I have RSX Type S. And I get misfire code P0303 and sometime P0304! I only have CAI. Here is what happen at Honda dealer! When "Honda diagnostic computer" is plug in my car we can see live what happen with the engine while it's running. If misfires happen, we can see it with the misfire calculator. So here is what happen: At idle (775 rpm) Honda computer see misfires and count it like 1... 2... 3... .....10... 11...12... and CEL turn on. But, if I press gas pedal and set rpm at 850, 1000, 2000, 2300, 4000 or 4500rpm, ENGINE HAS NO MISFIRE!!!!! As soon as engine come back to idle (775rpm), misfire come back!!!!

What do you think about that????

 

Small vacuum leak? What is the O2 sensor doing? OBD2 code PO303 and PO304 are misfire detected in cylinder 3 and 4, respectively. Anything those two cylinders share could be suspect.

Although there is no misfire registered on the misfire counter at higher rpm do you feel a misfire? If so the scan tool may just shut off monitoring at higher rpm. Check the basics, in this case spark plugs and coils including the rubber extension that comes off them since this is a coil on plug car.

Have you noticed anything else wierd about the car lately, smoke, burning smells, etc.?

-Scott Tucker

 

You could have bent or improperly adjusted valves (too tight). This causes probelms primarily at low RPM.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dogginator &raquo;</TD></TR><TR><TD CLASS="quote">You could have bent or improperly adjusted valves (too tight). This causes probelms primarily at low RPM.</TD></TR></TABLE>

Aren't they hydraulic?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AutoEng2002Si &raquo;</TD></TR><TR><TD CLASS="quote">

Aren't they hydraulic?</TD></TR></TABLE>

No. They are rollerized, however, the the valves are adjusted with a feeler gauge.

 

I get misfire on cylinder no3 (P0303) since the beginning of cold temperatures (I leave in Quebec). When I start the engine for the first time of the day (generally by a cold morning), CEL turn on. When engine is partially to completly warm, CEL never turn on! Honda told me the code was P0303. After many test, Honda told me that spark plugs, coil pack and injectors seem to be ok.

When I start the engine in the morning, but after about 1 minute, when I listen to the muffler, I can hear the sound of the engine running only with 3 cylinders. CEL beggin to flash. Sometimes it stops flashing, sometimes it stays on after many flash. So here is the sequence: I start engine, everything is ok.... 1 minute later I hear misfire in muffler.... 30 seconds later CEL begin to flash... 2 minutes later CEL stop flashing or stay continuously on... as engine is getting warmer, misfire seems to disapear when I hear the muffler.... when engine is "mid-warm" to warm, I hear no misfires in muffler. Later in the day, If I start engine and it is not completly cold, I hear no misfires and CEL never turn on!!!! If engine is completly cold, the same sequence begin again.

Now, you ask me if I get misfires at higher RPM. It doesn't seems to.... CEL never turn on on the road when engine is hot.

The question is: What happen in a completly cold engine that never happen in a warm or partially warm engine????


Modified by vvtteecc2001 at 9:13 PM 1/4/2006

 

I would try a compression check and then do a valve adjustment.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dogginator &raquo;</TD></TR><TR><TD CLASS="quote">I would try a compression check and then do a valve adjustment.</TD></TR></TABLE>

What is the best: compression test or leak down test?

 

Do the compression first, since it is cheap, easy, and informative.

 

How does the engine runs? Does it run smoothly when you accelerate? Does it feel like it has as much power as it did when it was new or does it feel like there is definately something wrong with it?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AutoEng2002Si &raquo;</TD></TR><TR><TD CLASS="quote">How does the engine runs? Does it run smoothly when you accelerate? Does it feel like it has as much power as it did when it was new or does it feel like there is definately something wrong with it?</TD></TR></TABLE>


Very hard to say!!! It seems to be as smooth as it used to... But a slow deterioration of the engine (valves, sleeves...) is certainly hard to detect!

 

What year is your RSX? Have you checked for service bulletins?

 

Check to see if you've jumped time.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by amckee &raquo;</TD></TR><TR><TD CLASS="quote">Check to see if you've jumped time.</TD></TR></TABLE>
On a timing chain?

Do this.....if it happens when cold then you need to check things that happen when cold. If you have a leaking injector it will bleed off during the night into the combustion chamber and cause a first start misfire(most common problem). Monitor this with a fuel pressure gauge if possible(special fitings from honda needed) Should not bleed off more then 10 psi in 1 half hour. Next you need a diagnostc tool.... monitor the data list when running. You need to monitor the MAP reading whch will tell if tight valves are causing a cold start misfire. Map reading should be steady around .80-90. Anything above that when warm is a sign of tight valves(highly unlikely but worth a shot). Also....have you misshifted recently? You may have bent a valve...slightly. Most noticable when cold when the valves are tight and at low rpms when the motor is easier to mointor and when a misfire is most noticable. My guess is a leaking injector. If it goes away after driving or warmup and only comes back when sitting for extended periods of time....you have found the culprit. Be carefull of extended misfires as they will permanently damage the catalytic. Honda recommends nothing over 30 seconds between periods of misfires.
Good luck.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AutoEng2002Si &raquo;</TD></TR><TR><TD CLASS="quote">What year is your RSX? Have you checked for service bulletins?</TD></TR></TABLE>

2002! No service bulletins concerning misfire!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IMALLSLO &raquo;</TD></TR><TR><TD CLASS="quote">
On a timing chain?

Do this.....if it happens when cold then you need to check things that happen when cold. If you have a leaking injector it will bleed off during the night into the combustion chamber and cause a first start misfire(most common problem). Monitor this with a fuel pressure gauge if possible(special fitings from honda needed) Should not bleed off more then 10 psi in 1 half hour. Next you need a diagnostc tool.... monitor the data list when running. You need to monitor the MAP reading whch will tell if tight valves are causing a cold start misfire. Map reading should be steady around .80-90. Anything above that when warm is a sign of tight valves(highly unlikely but worth a shot). Also....have you misshifted recently? You may have bent a valve...slightly. Most noticable when cold when the valves are tight and at low rpms when the motor is easier to mointor and when a misfire is most noticable. My guess is a leaking injector. If it goes away after driving or warmup and only comes back when sitting for extended periods of time....you have found the culprit. Be carefull of extended misfires as they will permanently damage the catalytic. Honda recommends nothing over 30 seconds between periods of misfires.
Good luck.</TD></TR></TABLE>


Thanx for this informative answer!!!

For the next step, I'm gonna do a leak down test. I'll tell you result as soon as possible!

 

Please do that.