P0300 Random/Multiple Cylinder Misfire

osborne0915 · #1 (**permalink**) 04-27-2007, 01:48 AM

Are there any other common problems that would cause this besides the coils? (2002 2.5l)
I changed the spark plugs first and then started swapping the coils with the new one I bought. It didn't seem do get any better or worse when they were switched.
I installed a spec-v header about three weeks ago. Car ran great. Over the past week it's gradually started to chug a little at low rpm's and idle a bit rough. It's gotten progressively worse to the point now where it's pretty much missing all the time except over 4,500 rpms and then it gets better. Light also started flashing intermittently.
Are there any other tests I can run to see if there’s anything else wrong?
I just don't want to keep buying coils @ $100.00 a piece and that’s not even the problem.

I also have two other codes that I think wouldn't cause this condition:
P1564 Which I think is the cruise control
P0031 That started after the header. I think I need a bigger o2 spacer.
Thanks…

asdfasdf128 · #2 (**permalink**) 04-27-2007, 01:56 AM

i have the same code after i took off my intake manifold and header. Im gonna try getting new gaskets, but if you check out the vboard, they have a pretty good troubleshooting section.

Heres the link, not sure if you need membership to access it though:

The V Board :: Log in

osborne0915 · #3 (**permalink**) 04-27-2007, 03:38 AM

I think I was incorrect... The P0031 is for the front o2 sensor not the one I had the spacer on. I just assumed it was that since the light came on immediately after installing the header.
That would make sense since the bank 1 sensor would tell the ECU to dump more fuel, which would seem to create the condition I have now.
I wonder if it went bad since the exhaust is actually flowing properly now. My old (3rd one) precat was so clogged up the engine wouldn't turn more then 4,500 rpm's. I'll put the voltmeter on it tomorrow and see if that's definitely it.
Thanks for the link..

osborne0915 · #4 (**permalink**) 04-29-2007, 03:24 AM

Well that didn't help... Still chugging along Replaced with a universal Bosch sensor I was able to reset the light and it stayed off for a couple of starts. Once on the road the light came back on and was flashing again.
I'm going to bring it back to Autozone and get the code pulled. Hopefully it will narrow it down to what cylinder is misfiring. I tried switching the coils around again and nothing changes. I'm starting to think it's something else.
Anyone got any ideas... I feel defeated.

milktdry.com · #5 (**permalink**) 04-29-2007, 11:57 AM

You're not supposed to be driving it around if the SES/CEL is flashing.
SES/CEL 'ON' = something is wrong.
SES/CEL flashing = NOT GOOD

I had the same problem BEFORE I put my headers on.
Bogging a little, light flashing....

I am under warranty
and work at a Nissan dealer,
so the techs tried a few things.

The check list for this P0300 misfire is huge.
Many things to check and not cool for a tech
who is only getting paid warranty time (which sucks.)

We replaced the FRONT A/F ratio sensor on MY SE
and the bogging went away.
I'm still not sure that was the problem
because when I plug in the Consult II from time to time
the P0300 still shows a history.

My SES is pretty much constantly on and
I have no tuning right now (which MAY help),
but I have the Emanage Ultimate and Nismo cams poised for an install and tune.