Honda Car Forum

Thanks Tegger. I've seen your FAQ in the past, so appreciate the fact
that you know your stuff. The bottom line is that there appears to be
more potential causes than I can deal with as a layman. I was just
going off what seemed to be black and white on the diagnostics info I
got from the Honda dealer - and I quote:

"pulled codes P0302 and P0306 for misfires in cylinders 2 and 6.
Pulled spark plugs and found all plugs to be very worn. Also performed
balance test and found the number 6 and number 2 coils to fail. Needs
spark plugs and coils number 2 and 6, EST = $340".

So to me sounded pretty cut and dried - new plugs and replace coils 2
and 6 - and all things I could do myself for way less $. I was pretty
proud of myself until I started my car and it still ran like shit.

I'm reluctant to bring it to that Honda dealer, as they've raided my
wallet every time I've had an issue. I have a local mechanic I trust
more that I will present with some of the information you noted and
see what happens. I'll post back when the mystery is solved.

"Butcher" <urabutcher@yahoo.com> wrote in news:1176492336.780507.222610
@b75g2000hsg.googlegroups.com:

> Thanks Tegger. I've seen your FAQ in the past, so appreciate the fact
> that you know your stuff. The bottom line is that there appears to be
> more potential causes than I can deal with as a layman.



There sure are. Engine systems tend to be interconnected, whether on
purpose or not. I don't pretend to be an expert on this.



> I was just
> going off what seemed to be black and white on the diagnostics info I
> got from the Honda dealer - and I quote:
>
> "pulled codes P0302 and P0306 for misfires in cylinders 2 and 6.
> Pulled spark plugs and found all plugs to be very worn.



Worn-open gaps will cause the coils to fire at a higher-than-normal
voltage, which has a tendency to chew up the insulation. This eventually
leads to shorts to ground through the coil body (before the plug gap).

This is plausible, but, I think, unlikely.



> Also performed
> balance test and found the number 6 and number 2 coils to fail.



Hmm. I wonder what the tech actually did. Did he do "freeze-frames"
using the Honda HIM tester? Did he check any other values, such as fuel
trim?



> Needs
> spark plugs and coils number 2 and 6, EST = $340".



Except that now you're getting a P0300, meaning the ECM can't tie the
"misfire" down to any particular cylinder. This means a global problem
with engine management, and not likely anything to do with the ignition
at all.

See below...


>
> So to me sounded pretty cut and dried - new plugs and replace coils 2
> and 6 - and all things I could do myself for way less $. I was pretty
> proud of myself until I started my car and it still ran like shit.



The problem is one of unfortunate terminology. Unfortunate for those not
versed in the EPA's mandated automotive systems, that is.

"Misfire", as a term, has nothing whatever to do with the spark. All it
has to do with is the ECM not seeing the crankshaft speed up like it
should after a spark event.

Your engine has a firing impulse every 1/3 of a revolution. The ECM
expects that the crankshaft will speed up and then slow down with each
firing impulse, following a particular pattern. All the firing impulses
should make the crank speed up and slow down the same way (within a
range). If some of the impulses result in LESS of a speedup than
expected, the ECM interprets this to mean the mixture has failed to
combust correctly and sets the P030x DTC.

The failed combustion can be anything from incorrect mixture to a stuck-
open valve to failed coils and a number of other problems (as I outlined
in an earlier message).

See here for a good professional explanation of misfires:
http://www.aa1car.com/library/misfire.htm



>
> I'm reluctant to bring it to that Honda dealer, as they've raided my
> wallet every time I've had an issue. I have a local mechanic I trust
> more that I will present with some of the information you noted and
> see what happens. I'll post back when the mystery is solved.
>
>


Please do.


--
Tegger

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

>
> Please do.
>
> --
> Tegger
>
> The Unofficial Honda/Acura FAQwww.tegger.com/hondafaq/

So I figured out the reason that replacing the 2 failed coils didn't
fix the problem. User error - I put one of the new coils in the wrong
cylinder! Took it back to Honda and after talking to the mechanic, he
corrected me on how the ignition firing order is laid on on the V6's.
Once I got home, I swapped out the coil I now knew was bad with one of
the ones I had originally taken out. I got lucky in that I picked the
good one, and the car started running right. Reset the check engine
light (pull negative lead off of battery) and the things running like
a top again.

As a treat, I filled her up with some Shell VPower and will throw in a
new PCV and air filter this weekend (with an oil change about a month
away).

Thanks again for the info. I have your FAQ bookmarked - some very
useful information up there.

Butcher <urabutcher@yahoo.com> wrote in news:1176815948.370558.308960
@d57g2000hsg.googlegroups.com:

>
> So I figured out the reason that replacing the 2 failed coils didn't
> fix the problem. User error - I put one of the new coils in the wrong
> cylinder! Took it back to Honda and after talking to the mechanic, he
> corrected me on how the ignition firing order is laid on on the V6's.
> Once I got home, I swapped out the coil I now knew was bad with one of
> the ones I had originally taken out. I got lucky in that I picked the
> good one, and the car started running right. Reset the check engine
> light (pull negative lead off of battery) and the things running like
> a top again.



Huh. So in your case it appears to have actually been a spark misfire. Will
wonders never cease.

Glad it's fixed, anyway.





--
Tegger

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/