Engine RPM fluctuating badly during cold start

[hi577]

Hi everyone...i have a FZ6 S1 Year 2004 since 2011. recently the engine rpm fluctuate badly (between 1200rpm to 800 rpm) during cold start. in the space of 6 months i had clean the throttle body and the k&n air filter. i even replaced the spark plug. what troubling me the engine stall when i am on half clutch to move off. a few occasion i almost fall due to sudden engine stall. to avoid that i will ramp up the rpm before releasing the clutch. however and surprisingly when the engine is hot this does not occurs. it just work perfectly after that, either i am stopping at the lights or junction.it only occurs after the bike is off for half a day.hope someone can shed some light on what should i do.thanks

 

[Motogiro]

There is a sensor that tells the ECM where the temperature of the engine is and ajusts a little more fuel to compensate until the engine temp is warmer. There are many factors that may add to the bike running lean in it's cold temperature range. There is also and air temperature sensor. First you'll want to check that you don't have a vacuum leak. If this is a new problem a new vacuum leak may have occurred. Check the throttle body hoses including the surrounding vacuum lines. I'm sure some of our other helpers will weigh in on this.

 

[Motogiro]

Also: I see a 5th fuel injector in the schematics. This injector would be for enriched fuel mixture when cold and possibly additional fuel at other needed times.

 

[hi577]

There is a sensor that tells the ECM where the temperature of the engine is and ajusts a little more fuel to compensate until the engine temp is warmer. There are many factors that may add to the bike running lean in it's cold temperature range. There is also and air temperature sensor. First you'll want to check that you don't have a vacuum leak. If this is a new problem a new vacuum leak may have occurred. Check the throttle body hoses including the surrounding vacuum lines. I'm sure some of our other helpers will weigh in on this.

I doubt it is due to vacuum leak due to punture/leak hose else the rpm will remain unstable throughout.anyway i'll take your advice to do a check of the hoses....is the air temperature sensor is the one in the airbox?

Oh ya.i forgot to mention...after cleaning the throttle body and filter there was temporary relief.the problem resurface after 2 months.