2004 Accord EX-L 3.0 Misfire Saga
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Joined: Aug 2017
Posts: 7
I'm not either....and everyone (including myself) thought I was nuts replacing six coils after putting one new one in and moving it to every cylinder never stopped one of the 7 misfire codes (one each cylinder plus a random) Yet when I replaced them all, all 7 misfires disappeared. While I still have this miss or stumble whatever this is does not cause the PCM to generate a code after 1,000 miles of driving
Last edited by Red955i; Aug 17, 2017 at 10:03 PM.
Joined: Jan 2018
Posts: 1
Hi All. Like others I was getting the dreaded misfire codes for all 6 cylinders AND a random misfire. I checked for vacuum leaks, changed the plug, checked the EGR and read the live data for fuel trims etc. I was convinced it was the coils. To test I bought ONE new coil and put in Cylinder #1. Reset codes, drove and still got all 7 misfires. I moved the new coil to Cylinder #2, then 3,4,5,6 each time resetting codes. I always got the same 7 misfires. Clearly not the coils...right? So I read live data again and still thought it couldn't be anything but the coils. Bought 5 more coils, replacing them all..reset the codes and guess what? No misfire codes? WTH? Passed inspection...all is good. Except...at idle....occasionally...you will still feel a miss, or stumble like bump, bump bump. When it does this the tach is still steady. live data only shows a small 40 rpm sway in idle not shown by tach and not related to this miss or stumble. In the 2500 miles I've driven since the coils I did get a O2SB2S1 and O2SB1S2 code and replaced those two. Live data does not have car running rich or lean. Fuel trims do not expose a vacuum leak etc. Anyone care to guess what that miss or stumble is? My only guess is I have a bad or clogged injector...thanks for any ideas
i have that same little bump at idle. My valves are pretty loud though so I’m going to try replacing all my coils because I have that same misfire issue, and then adjusting valves. Hoping that brings a smooth idle. Keep me updated if you find a solution!
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Joined: Aug 2012
Posts: 3,070
From: Southern New Hampshire
@nomad2020, you just replied to a post six and a half years old.
Yes, you are correct, one coil typically goes bad at a time, very-very rarely two might go. The bizarre thing is when scanning codes these motors will typically report bad coils all over the map when one goes bad. The only reliable way to test for which coil has bone bad is to disconnect one after the next, listen for a change in engine speed, reconnect it and move on to the next. When you disconnecting the bad coil it will not impact engine speed and you've found the one which needs to be replaced.
Yes, you are correct, one coil typically goes bad at a time, very-very rarely two might go. The bizarre thing is when scanning codes these motors will typically report bad coils all over the map when one goes bad. The only reliable way to test for which coil has bone bad is to disconnect one after the next, listen for a change in engine speed, reconnect it and move on to the next. When you disconnecting the bad coil it will not impact engine speed and you've found the one which needs to be replaced.
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