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-   -   Misfire code p0304 (https://www.chevyhhr.net/forums/problems-service-repairs-42/misfire-code-p0304-49126/)

Lucky Jan 9, 2014 09:57 PM

1 Attachment(s)
I like using the vacuum hose at the brake booster. The hose end by #2 on the figure below

donbrew Jan 13, 2014 08:37 AM

I pop the PCV hose off of the valve cover.

Interesting that that TSB is NOT for the 2.2L, but every other one.

hurst2001 Jan 13, 2014 11:50 AM

thanks don brew is this the hose that connects to the throttle body and valve cover ? any pics? I want to clean the intake and valves,and also the crank case with sea-foam thanks...

donbrew Jan 13, 2014 01:42 PM


Originally Posted by hurst2001 (Post 732351)
thanks don brew is this the hose that connects to the throttle body and valve cover ? any pics? I want to clean the intake and valves,and also the crank case with sea-foam thanks...


Yes, from the valve cover to the air horn. That bit of plastic is just an elbow, not a valve. I figured it cleaned the TB on the way in. I could not think of any reason to worry about which side of the butterfly it got in on.

Be sure to securely re attach the hose to the valve cover. A loose one can cause OBDII codes for "too lean" etc.

hurst2001 Jan 14, 2014 12:45 PM

Ok last question when i pull the hose off then start the car and pour it in slowly? just like when you use brake booster hose correct....

donbrew Jan 14, 2014 04:11 PM


Originally Posted by hurst2001 (Post 732458)
Ok last question when i pull the hose off then start the car and pour it in slowly? just like when you use brake booster hose correct....

YES, while your lovely assistant keeps a foot on the gas pedal, revved up to around 2K, IIRC. Look at the seafoam.com site for exact directions.

You need the lovely assistant because the drive by wire won't let you hold the butterfly open by hand.

hurst2001 Jan 14, 2014 07:07 PM

Thanks don brew will do

hurst2001 Jan 20, 2014 01:10 PM

Ok update i have not did the sea-foam yet but i had my battery replaced Friday, it was 6 half years old well since three days have pass no check engine light yea ! So after when i load test it when it was warmer it was marginal ,so my theory is when it got colder and after the car sat all night ,when trying to start maybe it was just getting by but not enough juice and turn on the check engine light for some reason if it possible the motor is idling a little smoother too just kind of weird i say... But problem fixed just passing this on:twothumbs:

hurst2001 Jan 20, 2014 09:36 PM


Originally Posted by hurst2001 (Post 733058)
Ok update i have not did the sea-foam yet but i had my battery replaced Friday, it was 6 half years old well since three days have pass no check engine light yea ! So after when i load test it when it was warmer it was marginal ,so my theory is when it got colder and after the car sat all night ,when trying to start maybe it was just getting by but not enough juice and turn on the check engine light for some reason if it possible the motor is idling a little smoother too just kind of weird i say... But problem fixed just passing this on:twothumbs:

Well guess what its back started it last night with remote start and ran until i open the rear door and shut off and it did it once before ...p0304 this is crazy so next going to run sea foam thur it and see if that works,just thinking if i have a intake gasket leak ?i have check the plug on cylinder no indication of dex cool on the plugs ...just weird only does it when cold ,these is just driving me crazy.. :loco:

donbrew Jan 21, 2014 09:03 AM

I don't remember if you already switched injectors around.

That would be intake gasketS, there are 4 of then they are rubber O-rings. Maybe check the bolts. But, I think you are heading towards internal problems like rings or valves.


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