2000 Accord EX V6 misfiring

2000 Accord EX V6, 133K
I'm having trouble tracking down the cause of some ECM codes I'm
getting. Here's the story so far...

On the way home from work the other day, engine started running rough
and check engine light came on. Being an hour from home with a Honda
dealer just up the street, I stopped in and figured they could help me
determine what suddenly went wrong. They could (for $85! - what
pals!).

I had them hook up to diagnostics and came back with codes 0302 and
0306 indicating misfires in these cylinders. The tech determined that
I needed plugs (I have 133K on the car). He also did a 'coil swap
test' and that the ignition coils in cylinder 2 and 6 failed as well.
They wanted an additional $340 to change out spark plugs and the 2
coils. I thought that was pretty steep (including the $85 for diag, I
was looking at 425 - no thanks)

I did some research and decided on iridium plugs. I also purchased 2
ignition coils from Autozone. I installed the plugs myself (I didn't
gap, as several sources on internet said that was not necessary with
these plugs). I then installed the 2 ignition coils in cylinders 2 and
6 (from a ignition firing diagram at autozone, they said cyl 2 was the
middle rear and cyl 6 was right front as you're facing the engine. I
disconnected the negative lead from the batt and waited 10 minutes to
reset the ECM. I reconnected and started up expecting it to purr...
Still running rough! About one minute later, check engine light comes
back on.

I take it to autozone this time for the FREE diag (I'm getting
smarter), and I get back codes 0300, 0305, 0306. For some reason, cyl
5 now has a problem, cyl 6 still has a problem and I'm not sure what
0300 indicates.

I'm already $275 into this just on parts and would appreciate some
info on what might be happening.

 

Assuming your errors are P03xx (the "P" means powertrain), P0300 means a
random misfire (any cylinder). The other codes are misfires for specific
cylinders.

A misfire DTC is not necessarily a spark issue (and often isn't).

Replacing coils is NOT a good idea, and is certainly NOT a substitute
for proper diagnosis.

Misfires can also be caused by lean mixtures. such as may be caused by
intake leaks or clogged EGR ports.

Some vehicles even suffer misfire codes if the battery has been
disconnected and the idle-learn procedure hasn't subsequently been done.

A bad throttle position sensor or crank position sensor can also cause
misfire DTCs.

Have your dealer look up the Feb '02 issue of Honda Service News. There
is an article in there involving your exact problem. Dealers are
supposed to keep a binder with all the HSN publications in it.

Somebody needs to do a proper diagnosis on this car with a proper OBD-II
code reader that is capable of advanced reporting.

 

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Somebody pissed in your gas tank. I've had similar codes when I stopped
suddenly at a traffic light. The Honda had been in storage all winter
and there was lots of water in the gas tank. A can of injector cleaner
and some gas line antifreeze fixed it up right away.

'Curly'