How to troubleshoot misfires

Tips on how to troubleshoot common BMW issues.
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bimmertips
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How to troubleshoot misfires

Post by bimmertips » Fri Apr 20, 2018 3:19 pm

Misfire codes are common. There can be many causes anything directly related to the fuel and ignition systems. Below are some basic tips on items to check for troubleshooting misfires.

This below list are the most common issues, although your misfire may be from other sources.

Spark plugs
Spark plugs are bad causing a misfire in the cylinder. Replace bad plugs

Coil packs
Bad coil packs cause the spark plugs not to ignite. Check the manufactured date on them to see how old they are. If they are original or have over 100,000 miles on them they are likely bad. Swap out the misfire cylinder coil pack with a known working cylinder coil pack. If the error code follows the cylinder it is a pad coil. Remove and replace.

Fuel injectors
Dirty or faulty fuel injectors may not be injecting enough fuel into the cylinder for proper ignition. Try fuel injector cleaner, rebuilding the injector or testing fuel flow to see if they meet OEM specs.

Fuel pump
A bad fuel pump may not be sending enough fuel to the injectors. You can rent fuel pressure gauge from a local auto parts store. Test the fuel pressure off of the pump and see if the flows are within factory specifications.

Fuel
You may just have bad fuel. Water in fuel can be very harmful to your engine. Are you using too low of octane and getting pre detonation? Make sure you are using the minimum octane rating that is designed for your engine. BMWs have compression motors and require high octane fuel to prevent predestination of fuel.

Fuel filter
A clogged fuel filter may be preventing the proper flow rate of fuel getting to the injectors. Make sure you stay on top of maintenance and replace your fuel filter every 10k-15k miles. It will pay for itself over time as a clean fuel filter will get you better fuel efficiency.



Michaelnic
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How to troubleshoot misfires

Post by Michaelnic » Sat Jul 28, 2018 12:30 am

I waste wayyyyyyy too much time on here and other forums of the internet, its hurting my productivity.

How do I delete?

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