running either, and while it's cranking there's some apparent smoke coming from behind the motor. I checked and made sure, and my coil plug for cylinder 4 and 6 are not mixed up, since I heard that was a common mistake.

Any ideas? I need to get this car back on the road, I'm horribly sick of driving my civic.

Thanks in advance.

EDIT: It's a DE, by the way. 04

rllynch1

Just googling P0300 brings up quite a few options for what the code could be - anything as simple as the plugs (which you've already replaced), to as bad as a leaking head gasket.
https://www.yourmechanic.com/article...-jamahl-walker

It's easy to just start throwing money at what you think is the problem but, as you've found, it doesn't always solve it. Take a look through that list. Find the sensors, and while the car is running, unplug them and replug them and see if it makes a difference. If it doesn't, you may have found your problem. It's better to start with a free diagnosis than to just dump a bunch of cash into it and still not find the issue.

CFS_Z

smoke can just be a leak ( water or oil )
id try doing a compression test.
make sure your getting spark to that cylinder aswell as fuel.

PerfZ

iTrader: (3)

Tough to diagnose when it won't stay running but,pull the connections to the coil packs 1 at a time just to make sure it truly is #5 - start with that one. Make sure all other connections are correct, and good - it seems beyond coincidental that the problem got worse after the spark plug change.

ishyne22

iTrader: (3)

Camshaft position sensor back of engine probably the one near cylinder 5. Change it. Change them both for that matter as well as ckp. They crap the bed. Problem fixed. If not check maf.

ishyne22

iTrader: (3)

99% sure these will fix your issue. If you need asap autozone stocks them usually.

https://www.ebay.com/itm/162034713534

LowZ33

I'm gonna go ahead and spring for these. Thanks for the heads-up!

AARONHL

iTrader: (1)

My SES flashes when my oil is real low

Arrtus

I recommend investing in some higher quality sensors if you're going to be ordering off ebay. If you're paying $8 for each sensor, how good of a sensor will that be?

LowZ33

I'll be buying Duralast ones retail, not directly the ones he linked, haha.

PerfZ

iTrader: (3)

Either of those sensors will throw a code, and it will tell you which CPS is bad. Nor will it cause a random misfire, in my expeeriecne anyway and I have had one fail. No sense spending $180 on the two CPS sensors and whatever on the crank sensor for no good reason. They didn't just happen to fail and they don't cause your indicated problem.

LowZ33

It was initially throwing a code, then stopped on the drive home. I'm not sure why.

PerfZ

iTrader: (3)

Yes for random misfire which is not typically a symptom of a bad sensor in my experience. I had a bad CPS and it made the car hard to start when warm, not cold, but it ran fine. It did throw the code for the actual sensor though and I replaced it - $80 and 20 minutes. I have had some bad coil packs - had a bad ground which I believe caused it several times in rapid succession and the SES light did flash sometimes, but stayed on fully when not flashing. Code was random misfire. What I find strange with yours is that the problem got worse after you worked on it. Not insulting but that generally indicates operator error. Check ALL of your connections - some are a bit hidden and I know I have missed hooking something back up correctly after having it apart. 2003, owned since new, 157,000 miles with a few bolt ons, all installed by me. Not always correctly the first time lol.

LowZ33

Yeah, I know what you mean. I'm probably going to re-check everything when I go to work on it again. I really want to get it back on the road, it's killing me lol.

RobPhoboS

Have a look at my thread, see if that's any use:

https://my350z.com/forum/maintenance...0-misfire.html

I doubt it'll be the CPS (for the reason above), and definitely don't anyone use a cheap ebay one (my car stalled at a junction and wouldn't fire up for 5 mins hah).

Try the in-line spark tool like I show on the thread if you've used contact cleaner on the MAF already and done the plugs.

LowZ33

Update:

I'm ordering new (higher quality) camshaft position sensors, crankshaft position sensor, and a Walbro 255LPH fuel pump. Figured it can't hurt to replace them and I've got the cash available right now. Will update once all the new parts are in.

eddiethree50z

Had that happen to my 2006 350z at one point.
Driving perfectly fine and suddenly started jerking and eventually stalled out on the side of the fwy.
I ended up taking it to the nissan dealer and had them run a diagnostic (118$)and sure enough i had a misfire on cylinder 3 and also a random misfire.
So what they did was replace the ground wiring i guess it was causing the coil packs to blister up..also spark plugs and battery.
685$ total but it ran like a champ

PerfZ

iTrader: (3)

Sounds logical. I was blowing coil packs right and left and it turned out to be a bad ground connection. Fortunately I isolated it myself and since then, not a single problem.

mattymoe

hey all new here i have 2004 de. I got the infamous Po300 code. I unplugged the maf sensor and plugged it back in and it ran fine for ten minutes,then it had a rough idle and and sputtered under load again,I repeated the process and same thing.Cleaned the MAf and now the problem is consistent. could it be a spark plug or a ignition coil,I checked coils for the blistering and couldn't find any blistering. i thought if those where bad then they are bad and the car wouldn't have an intermittent fault. Where do you suggest i go next? BUY a new MAF sensor?

mattymoe

bump?