I have a 2000 Accord with 3.0 VTEC engine. I am getting a misfire on #1 cylinder. I have replaced 3 of the coils now after testing them for spark. It was also blowing ignition coil fuses in the car. I done the unplug test on each cylinder and only getting this one that is causing problems still.

The thing I am coming up with is the coil is getting really hot when the car has run for a very short time. The other coils are not getting hot like this. I put a older working coil in it when I replaced the others and then when I pulled it after the fuses started blowing it had a yellow gunk on the part that goes down in the head. I cleaned out the hole and put another coil in and after driving it home where I could work on it the replacement has the yellow gunk on it as well. I popped the cover off the coil and none of the sealant in there seems to be melted but that is what the gunk looks like it is. I bought a new coil to put in and still getting the misfire on that cylinder.

I have checked voltages to the wires on the plug and get 6 volts to each of them except the trigger wire. When the car is running I get less than 1 volt to the trigger(not sure what it should be).

Oh I also removed the intake and cleaned out the EGR passage and cleaned the EGR valve because someone else told me this was the problem at first.


I am at a loss where or what to check next on this. Any suggestions or ideas?

 

Yellow gunk may have been a dielectric grease. Verify there is no oil leaking into the tube.
If the bad coil has been replaced and the fuses are no longer blowing. I would check that the valves are properly adjusted. If they lack proper clearance the valves may not fully close and loss of compression will cause a misfire. Verify spark plugs are bit excessively worn and gaped properly.

 

There is no when I pull the coil wires from that one cylinder. I replaced the coil and checked the plugs with no change.

Would valve clearance just change suddenly? It was running perfect sitting at a light then started missing.

 

If the clearance was too tight it would eventually cause a misfire, it would not be 'sudden' there will just be a point where the valve is no longer sealing due to wear.
I would suggest verifying the clearance is correct.

 

I would check the ground circuit for that coil. Sounds like a weak ground...causing high current draw...and therefor, blown fuses and high heat.

 

You may have a short to ground but not fully. Check for continuity to ground on the positive side going to the coil. There should obviously be no continuity whatsoever.

 

Here is what done since last check in.

Changed coil out with known good = No change.
Reran ground= no change
Added ground to engine block = no change
Checked voltages on 2 firing cylinders vs the one bad

Holding plug with the retaining clip on right here is the readings I got on good

- terminal in each 0 volts 25 volts and 13 volts
+terminal in each 25 volts 0 volts and 0 volts
Same readings on each

Readings on non firing #1 cylinder
- terminal 0 volts 25 volts 14 volts
+ terminal 25 volts 0 volts and 10 volts

the 10 volts is a white wire with blue stripe. I am trying to look up a wiring diagram for that model

I bumped the engine to make sure the trigger wasn't activated on that cylinder and putting power to the coil on that cylinder and got the same readings.

Next step is pull the intake and get the entire wire harness out from that side so I can trace back to where voltage is getting in that wire?

Any suggestions on right or wrong way I am doing?

 

One of the nifty things about OBD-II is if a misfire is occuring, the PCM can pull the fuel and ignition. In the case of a burnt valve the PCM can effectively shut down that cylinders coil and injector to prevent washing down the cylinder and pouring raw fuel into the converter. Which would cause a meltdown of the catalyst.

If the PCM in the 3.0 is capable of doing this, with the code set your normal diagnostics may not work as the PCM has turned off the injector and coilpack.

Have you tried swapping plugs to see if the misfire follows the plug? Rare, but spark plugs do fail. This could also be a cause of the yellow goo, plug may not be mechanically sealing and oil/fuel it getting pushed past the plug.

And I would still check that the valves are adjusted correctly, no point in doing all this work if you are not positive on the mechanical condition of the engine. At the very least to a compression check on that cylinder.

 

I already checked the plug and replaced it just to make sure. The coil pack will not spark from that connection but will on others. The wire for the trigger is showing a constant voltage on it no matter if the car is running or just powered on. I bypassed the entire section of the wiring harness from the main bundle that comes off to the connector when it wasn't showing continuity. I get continuity this way but still showing voltage to that wire 100% if the time.

Let me tell you it is a SHOCKING experience to pick up the coil where it was out so I could check for spark when I touched the plug. There is no spark showing on the plug but when I grounded myself on the engine block I had a lot of spark myself.

The reason I am being persistent on the wires and stuff is because I have done all the switching of coils, plugs wires you name it and this connector is the only one having a problem.

Compression test done showing in green on my gauge. The yellow goo looked like the stuff in the coil that they sealed the top off with. The PCM hasn't shut down the injectors for that cylinder yet. I am getting tons of raw fuel smell when it runs coming from the exhaust.

 

This might sound stupid, but my daughter's step dad had been pulling fuses to put in the ignition one when it blew the first couple and pulled one from Cruise control. I was doing the ELD checklist because when I rescanned I got a p1298 code and possible causes are bad ELD or ECM. ELD is a lot cheaper to fix so was checking it first. One of the first checks involves cruise fuse. Fuse was missing and when I replaced it the miss disappeared.