Got engine check light :(

[jmew0ng]

P0304 is the code that says misfire...
So I'm going to try and swap out the spark plug, but which one is cylinder 4?
on the very left?

[Tamago]

how many miles, and what mods? if you need a new coilpack i have them

[jmew0ng]

40k AEM Intake..
I don't need to change all 4 do I? D:

[Tamago]

clear the code, see if it comes back. do that before you spend any $$

[Loren]

Mine was tripping misfire codes at high RPM last time I was at Sebring. Replaced all four plugs with good ol' NGK V-Power plugs and never looked back.

[YarisSedan]

List what mods you have. If you have a missfire and your car is running okay at the moment is intermitent and could be a high rpm miss like loren says. You only need to worry if the car starts running rough and you have a blinking check engine light. Meaning its missfiring bad enough to damage the cat and possibly 02 sensors.

I would try clearning the code first. And see what happens. The number 1 cylinder is closest to the cam and crank i belive and 4 is furthest away. either way just swap the far left and far right. Then clear code. If it says cylinder 1 is missfiring now then you know you have a coil problem.

If it still says cylinder 4 missfire then you ahve either a spark plug problem, fuel problem, or mechanical problem such as low compression.

If you hav ebeen consistantly running a low quality IE non toptier gas. (toptiergas.com) I would suggest running fuel system cleaner and removing plugs and spraying them down with carb cleaner to remove all the carbon buildup.

[jmew0ng]

ah i'll go give that a shot....
do I just reset ECU to clear code?
and if so, which fuse do I pull again :<

[Spades]

what do the plugs look like? if you swap the plugs and the misfire shows up on #4, if you have a digial camera, take a pic. I am curious to see what the gap is like and the condition of your spark plugs.

P.S. on most cars, pulling the nagative battery terminal off for a few minutes or more will reset the computer...no point in resetting it tho for the first test...if the spark plugs to blame you will get a #4 misfire when you swap the plugs around...and you will just have to reset the computer again.

[jmew0ng]

it's been a few days and light hasn't came back on...
does it mean it just slipped up once or something?

[severous01]

pulling the bat is a bad idea for resetting ecu. the thing has to re-learn your driving habits and fuel economy programming n stuff...you can get a cheap handheld scanner for less than 20 bux now at autozone that will give only code numbers and ability to erase codes......

or, if you're seriously a cheapass you can go to autozone and talk them into deleting codes...they're not suposed to but they will with a little convincing

[msfire671]

ok guys..my light has came on...

i currently have a weapon r dragon sri and recently installed an lpx performance muffler.

ive had the intake for a while now...no problems.
i've had the muffler installed 2 weeks now...any idea why it went on?

i m at 16k is it that time to bring her in for service? i would just hate to bring her in if its something that could be done by deleting the code....

[Yaris Hilton]

Read the post directly above yours. If you can afford a performance muffler, you can afford a code reader. You need to know what the code is when the CEL comes on. And the code reader will clear codes.

[msfire671]

thanks mr. pimpin yaris =] my brother has one and he'll check it tomorrow...crossing fingers that it's nothing serious... =/

[YarisSedan]

really just take it to the dealer this is a warrenty item

[msfire671]

well see i would take it to the dealer...but theres only one toyota dealer here on guam and if i do turn it in to them they might need it the whole day...and this is my only daily driver...but if the code comes out to be a bad thing..then yes i without choice i will take it to the dealer... =[

thanks for the replies! =]

[Yaris Hilton]

Having a brother with a code reader's a good thing.