Okay, I started this thread but things kind of changed…

I am still getting P0304, misfire on cylinder 4. I started to pay a little more attention on the idle and when I first start up the car. My CEL usually comes on in the morning and the first few minutes of the drive.

I noticed once I turn on the car, the RPM was at ~1.5k and idled okay. But as it began to warm up and RPM started to drop, I noticed the idle started to get rough, and got worst as it dropped down to normal. If I raise the RPM back up to ~1.5k then the car idles fine again. I also noticed the CEL would go away if I drive the freeway for a long period of time.

Any clues? Could it be some kind of vacuum leak around cylinder 4? Maybe the intake manifold gasket or something, and that’s why once it warms up the car idles fine?

Help!

 

Okay, for the last couple of days and last tank of gas I've been warming up the car before I start driving it. It seems to be a bit better now. Idle is not as rough and I haven't seen the CEL yet. I am also using 91 now instead of 87 (I have 00RS). We'll see how many tank of gas I can go through without the CEL...

Right now I am just focusing on my brake pads/rotors. They are going tomorrow... I hate haing two high mileage cars! Everything happen around the same time.

 

https://www.i-club.com/forums/showth...ighlight=p0304

updated on the wrong/old thread... well... the CEL is still there and the rough idle as well.

 

found this...

https://www.i-club.com/forums/showth...ighlight=p0304

wonder if I should replace my injectors...

 

https://www.i-club.com/forums/showth...ighlight=p0304
fuel injectors

https://www.i-club.com/forums/showth...ighlight=p0304
knock sensor

http://www.rs25.com/forums/showthrea...d=1#post495652
valve adjustment

Also Seafoam and Lucas Fuel Treatment

 

not sure if i want t o spend the money just to 'try' them out...

 

got more instructions on how to remove the injectors. I guess it's not THAT bad.

I am going to pick up a bottle of Sea Foam today from
3780 STEVENS CREEK BLVD, SAN JOSE, CA
Tel: 408-246-8090

I'll run that for my next tank of gas and we'll see if that helps...

If not, I'll be swapping the injectors (2<->4) next to pin down the bad injector.

If the code stays with P0304, I'll try the knock sensor next, then valve adjustment last...

 

I changed the PCV since it's so cheap... But DAMN!! Look at this sucker (old, new, old, new)! the old one is not stuck or anything, but might not 'move' as well due to all the crap on it...






I injected ~4oz of Sea Foam through the PCV while engine on and ~.33oz after I turned the engine off and let it sit for ~5 minutes. I then put the rest of the 11+ oz of Sea Foam into the gas tank with ~6 gallon of 91 octane.

It's driving VERY smooth right now but we'll see how it goes tomorrow morning...

 

update... CEL came back on a little while a go since I started the Lucas fuel treatment. then later went away on its own. I am on my fifth tank with Lucas fuel treatment and my gas mileage has gone from 20, to 22, 23, 24, and now 25. I really hope this is going to fix it since my Smog Check is due next month!

 

sea foam helped my rough idle but lowered my MPG a little bit. what the description of the CEL youre getting?

 

misfire on cylinder 4. always the same... the misfire doesn't move to any other cylinder...

 

I might be heading down the wrong path here, but have you checked the plugs?

 

new OEM plugs, wires, and coil pack is good....
keep asking, you might hit something I haven't thought of...

 

well I'm not very knowledgeable about engine troubleshooting, so spark plugs is where my ideas end pretty much. However, what tests have been done to the engine? If you're in SF, try hitting up Method 4 Motorsports (MethodBuilt is the username here on i-club) and see if they can help you. Maybe a leakdown test if youre thinking it could be a bad gasket

nevermind, I though you were in SF, no SJ. Still try either Method4(South San Francisco), or GST (Hayward)

 

I've contacted GST about this already. The best they can do is to swap the injectors on the same side to see if the code follows the injector. If it does, then I have a bad injector. It's pretty much down to the injector right now... But I am too lazy to swap the injectors.