Engine misfire cylinder #6

[Charlieb9578]

The car starts revs up fine. Once get on the road and up to like 3rpm 3rd gear the car starts to misfire in cylinder 6. I have replaced ALL sparks plugs and coil packs with oe (not oem) parts. The exhaust camshaft sensor was replaced with oe parts too. Now could it be the intake camshaft sensor? Like I said the cars starts fine then gets up to speed and all the sudden the car misfires cylinder 6. And it get fuel cause I revved it up in the driveway up to 5 rpm plus it drives up until you get to around 3 rpm on the road or but so fast. Camshaft sensor? Crankshaft sensor? What could I try to fix this???

[Muzz258]

Have you read the trouble codes? There may be a clue in among them.

[Charlieb9578]

The trouble code says misfire cylinder #6?

[MarcoZandrini]

There are numerous causes of misfires:
- bad spark plug
- bad injector
- bad injector connector
- bad coil
- bad coil to spark plug connector
- bad coil connector
- bad engine harness
- mechanical issues with the cylinder
- improper fuel pressure
~ fuel pump
~ fuel filter with fuel pressure regulator
- engine computer (DME) problem*

Injectors and coils both get constant 12VDC when the ignition switch is in the run or start position. The DME provides the ground to “fire” them.

[nonturbodan]

If plugs and coils didn't have any effect you need to move the injectors around and see if the problem follows.

[Charlieb9578]

i took it to the shop and they found vacuume leaks and fixed them. Drove the car again after getting up to speed the engine cylinder 6 started misfiring again. However u can turn the ignition off and back on and it will reset the check engine light and engine won’t misfire even if u rev it up parked. It’s once u get going again. If the fuel injectors were bad wouldn’t it show as I rev the car up parked???

[Honolulu]

It sounds like the engine isn't getting enough fuel to run at high rpm under load. It could run just fine in neutral with a bad filter or weak pump. Suggest (again) that you verify the filter is not clogged, and after that, the fuel pressure is good.

[MarcoZandrini]

There’s a fuel pressure test port in the fuel rail. Item #2 in the link is the port’s cap. Fuel pressure has to be at least 50psi at all engine speeds and loads.

http://www.realoem.com/bmw/enUS/show...diagId=13_0900

[Critter7r]

A vacuum leak won't typically cause a single-cylinder misfire.

If the fuel pressure checks out ok, then swap the injector to a new cylinder.

Is it safe to assume you didn't find a bunch of oil in the spark plug hole when you changed the plugs? #6 is the most likely culprit to get filled with oil when there's a valve cover gasket leak.