E39 540i Misfire Various Cylinder with Fuel cut.

[HoZy]

Hey all,

Doing my routine scan with BMW Scanner, and we've got quite an interesting & confusing set of codes.

Basically misfire various cylinder & fuel cut on cyl 1, 4, 3, 2.

Now, Cats are fine, 30,000km. Magnaflow 200cell metallic cats & the temps on them are both the same and no abnormal coloring or loss of power etc.
MAF sensor is only a couple of years old genuine bosch unit and I did spray it down and no change.
Coils are 4years old and they are TOPGUN (an australian ignition manufacturer) units. (checked the coil ground wire)
CCV is fine as there is no smoke.
No vacuum leaks that I can find by doing a test, idles smooth cold & hot.

I've had Bank1 & Bank2 Pre-Cat O2 sensor report error for about a year now, however fuel economy & power are un-affected so I've ignored them.

Is there a chance that the O2 sensor for that bank is now f'd beyond all belief causing that set of errors?

All advice & help greatly appreciated.
Cheers
Mat

[lesguy]

Had similar issue on my 540. As a cheap temporary test, bought 8 new offbrand coils on eBay for $85. Put them all in.

That was about two years ago.

Random idle hiccup/misfire never returned.

[redd2k]

I wouldn't think 02 sensors would cause this then again i may be wrong but right now im having the same problem but mine is a very rough idle and the entire drivers side missfiring

[geargrinder]

Easily O2 could be causing. Esp w codes. Engine thinks AFR is good but it's not. DME knows how to validate check O2's using the post O2's and other plausibility patterns. Likely the codes are correct.

Coils I'd leave for a not last but later resort. I haven't had false O2 codes w my bad coils.

[TJ98E39]

Same issue, but I also had valve cover leaks so I'm replacing seals, plugs could and O2, they all need it anyway.

Sent from my SAMSUNG-SM-G891A using Tapatalk

[E39540V8]

Can you move the sensors across to the other side to see if the codes follow?

[ViolinARC]

Can you move the sensors across to the other side to see if the codes follow?

FME, sounds like bad coils to me...agreed that you should move coils 1,2,3,4 to different banks and see if the codes follow. It's a quick and cheap way to narrow down your possibilities.

[HoZy]

Small update,

Coils were switched between banks & the issue stayed at 1,2,3,4.

I've got 2x new NTK O2 sensors on the way to eliminate that.

Cheers
Mat

[HoZy]

Update:

Fitted new NTK O2 sensors & new NGK Iridium plugs as well as fixed a vacuum leak in the intake boot (replaced the boot)

Issue has not returned.

Cheers
Mat

[TJ98E39]

So I fixed my valve cover seals, changed out the coils and plugs. I still have issies with missfire Which O2 sensor did you change out? Looking into more option to fix it.

[TJ98E39]

Update:

Fitted new NTK O2 sensors & new NGK Iridium plugs as well as fixed a vacuum leak in the intake boot (replaced the boot)

Issue has not returned.

Cheers
Mat

Any problems

[HoZy]

Any problems

Not as yet. And I replaced both my o2 sensors. My car only has pre cat o2 sensors.

Cheers
Mat

[TJ98E39]

Ok thanks I'll try that

[ViolinARC]

Update:

Fitted new NTK O2 sensors & new NGK Iridium plugs as well as fixed a vacuum leak in the intake boot (replaced the boot)

Issue has not returned.

Cheers
Mat