SR20 Misfiring and Rough Idle

[Brandon]

I was driving home about two weeks ago and stopped to get gas, when I turned my car back on it idled rough and misfired when I was driving (I assumed that's what it's doing when it sounds like a lawnmower when you're driving). I checked it out afterwards and thought it to be the gasket for the turbo inlet, so I replaced it, turned my car back on and the problem still persists. It will sometimes, and I mean when I'm slightly on the gas, drive normal and not sound like a lawnmower, but the second I give it more gas or let off it goes right back to having the problem, there's no power but it still boosts fine.

I've checked all my connectors and vacuum lines and have been pulling my hair out over this. I think it may be the o2 sensor, but I'm not too good at diagnosing problems so I recorded a video of it so hopefully someone could help me figure it out.

http://www.youtube.com/watch?v=mg8vbKQgSFg

[SoguRacing]

check the timing, and the spark plugs, could be your problem right there

[fran13]

dude it sounds like a problem i experienced as well and it came out to be an injector and a coilpack....but idk it could be another problem.

[njd07]

defiently a misfire...now you need to figure out wtf is causing it. start off doing this:

try and fiture out which cylinder is down

unplug each coil one at a time(meaning plug it back in after u test it)....if the idle gets even worse that means that cylinder is running ok...but if the idle stays the same thats the dead cylinder.

happened to me several times...1 fix was a bad connection at ecu. I just simply removed ecu and reintslled and it was fixed.

othertime, was a bad maf ground

could be injector, coilpack, etc.

[Brandon]

Alright, I'll check the spark plugs tomorrow morning. I think I remember the problem not changing when I took off spark plug number 3 if you're looking from the front. How would I test a coil pack? Just use a voltmeter?

[slider2828]

Yup and put it on ohm readings. It should be around 11-11.5. I think

[Brandon]

Ok, I just pulled off the connectors to the coil packs one by one and it made the car take a big longer to start no matter which one was pulled off. Still sounded the same when I revved it and at idle. Should I try checking the injectors now?

[Brandon]

Ok so I just went through and pulled the coils one by one again, and then did the injectors. The problem got worse for each one I took off, misfiring worse than it does right now. When I was done with that, it still is having the misfiring problem. It's not a constant thing, it'll idle fine but pop alot. It's more noticeable when I drive, it'll sound like a lawnmower, randomly smoothing out for a second or two, then going right back to sounding like a lawnmower.

It gets worse when I floor it, although if I leave the car to coast in gear, it doesn't seem to misfire at all.

[slider2828]

Did you even check timing?

[Brandon]

I haven't yet, that's on my list to check today. I have to go pickup a timing light first.

[Brandon]

Ok, checked everything, replaced the o2 sensor. Everything was fine, it's still doing the same thing. o2 is reading weird and it's even worse now.

[xtopgun32x]

EVeR figure it out?

[napz510]

Everything happened after you fill up your tank...check your fuel pressure..