[John Clark]

In order to see any misfire counters you need a factory capable scan tool. Most global OBDII readers will not give you enough info.

As for misfire detection, the computer monitors the cam and crank signals and looks for instant slow-downs as the crank sensor goes past each cylinder's firing sequence. They are not always accurate but have gotten better over the years. \

My guess is you might be able to see the injector problem using a current measurement with a scope but Honda puts many different items on the same circuit as the injectors so you have to sort through all kinds of other "noise" on the scope waveform. Without a graphing meter or scope you're stuck with pulling injectors and swapping them to see if the problem moves to another cylinder. Have you checked compression? Even if you don't have a compression gauge or scope you can check compression just with your ear during a crank sequence. Pull your coil fuse or injector fuse or fuel pump fuse and then just crank the engine and listen to it. It should sound even on every cylinder's compression. If you hear reh-reh-reh-reh-reeh-reh-reh then you have a compression issue. If they all sound even then it's possible to still have a compression issue but most likely not.

 

[John Clark]

For full features on Honda the Foxwell NT510 is probably the best scan tool for the money (under $200.) It does global OBDII on any vehicle and will do full bidirectional factory data on the vehicle make you purchase it for. You can add other makes for $60 each, up to 5, I think. A few here have purchased it based on my recommendation and I don't think anyone has been disappointed. Amazon has them...just make sure you buy one with no make installed or Honda preinstalled.

 

[John Clark]

Here's a thread going on right now where there is a compression issue and it's easy to spot with a trained ear during the crank:


http://www.odyclub.com/forums/9-pro...s/9-problems-concerns/310105-starting-issues-after-timing-belt-replacement.html

 

[John Clark]

The clean intake runner for cylinder #4 has been bothering me for the last couple of days too, but I can't put my finger on why it would be clean. The deposits are due to the PCV system putting the crankcase air back into the intake manifold. Fuel does wash carbon buildup but the deposits are prior to the injector, aren't they? When I pulled my upper intake manifold to do the valve adjustment I found all 6 lower intake ports dirty. I just left them.

As a side note, I just watched a fresh diagnostic video on a Honda CRV that had a bad ground on one coil pack. This one was pretty hard failed but you could have something similar either on the injector or the coil pack.

 

[John Clark]

... You really gotta look at the car running with diagnostic tool
to inspect real time misfire counters. You maybe chasing your tail with particular cylinder misfire...

This is so true. Just because it's throwing a P0304 doesn't always guarantee the misfire is on cylinder #4. It could be the cylinder before or after it in the firing order. The firing order is 1-4-2-5-3-6 so I'd look at cylinders 1 and 2, as well, though the clean intake runner on #4 is still a clue that doesn't support this theory.

This vehicle may need someone who is good with a scope on ignition and injector pulses to see if they can track down the issue.

 

[John Clark]

So, the misfire is very evident when it occurs? Can you duplicate it while working on it? If so, simply unplug a coil pack to verify the cylinder. Then, it would be nice to know if that coil pack is firing during the misfire event and if the injector is firing during the event. Since you've moved everything around and the misfire stays that means it could be a wiring issue to either the injector or the coil. This thing needs a scope or graphing meter attached to monitor it when the misfire starts.