Ok as stated above, 2003 EP3. It's my brothers car and I am stumped. Let me start from the beginning. CEL for catalyst efficiency (which is exhaust leak, cat failure, or secondary 02 sensor failure). SO we pulled both the upstream and downstream 02 sensor and both passed with flying colors. And there is no exhaust leak. So we turned the car on and raised the lift up so we could test the cat (delta of 100 degrees before the cat to after it.) When we lifted it up the exhaust started to have this small shaking, which looked like a misfire, but there was no temporary or permanent code for a misfire. So scratched that cat testing idea and lowered it down and looked under the hood. You could feel a misfire, but it was not a true misfire like an actual dead cylinder. Well we ran a data stream on the RPM and unplugged one coil at a time to see which cylinder made the least drop.......AKA cylinder power balance test. SO cylinder 2 came back with a very minor RPM drop. So we swapped coil packs from 3. No difference. Swapped plugs from 3. No difference. Pulled the fuel rail and changed all the injector o-rings. No difference. Pulled the rail again and swapped injectors. No difference. And then today I did a compression test (wet and dry) and it passed that. Any ideas? Only thing I can think of just doing a cylinder leakdown test. Just dont have a tester unfortunately. Any help would be appreciated.

 

you stated everything i would think of to do, i would say try leakdown test, if it doesnt work, try the stealership or a mechanic/tuner you trust

 

So what's the root of the problem? Just the CEL? Or is it running like crap - you described it as misfiring.

When was the last time you changed spark plugs? Checked your ground connections? Checked the timing?

Keep in mind...a faulty o2 sensor CEL code isn't always caused by the cat/sensor itself. There are many many other contributing factors.

 

<-- Pearl drummer

also how many miles are on the engine?

 

haha TAMA FTW!!!

anyhow. to the first guy, i do work on cars, hence why i have just about all the tools i need. I am actually about to get a job at honda. but yeah leakdown is the next thing. To the pearl drummin turboeg guy, the root was originally the CEL. And it is running rich and having worse mileage than before. Which is why we went to the 02 sensors, and why we tested the both of them even though the code specified the secondary one, the first sensor is for the air/fuel mixture and all. The car runs good, and thats why this "wannabe misfire" was never noticed. Every other cylinder runs good, and number 2 just seems to run crappy.

 

oh the mileage i think is like 100,000 some. nothing crazy.

 

I'm still voting for a spark plug/timing issue. Check your plugs

Without knowing more maintenance history of the car, I'd recommend starting with plugs first because it's the easiest thing to check.

Good luck mang.

 

plugs are good. not old at all. and cylinder still ran crap with number 3's coil and plug combo. and cylinder 1,3, and 4 ran great!

timing is next i suppose.

 

bump. anymore ideas??

 

Header to cat "O" gasket may be toast...when they start to go, they go when the motor is under load( motor is rocked in its mounts)...people mistake the extra noise for the raw power of the a3 motor...........
When you clear the cel by pulling the ecu fuse, how long before the cel pops again?....how much run time , miles?

 

when the codes are cleared, it is a normal two key/drive cycle until it comes back.

but that would be an exhaust leak, yes, but that would not make cylinder two basically run 50%.

 

not sure if this would help, but I had my cell on after installing straight race header w/o any cat on my 01 lexus is300 and that tripped the Trac control to go beeswax..., so I got a o2 sim and the problem went away and pass the emissions as well. if the problem goes away when codes are cleared, why not find a way to delete the code? now, if there's more serious underlying problem this prob. not be a help, but I just thought I pitch in my 2 cents.
FYI, i got my o2 sim from o2simulator.com or something like that for $6 ish...

 

well, it is a completely stock ep3. so no race header, though my brother does want one.

we just want to try everything we can besides the worst case scenario, which would be taking the head off. but we will see.

 

ok bumping this thread up. still havent fixed it,

i had a thought though, what if one of the lobes on the cam was messed up, like one of the non-vtec lobes for cylinder 2? or what if a valve spring or something was not right, causing good compression, but bad power, like the valve is not opening all the way?

 

Ding ding ding. You may have hit the jackpot.

The 02-03 motors have known problems with cams. They tend to get galled/pitted out with high miles due to poor quality castings. The issue hasn't been a problem for 04-05 motors.

Pull the valve cover and visually inspect the cams. You might be surprised what you find

 

ok, see now we are making progress hahah. yeah i dont know much about the ep, i am an accord guy. so thanks a lot man, and i will have to check it out.

now, if i get a new one or used one, should it be from the 04-05? or if it is new did they fix the casting problems to be able to get the 02-03 one.

 

Could be the cams...the 02-03 cams may have has had a heat treating issue...I still think its that 5w20 oil they sugest for the motor but thats just me....the 04-03 motors have the same cams as the cr-v k24a1 motor....If you want to up grade, the junk2 stage ones will run fine with the stock ecu.

 

I've actually heard that it was recommended for the 02-03 model EP's to change your oil with 5w-30 and not the 5w-20 that is recommended on the oil cap for that reason.

Mustclime, is that really true about the stage 1's? Will there even be a gain with out tuning?

 

yeah, i want to know the same thing about the s2 stage 1's. because if we have to replace the cams, might as well upgrade them.

can they run on a 100 percent stock engine on no tune and make any difference?

 

the great rule of cams.....if you do not raze the redline....never expect more than 8-10% of a hp change....back in the day, some kid in philly did a hp test on stage-1,2,3....I think stage one was good for 8 whp, stage 2 was good for 11 whp and stage 3 was something like 14-16whp....stage 3 killed his timing chain.........

 

thats what i figured. i may take the valve cover off this afternoon if my brother gets home from work at a decent hour and take a look.

so what do you all recommend if it is the cams? we are going to replace both of them.
and i just looked on majestic and two new ones are about 600 total. any other options? someone mentioned crv. which years? and any differences in the cam at all? just trying to get him a solution. thanks again guys.

 

$600 for OEM cams brand new? Might as well go with the S2's lol.

 

thats what i figured.

dont they recommend a valve train upgrade though?

i am assuming valve springs.

 

stage ones are fine.....the lift's not that much.........don't forget to put some hondabond on all the corners when you reinstall the valve cover.................if the cams look ok, you might want to check your valve lash while you are under there.

 

hondabond..? why this; just as a precaution?

valve lash.. is this what you mean by using the angled feeler gauges to check clearance and what not..?

thanks