BMW e39 M5 misfiring

[SHRNTA 48]

Hi All,

just wanted to confirm a "what would you do" situation for me.

Took the M5 for a spin over the weekend and lost power (started to lose responsiveness ie, a bit sluggish) down the motorway after 20 mins of driving.

Came home, put the scan tool in and got a misfiring in "Cylinder 7 with cylinder cutout". I've taken the covers off and noticed that the Bremi ignition coils for cylinder 5-8 were all original (manufactured 12-99). Car has only done 132,xxx ks, spark plugs replaced at 100,xxx ks. I suspect Cylinder 1-4 are also original Bremi (but haven't checked).

Should I just replace all ignition coils? Cylinder 7 coil looked fine, it didn't seem to be bad.

Car is booked in at BM Workshop in a couple weeks (these guys are just super busy). they quoted me Bremi replacement 125 +gst / coil. I'm thinking I just order online for $85/coil and do all myself if it's probably something I need to change anyway (if all original). What mileage should you be expecting to change coils for an e39 M5?

Also I'm getting Oxygen Sensor, bank 1 & 2 error.

Thanks

 

[NZ00Z3 187]

The O2 sensor errors, are they the exceeded tolerance ones.  Meaning that you have a vacuum leak.  If so, find and fix the vacuum leak and the misfire may just go away.

[Gaz 1060]

Pull the coil out of 7 and swap with another cylinder, clear the code and take it for a drive. If the fault follows then replace the coil

[BreakMyWindow 1874]

Any more details around the oxy sensor errors from your scanner ? post cat or pre cat oxygen sensors ? There's 4 in total. Can you post up the errors, and also does your scanner show the additive and multiplicative fuel trims ? These maybe represented by long term and short term fuel trims.

Try unplugging the mafs, go for a drive and see if you're getting the same behaviour. Mafs are a common issue on the s62.

Coils are usually rock solid, mine are all original, and haven't heard of any one in the nz group of owners having to replace them.

[SHRNTA 48]

10 hours ago, BreakMyWindow said:

Any more details around the oxy sensor errors from your scanner ? post cat or pre cat oxygen sensors ? There's 4 in total. Can you post up the errors, and also does your scanner show the additive and multiplicative fuel trims ? These maybe represented by long term and short term fuel trims.

Try unplugging the mafs, go for a drive and see if you're getting the same behaviour. Mafs are a common issue on the s62.

Coils are usually rock solid, mine are all original, and haven't heard of any one in the nz group of owners having to replace them.

I replaced the MAFs last year or so. I will need to look into the oxy sensors, scanner tool is handheld so doesn't give proper error message. will need to check the additive and multiplicative fuel trims.

Will let you know.

[BreakMyWindow 1874]

Did you replace with bosch mafs ?

[SHRNTA 48]

4 hours ago, BreakMyWindow said:

Did you replace with bosch mafs ?

Yup Bosch, replaced by BM Workshop up here in Auckland.

[SHRNTA 48]

For those interested, it ended up being cracked ceramic around spark plug.

replaced all plugs, and it is once again the Ultimate Driving experience.

Now i need to get clear coat on roof issue sorted and replace rubber seals around rear and front windscreens. Any tips?

[lemusa 86]

On 9/11/2020 at 10:28 PM, SHRNTA said:

replace rubber seals around rear and front windscreens. Any tips?

I recently got a front seal here: https://www.fcpeuro.com/BMW-parts/540i/Window-Seals/?year=2003&m=20&e=188&t=5&b=5&d=10&v=

Takes a little muscle to install but the new rubber is very forgiving and looks so much better.