I have a 2008 CRV with 120K on it. I am having misfire issues on startup. Code: P0303 or P0304 (either a misfire on cylinder #3 or #4, never both at the same time). Misfire occurs for maybe 5 seconds then goes away and the car runs fine. Does not happen every time and seems to be random.

So far, I've replaced the spark plugs, all coil packs, and all injectors but the problem continues.

Does anyone have any ideas of what is going on and how I can fix this?

 

welcome to the forum. when the engine is cold, take a compression check of all cylinders,

 

Assuming it is a small vacuum leak such as a intake gasket, it would misfire at cold start up.
Then when warmed up, the engine expands and fills up the space and vacuum leak is gone.
It may not happen every time.
If it only happens for a few seconds then very hard to check or diagnosis

If ACmech is correct then it could be mechanical.
Sticky valves. It might show up in a cold compression test.
Must carefully watch the dial.

 

I have the same issue, also 2008 CR-V, but higher mileage. On cold startup it holds 1500rpm and steadily decreases, but blips every few seconds, slight imbalance in the engine, feels like a misfire. No codes at all, and goes away completely after it warms up and idle settles at 700rpm, also drives fine.

So far did a quick Maf sensor clean with alcohol, but I'm wondering if it's PCV related or if OP found a fix..

 

How do you know they don't misfire at the same time? Do you have a scan tool? Not a reader.

 

You dredged up a 4 year old thread. You might try sending the Author of the OP a PM to see if there is anyone home.