Hey guys, i have a major problem with my 2002 2.3L F23A1 accord

car has just over 96000 miles on it.. original engine and 5spd trans, well maintained under my care and previous owners claimed to have maintained it well also.

EDIT: engine is all stock. no mods.. in case that matters

recently developed a low RPM miss. at idle to around 2500 it has a distinctive misfire, very noticeable, and the check engine light flashes which is a further indicator of how bad the miss is.

i've narrowed it down to cylinder number 2 for sure.

here's the details..

after a recent trip on the highway averaging about 80mph for 200 miles with one stop in there.. it began to miss at idle.. now the accord has been burning oil for a while.. so i assumed the cylinders were carboned up.. went to a parts store where i was at, bought a can of seafoam deep creep (used before and cleared a high RPM miss i was having right up) and a fresh set of plugs (had my tools with me so i figured why not) after using the deep creep i changed the plugs.. no change.. the miss is still there.

plugs that were in the car were clean in cylinders 1 and 4, and pretty dirty in 2 and 3.. (leaning towards oil consumption through the PCV system like preludes are known for?)

pulled the fresh plugs back out.. cylinders 1,3, and 4 plugs are clean and nice looking, and cylinder number 2 turned black instantly. okay.. major carbon build up.. so i deep creeped that cylinder by itself. put the plug back in, and fired it up.. ran it up to 2500 and held for a good couple minutes.. let it idle.. still missing.. checked that cylinder plug again.. still black and nasty.. although it wiped off for the most part.

so after a long long day of tinkering and basic troubleshooting(i was far from home after all) i ended up discovering the car ran okay at 2500 and up and drove it the 200+ miles home with no flashing check engine light and no detectable misfire except at idle... did notice a loss in passing power though.


minor details, i kept the oil up as it consumed it.. used a quart there and a quart back.. so that's 2 full quarts in 400 miles of highway driving at 80mph/3000rpm about the same as it has been since i bought the car... so nothing new to me...


after getting back home, i pulled the plugs after the 200 mile trip.. cylinders 1,3, and 4 are still nice and clean.. cylinder 2, filthy and black.

so i swapped injectors from cylinder 1 and 2, misfire did not move to cyl 1.. okay so it's not injector related.. swapped plug wires at plugs and dist. still no change.. so it's not ignition related.. definitely number 2 only.. pulling plug wires off any cylinder except 2 at idle yields and instant response.. pull #2 at idle.. no change.. so it's definitely #2


as i said before, after 2500-3000rpms.. it smooths right out and is un-noticeable, except for a drop in passing power.. which is partially due to the disgusting fouled plug in that cylinder. no drop in coolant levels.. nothing indicating a head gasket.


so basically.. i'm at the point where i'm gonna do a compression/vacuum test and most likely end up having to pull the head i think. losing a single cylinder is a rather odd situation.. it points at an isolated issue in just that cylinder, meaning, bad/burned/sticking valves or bad rings/cylinder wall.. or another option (related to oil use) is completely gone valve stem seals allowing unmetered air/oil to get sucked into the cylinder causing a fuel mixture problem and excessive carbon.

also, i pulled the valve cover and visually inspected the mechanical assembly and there does not appear to be ANY loosening or wear of the valve adjustments which i performed less than 2k miles ago.. so that's out as well.

cap and rotor were replaced less than 5k miles ago, checked and are still in good condition

so basically.. i need help.. any more theories, ideas, tests i should do, maybe someone else has experience this ??

i really need some help on this one, i don't wanna go pulling the head for nothing. as i said, 96k original miles, first time i've ever had symptoms like this on this car.. owned it since 87k miles and aside from higher rpm misses developing from carbon due to oil consumption over time which were solved by de-carboning the cylinders the car has run fantastic and always had great power.


thanks,

Moddage

 

What kind of spark plugs? Hondas seem to like NGK best.

 

NGK platinum plugs what i've always run since i got the car.. plug type and brand is irrelevant to the problem i'm having right now anyway

 

Some people have said they get misfires with Bosch plugs in Honda engines. That's why I asked.

I hope someone else chimes in, but if it was me, I'd plan on pulling the head to look for valve problems. Lots of work, so hopefully someone else has an idea.

 

cylinder head will most likely begin to be torn off tomorrow.

did a compression test.. while cranking the engine over with plugs out.

cylinders 1,3, and 4 peak at 180PSI during cranking

and cylinder 2 rings in at 50PSI

with the compression tester hooked up and rolling the motor by hand, cyls 3 and 4 peak at 30PSI cyl 1 peaks at 27ish and 2 registers 0


fired the car up with cylinder 2 plug out (useless when it's in anyway) and had the compression tester hooked up. peaked at a max of 60PSI at engine idle.. and when revving up to around 3000RPM peaks at 120PSI (hence why it smooths out and runs semi-okay above 3000rpm) still low..


hooked up a vacuum gauge inline with the PCV valve and at idle it fluctuates between -17 and -20 inches of mercury rapidly. i'm leaning towards burned valves in cylinder 2. i can't imagine rings went bad in one cylinder with 96000 original miles. maybe a head gasket ? regardless, the head has to come off for any of the above potential problems.

now the question is.. do i re-build my head.. or buy a reman. head ?


time to start pricing stuff out...

 

Testing compression by hand-cranking doesn't mean much. Also when the engine is running at higher RPM can't be compared either.

So... warmed-up engine, all plugs removed, fuel disabled, throttle WIDE OPEN, crank with starter. That way cyl#2 is way lower than the others.

Repeat the compression test after pouring a tablespoon of engine oil into the cylinder. If #2 comes up sorta close to the others, then you can blame the rings. If it still measures low, then blame the valves.

Valve lash adjustment? It's a long shot, but check the valve lash especially on #2. If it's way off, make it right & try running the engine again. Then repeat the compression test. Like I said it's a long shot, but it's a lot easier than pulling the head.

 

okay.. i did the crank test with the engine warmed up before i posted..

the results as i got were 180 in 1, 3 and 4 and 50ish in 2


after adding a little over a teaspoon of motor oil to the cylinder.. the result was 60 PSI


so it didn't do much of anything...


valve lash is where i started the other day... cylinder number 2 valves in the closed position the valve rockers were all loose and had play.. about the same play as cylinder number 1.. i didnt have feeler gauges to check exactly where it was but it was in the same physical travel range as cyl 1 so it can't be too far off...

i just adjusted all 16 valve lash adjusters less than 3k miles ago... and they don't progressively get tighter over time.. they loosen or wear away... meaning the valves would not stick open from a worn lash adjuster... rather closed too long.

which means if the lash was off.. or too sloppy.. i would have fantastic compression still in that cylinder. so that rules that out... but good thought


EDIT: the head will be off the car within the next 4 hours..

i'll let ya know my findings..

also.. i posted on honda-tech and got a reply about a cracked piston ring land... or rings...


what are the odds of rings or a ring land going bad all of the sudden like this after only 96000 miles ?

i'm still leaning towards valves... i'll have a better idea in a few hours here..

 

Gotta get in there & look. If you REALLY have to know before taking off the head, you need to go into the sparkplug hole with a borescope or something like that.

Hole in the piston would give about ZERO compression, not 50.
Bad rings would improve more when you put oil in there.
Valves burned? Bent?

Whatever it is, at this point you gotta remove the head & look.

 

cylinder head is off the car as well as the entire timing assembly..


cylinder number 2 exhaust valve closest the the passenger side of the car has a nice chip out of it. there is no evidence that the valve and piston ever met, so apparently something must have gotten into the cylinder at some point ?

that would explain the no compression... hahaha

cylinder walls on 2 and 3 look pretty awesome from what i can see.. i didn't check 1 and 4 yet as they were at TDC and i didn't feel like working on it any more today..


so now i'm at the point where i begin the process of calling local engine shops and finding out how much a complete head rebuild is. and then deciding if i should do that or buy a rebuilt head.

i also damaged some kind of sensor in the process right under the intake manifold.. no idea what it is.. but most likely going to the local honda dealer for it..

but anyway, the verdict is in, cylinder number 2 has a damaged valve. 1,3 and 4 all look pretty good.. the exhaust valves are pure white in those 3 cylinders and the rest of the combustion chamber and intake valves are black... cylinder 2 one exhaust valve(the one that IS NOT damaged) is black, and the one that is damaged is white-ish and starting to turn black.

 

#14 is the knock sensor
#15 is the oil pressure switch


Sometimes it starts out as a tiny chip in the valve, then it grows by erosion because the combustion gas is so hot. Make sure you (or the shop) checks the valve seat for similar damage.