07 335i recently bought, #6 misfire, then random misfire, new o2’s, where to start?

[flyingspirit55]

Hello, new to bmw’s, bought car like this, the first step we did was, new battery, put cats, muffler since previous owner took them off, and new secondary o2’s, car starts, sounds like a bucket of bolts but stays running. Initially has code only for #6 misfire then, after a few minutes codes are random misfire 1,3,4,5,6 (not 2?), then p0140 but o2 new secondary voltages are okay but checking on black wire with voltmeter .7mV but rise as we rev the car. But the actron live read it shows .45v b1s2 but .7mV on b2s2. So I don’t know what to make of this. I probably need a better scanner.

I plan to buy a Foxwell nt510 elite, since the abs light comes on during turns and airbag light is also on, looks like a Christmas light special on the dash. This scanner worth it?

no mods on car other than cone air filter, so what should we start with, appears all coils and plugs have been changed (maybe previous owner attempted to fix), I searched online and see air flow/map sensor, vanos sensors and of course #6 injector as possible issues.

Occasionally after a few miles and turning on and off it goes into limp mode. It also backfires on deceleration.

But asking for advice on where to tackle this first.

[jumpmanonlyE92]

Did you check #6 coil pack?

[flyingspirit55]

Yes, it was low compression, sucks. I’ll get around to fixing it in the near future.

[jumpmanonlyE92]

If you looking for an affordable fix, find you a euro only local repair shop. They always work to spec.

[drewusmaximus]

Backfire.., sounds like it's running rich. Check fuel pressure. Might be injector.
Did you look into the spark plug holes? Any oil in there? Are the spark plugs clean or oily?
Low compression.. Is the VCG leaking? Did you check your CCV?
Any air leaks in the intake/boot? Too much air will cause all cylinders to misfire.
Did you check the oil pan gasket?
What color is the coolant?

[flyingspirit55]

#6 has pretty much all of the above, looks like a busted oil ring due to #6 leaky injector. All others clean. Intake gaskets look clean and soft but not too soft. Oil pan gasket leaks. Coolant is perfect.

[drewusmaximus]

#6 has pretty much all of the above, looks like a busted oil ring due to #6 leaky injector. All others clean. Intake gaskets look clean and soft but not too soft. Oil pan gasket leaks. Coolant is perfect.

Oh boy.. I know a guy who dismantled two pistons, slid them to the top, replaced the rings, put on the sleeve and banged it back down, while the engine was still in the car! Reconnected the rods to the crankshaft and buttoned everything up. Engine ran for a long time. How he did it? I have no idea.. Talk about taking shortcuts! lol

[flyingspirit55]

Haha nice.