this a 4g63 problem I'm having, but it fits in performance/engine (who checks the 4g63 section anyway)

Engine throws a code P0304 -cylinder 4 misfire. Idles horrible, but engine smooths out in higher rpms.

And a new plug looks like this after 50 miles (see the plug 4 on the very right of picture)


New wires, new plugs, same problem. Dino said by the look of the plug, it was stuck open / leaking / failed injector. Replaced the injector. no change.

Checked ignition coils. Secondary is within range. Primary is slightly out:(ref range is 0.7-0.86 kOhm)
- 2&3 terminals 1.2 Ohms
- 1&3 terminals 1.2 Ohms

Don't know if that's enough difference to cause the ignition coil to fail. And don't see how that could cause just cylinder 4 to misfire. I would think both cylinder 4 and cylinder 1 would misfire.

Are there any sensors that will cause just a single cylinder to misfire?

Could be a valve if it wasn't the injector. Do a compression test.

oh crap. now that you say that, I wonder if there is a connection with the crappy timing belt change that was performed earlier...

I got a compression tester from autozone, will do that next.

Here's something else I just noticed. When you first turn on the engine, it idles FINE for 5-15 seconds. Then it starts to idle like crap. If you turn off the car, and then turn it on again a short time later, it will idle bad from the start. so it only happens if the engine is a little warm. hmmm...

Another guy at tooners had a 3rd cylinder misfire and the same situation as me - turned out to actually be an O2 sensor! I hate 4g63s


EDIT: compression is fine. It looks like a rat has been eating some rubber hoses. I haven't found any punctured hoses yet, but if this is all due to a vacuum leak... it's time to get another cat.

And get normal copper plugs. You have some janky iridium and dual electrode crap there. NORMAL STOCK NGK. Just because the sooper +2 platinidiumextract quad core dual xeon sparkplugs cost $8 each instead of $2, doesn't mean theyre better.

yea I told him to just get copper plugs. he didn't listen to me.

Another posibility is the actual injector circuit on the ECU.

Exile Racing Technologies
http://www.exileracing.com
Go that way, really fast, if something gets in your way... turn.

Originally posted by Michael_97RS
Another posibility is the actual injector circuit on the ECU.

HE LIVES!