Causes cylinder misfire

SOURCE: misfire on cylinder 4 & 5. combustion miss with cylinder cutout.

the best way to diagnose a misfire is to move the ignition coils of those cylinders(4 and 5) to different cylinders to see if the misfire will move. you can also move the injectors around and even the spark plugs.(make sure to keep a good record of where you are moving them). if you can't get the misfires to change cylinders. your next step would be to do a compression check on all cylinders. air leaks in the intake system can cause misfires but usually it isn't on the same cylinders all the time

Jun Magno

• 175 Answers
• Posted on May 28, 2009

SOURCE: BMW 523i 1999 model

your car is not suppose to idle at 500 rpm . 800 to 950 is the proper idle, unfortunately it is controlled by the computer. have you checked the idle speed control valve? also check the air flow meter

SOURCE: 2001 bmw 325i is misfiring?

misfire happens because there is still fuel not burned in the cylinder so when its pushed out its burned in exhaust tube because the heat thats why you hear these small explosions. this caused if your sparking pluge not firing well . or there is a leak in the intake valve . in your case i advice you to check your sparking plug . if this helped pls vooote

SOURCE: Check Engine Light coming on

get the soft ware up grade. and have the coils checked.

William Robinson

• 144 Answers
• Posted on Aug 30, 2010

SOURCE: I have a BMW 3

P0300 indicated a multiple cylinder misfire. Typical causes are vacuum leaks, bad plugs, wires and/or coils. Could also be a dirty MAF. From what you describe it could also be the seal between the air cleaner housing and the MAF. Make sure the o-ring is not out of place and dry. I put some silicone lube or vasaline on it to help seal things up. That fact that it acts this way when cold points in the direction. That's what I would check first. Let me know how it works out.