2001 bmw 325i is misfiring?

I am guessing the check engine light is on. Scan it with a code reader ($20). You didn't mention what year your car is but most bmws have a 100,000 mile spark plug life span. If you have a misfire code then swap the ignition coil to a different location. Misfire is on cylinder 1 swap the coil to cylinder 4. If you now have a misfire code on cylinder 4 then replace the faulty coil. If you have lean mixture codes check for large cracks in your intake air boots. The oil separator hose also causes a large vacuum leak along with the more expensive vacuum regulator.

You didn't specify year and model. However, assuming it has coil packs, then it may be faulty. Switch the #3 and #4 coil packs and see if the misfire follows to # 4. If so then replace it.

Failed ignition coils

The ones you replaced may not be the issue

Any coil can fail when it wants to

Have to look at cylinder misfire counts on scan tool,
use a scope,walk new coils,whatever it takes to find the
bad ones

wiring faults to coil/s --coil/s --HT leads ---Spark plugs --low fuel pressure --injector wiring--injectors -- faulty injector tips are some of the causes for misfiring. Run the fault codes to check where the fault may lie.

It's either spark plugs/wires, coil pack, bad gas (need high octane) or a timing issue. Check each starting with plugs/wires, then coil pack then check timing (especially if you've had it "tuned")

plugs and wires. yes wires are the biggest issue with a misfiring engine. check the gap on the plugs. sometimes they are gapped to far and cause a cold misfire issue. simply pulling plugs and look at color of the insulator will tell the condition of the engine. normal should be a golden tan color darker means its to rich or burns oil white ask means to hot and should use a colder plug

p0301 is a misfire problem, stands for misfire cylinder 1.
it may caused by Faulty spark plug 1; Faulty ignition coil 1; Ignition coil 1 harness is open or shorted; Ignition coil 1 poor electrical connection; Clogged or faulty fuel injector 1; Injector 1 harness is open or shorted; Injector 1 poor electrical connection; Improper spark plug 1; Insufficient cylinder 1 compression; Incorrect fuel pressure; Intake air leak

greetings

Hello! take the vehicle to any auto parts store and have them scan the On Board Diagnostics (OBDI) To determine the trouble code...With that code they will tell you the component or components causing the misfire...


Guru.............saailer


I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

it doesant sound like its a problem from your spark plugs sounds more like a stepper motor problem make sure you have fitted everthing correctly after you have changed spark plugs sensors ect if you needed to remove elctrical sensors

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