2005 Civic, 159,000mi

Got a Check Engine and the DTC was "Number 2 Cylinder Misfire" accompanied by minor engine shake. It occurs right after engine start and lasts only about a minute or less, after which it smooths out perfectly.

If I reset the code, it will out stay generally until the next day and a cold-start (though occasionally it will happen w/ a hot start as well).

My first thought was a plug or coil, so I pulled the plugs (all double platinum in great shape with perfect color), checked the gap, and swapper #2 plug into #1 cylinder (to see if the problem followed the plug, or stayed w/ the #2 cylinder).

I also swapped #2 coil into #3 cylinder, so that:

If the problem was the PLUG, the misfire would now show #1, and if the problem was the COIL, the misfire would now show in #3 cylinder.

RESULT: The misfire remained with Cylinder #2

This made me think the problem may be the injector, so I swapped #2 injector with #3 injector, thinking if it was the injector, the misfire would follow the bad one to #3.

No such luck, and the Misfire DTC Code remains #2, and the engine has the same little shake, usually after start.

In my mind, that leave wiring problems or some mechanical problem specific to #2 (compression, sticky valve, etc), but the engine is ordinarily SO smooth and there are no ticking noises even when unsmooth that I tend to doubt a mechanical problem.

Anyone with suggestions, or a similar problem that was found?

Thanks,
Bob

 

Do a compression test. Check the spark plugs.

 

Yes, I mentioned I pulled the spark plugs and checked them and swapped them as I detailed in the first write-up.

After finding the problem NOT related to spark plug, coil, and injector, the compression check is next on my list, as is the possibility of a small water leak from the head gasket into the cylinder as the engine cools off (would explain why the misfire happens after a re-start).

I should have made my posing shorter as it may have been too long for you to read through to see the details. I'll try to keep it less verbose next time. I realize most people have limited time to read all the new postings.

Bob

 

Did you look closely at the spark plugs? The color and overall condition can tell you a lot.

Rust - water
oily - burning oil

are they all the same color? Are they different?

 

Yes.

From my original post:

"so I pulled the plugs (all double platinum in great shape with perfect color), checked the gap, and swapped
#2 plug into #1 cylinder (to see if the problem followed the plug, or stayed w/ the #2 cylinder)."

Not burning oil, and the coolant looks OK.

Friend who owns this car (for whom I am trying to fix his problem) now tells me the car has overheated repeatedly.

DOH!!

Also tells me he has to run the A/C or the elec cooling fans don't run. (DOH!! Again)

Found a broken fan sensor pin at it's connection to the harness, so obviously the engine overheated at least a few times. Jumping the pins made the fan work, so at the VERY least needs a new sensor.

Checked the top radiator hose temp w/ infrared therm (right next to the radiator) with the fans running: 230deg F, and the bottom radiator hose: 130deg. I seriously doubt the radiator could cool a full flow of coolant by 100 deg, and If the cool 130deg water was actually circulating, the top hose should not be 230deg, so he also may have a partly clogged radiator, or a water pump with a plastic impeller with broken impeller blades. UUGH!

He also said the car has overheated at 50mph on level roads unless the electric fans are running. The radiator looks free of bugs or other blocking debris, so that reinforces that the radiator is partly clogged, the thermostat is partly closed, or the water pump impeller is broken (that said, I've never seen plastic blades on a Honda pump that could break).

The plot thickens.

I think he has likely a bad head gasket, possibly a partly stuck thermostat or a partly clogged radiator,

Opinions before I replace the radiator and thermostat (first), before pulling the head? He needs the car to keep running since he and his wife have 2 jobs but one car, and cannot be "down" long enough to DO a head gasket job right now.

I am hoping that getting the fans, radiator, and thermostat working right will give him time to schedule a head gasket job?

Sound reasonable?

 

On these cars overheating almost alway means head gasket. If it wasn't the head gasket before the first time it overheated, it is now. My car had the exact same symptoms this car has. I swapped the engine with a jdm d17a and overheating and misfire stopped.

 

Perfect!

Nice to know that your head gasket created exactly the same symptoms as in my friend's car!

I've seen many head gasket failures, and most result in coolant loss, over pressure and boiling over, and often sweet smelling glycol odor in the exhaust.

This is a more subtle symptom (at least at first). Most times I suspect it progresses further before being identified.

Thanks all for helping me to ID it early and track down the cause (likely the inop cooling fans) though the fact it overheats now even on a level road at cruise speed points to a restricted thermostat or clogged radiator points to other problems contributing.

Strange the owner didn't see it relevant to mention the overheats and fan situation until I started asking specific and probing questions.

 

Do the tests for a bad head gasket. Very common on these engines for the head gasket to leak and cause cooling issues and misfires.

 

Update-

Last evening I replaced the radiator and thermostat for my friend.
Removing the overflow tank, I found a small hole mid-way in the upper rubber hose that was allowing the overflow to likely go INTO the tank (which was always full my friend informed me), but NOT get sucked back into the radiator on cool-down (since the hole allowed air to go back into the radiator rather than liquid).

This no doubt contributed to the radiator pumping itself out, or at least low over many heat/cool cycles.

Also replaced the fan control sensor near the thermostat housing, and the broken harn)ess plug for it (that some prior "mechanic" had broken and taped over with black electrical tape),. Obviously the same "professional" had removed the engine ground strap to the radiator support and left unconnected (and neatly tucked out of the way)..

In the past, idling the engine even briefly w/o the cooling fans spinning, immediately allowed the temp to head toward red line, but after these replacements, idling the engine for almost 30 minutes saw the temp gauge hover at 40%, and when the vehicle was placed in gear (auto trans) the temp finally hit midpoint (heat load from transmission?) and fans came on for 20 seconds maximum and shut off as the temp gauge returned to the 40% point immediately.

The problem is that I can't be sure there were not air pockets in the engine cooling system before we did the work last night contributing to the problem, but as of last night, things seem MUCH better.

I plan to adjust his valves soon, and then if symptoms persist, indicating ahead gasket problem, it will need to be replaced, obviously.

I figure he can drive the car for a while, keeping his eye on the temp gauge and checking the coolant, and of course, observing to see if the misfire DTC and stumble returns. I await word from the owner on how the car is behaving.

Thanks to all, and I'll update...