macson

Hey guys, kinda need some help with this:

98 Civic EX, stock d16y8 other than 4-2-1 header. 160k miles. M/T.

This morning, tried to leave for work, car was misfiring horribly. Seriously felt like it was running on two cylinders, almost couldn't get up a small hill in my neighborhood. Turned back home to take a look at everything.

Had CEL's for random misfire on all cylinders.

Each cylinder has spark. Plugs looked fine, replaced them anyhow.
Wires are fine, no tears or large resistance.
Cap and rotor are fairly new, clean, no water or anything.
Tested the coil and ICM, both are good to go.
All injectors are firing.

I filled up the tank and added a bit of injector cleaner just in case, I can probably rule out bad gas.

When I'm decelerating in gear everything sounds fine, compression is probably alright. Last time I checked it a few months back it was about 185 across.

It has been getting a little better throughout the day, if I keep it around 2-3k rpm with a low load and throttle position it won't misfire, anything else though it will. Sometimes it seems like it's fine, other times it's real rough. Could be timing but since it seems to be alright here and there and getting better, maybe something with fuel? I haven't been able to check the fuel pressure yet, no gauge.

Former User

Try replacing the fuel filter.

macson

That was my next thought too. I'll give it a go tonight or tomorrow morning and let ya know. Anything else I might be able to look at as well?

macson

UPDATE:

Replaced the fuel filter, it has gotten worse now, constant misfire. Could be timing, definitely going to check that tomorrow. Anyone else have any other ideas or anything else to check? I'm going to double check the ICM as well, just to make sure I didn't overlook something. Another thing to note, my car has always had a slight gas/fume smell because of an exhaust leak I have, but since it's started doing this it has gotten pretty bad. Maybe my ignition is messed up and fuel isn't burning fully?

Anyway, any help at all is awesome. I really need my car for work everyday =(

macson

TTT for the night, thanks all

eaglewesman

It seems every time I hear about some problem happening, and standard maintenance is done, it turns out to be a sensor. Anybody know of a sensor that could cause misfires? MAP, TPS, O2, etc? Just a suggestion

ReDJdMBuB

i think the timing might be off......

Former User

I agree. Check whether the timing belt skipped a tooth.

fin781

check the tps and o2 sensor.
there decently cheap, and could probably use replacement anyways.
your o2 can cause it to run rich, but its hard to tell.
if its not throwing a cel for either sensors just random cylinder misfires, then you can
probably for the most part rule these out. also go buy a new set of plugs for like 12 bucks.
replace the simple and cheap things that could cause the problem. it can never hurt if
they need it and then rule out the more expesnsive parts linked to the misfires.

macson

Got it worked out, bumping in case anyone was wondering what was going on or if someone searches this problem...

...turns out I'm just a little oblivious and an idiot lol. My plug wires weren't sealing well on the valve cover, and moisture over time caused the spark plug end of each wire to rust/corrode a bit, I just had extremely poor spark, even though it checked out on a meter and visually they looked okay on the outside metal section. Replaced with NGK wires and it's running great.