[NoMechanicMatt]

I recently purchased my 2018 BMW m240i with 41,000 miles from an auction with a series of problems.

The car had bullet damage that caused multiple malfunctions including not receiving the correct rear wheel speed code.

The car starts fine, with no rough idle or power loss, but white smoke comes from the exhaust on start-up. Oringinally I suspect the pcv or valve cover to be faulty and had them replaced. The smoking stopped for a day but the next morning it started smoking again after a cold start. There are no codes that pop up besides P15DC and P15C8 which is for the rear wheel speed sensor.

Should I go for a pcv delete? Or suspect that it is a possible head gasket or piston ring damage?

With the rear wheel sensor, I have replaced the abs sensor and still have the same codes. Should I suspect I have a bad wiring harness?

I have spent countless hours trying to fix this nightmare, any help is greatly appreciated.

[n55david]

Originally Posted by NoMechanicMatt

I recently purchased my 2018 BMW m240i with 41,000 miles from an auction with a series of problems.

The car had bullet damage that caused multiple malfunctions including not receiving the correct rear wheel speed code.

The car starts fine, with no rough idle or power loss, but white smoke comes from the exhaust on start-up. Oringinally I suspect the pcv or valve cover to be faulty and had them replaced. The smoking stopped for a day but the next morning it started smoking again after a cold start. There are no codes that pop up besides P15DC and P15C8 which is for the rear wheel speed sensor.

Should I go for a pcv delete? Or suspect that it is a possible head gasket or piston ring damage?

With the rear wheel sensor, I have replaced the abs sensor and still have the same codes. Should I suspect I have a bad wiring harness?

I have spent countless hours trying to fix this nightmare, any help is greatly appreciated.

Likely there is damage to wiring or a connector etc.. you'll either need to get an ohm meter and start diagnosing or just start replacing stuff..

As for the smoke.. if it is the pcv, it's because you let it idle too long and it happened again. It could also be a turbo issue as well. However, if replacing the pcv diaphragm fixes the problem for a day then that's likely the problem etc. It's $20 or so to get a new diaphragm and cap. Replace just that and if it fixes it, then you know it's that. It's on you if it happens again because you're letting it happen etc. I would spend the money to try that and if it fixes it, sure do a delete.

[NoMechanicMatt]

I’ve heard that excessive idling b58 is detrimental to the car, so I don’t idle it for more then I have to.

A bullet had ripped through the wiring harness in the back seat. I spent $3200 for the dealership to fix the issue, but still could likely be the problem.

I will get the new PCV ordered today.

Do you have a preferred OHM meter?

[NoMechanicMatt]

There is also a little bit of oil in the intake. Is that normal?




Pictures of before and after wiring harness repair.

[n55david]

Oil in the intake could be from the pcv..

Yeah.. it could be anything with it being electrical. You could have a bad sensor too or even just a blown fuse.

[M3SQRD]

Oil in the intake could also be from a failing turbo.

[ZXMarine72]

That amount of oil in the intake is completely normal on the stock PCV system. That's why it's best to just delete it all together. It will keep things a lot cleaner and save you the trouble of ever worrying about the PCV system again.

[NoMechanicMatt]

Any tips to installing a new pcv? I previously installed one before but not sure if i should use a gasket sealer to insure a secure seal?

[Dom147]

See Kern417's video on it on youtube. Has plenty of great tips for the installation.

[NoMechanicMatt]

installed new pcv start up was fine. Everything seemed normal till I took it on a test drive. Drove it for maybe 5 minutes. Waiting at a stop light car started to shake and when the light turned green I lost lots of power and the exhaust started to chop. my check engine light also turned on stating a 6 cylinder misfire. I turned the car off and on again and when I turned back on the car sounded very rough with a lot of backfire out the exhaust, but no smoke, yet.... Any ideas anyone???

The previous times before the pcv replacement the car started fine, no chop or loss of power, just smoke coming out the exhaust.

[n55david]

Originally Posted by NoMechanicMatt

installed new pcv start up was fine. Everything seemed normal till I took it on a test drive. Drove it for maybe 5 minutes. Waiting at a stop light car started to shake and when the light turned green I lost lots of power and the exhaust started to chop. my check engine light also turned on stating a 6 cylinder misfire. I turned the car off and on again and when I turned back on the car sounded very rough with a lot of backfire out the exhaust, but no smoke, yet.... Any ideas anyone???

The previous times before the pcv replacement the car started fine, no chop or loss of power, just smoke coming out the exhaust.

You had the valve cover off didn't you?

[NoMechanicMatt]

I don't quite understand what you mean by that. I replaced the valve cover, yes I had to remove and replace the seal and reinstall, so the valve cover was off at one point.

could it possibly be my fuel injectors?

[n55david]

Originally Posted by NoMechanicMatt

I don't quite understand what you mean by that. I replaced the valve cover, yes I had to remove and replace the seal and reinstall, so the valve cover was off at one point.

could it possibly be my fuel injectors?

You likely have a vacuum leak