my bmw 135i only one exhaust pipe working when cold start

[jasonlau8023]

Is this normal? Normally the one close to passenger side (the car has dual pipe on driver side)working first, after 1 minute the other one close to driver side started to work. Sometimes you can hear some metal sound then the other one is working.

any ideas? thanks in advance!

[Pig Farmer]

Do a search for "golf tee mod". This will explain what is going on and how you can open up the exhaust flap on the stock axle-back (if you're interested).

[mr.fabulous]

Fritz, again. We went around and around about this on UUC many years ago trying to understand if this was an emissions thing, some sort of performance thing we weren't smart enough to understand, or just an exhaust note/volume thing. Operating parameters if the newer motors are way different than they were 15+years ago, and so who knows. My old E36 had the line disconnected with a screw in it for 15 years. My E82 is as-is from the factory, and I'll agree it sounds odd at start-up. This time around, I'll blame it on Fritz and leave it.

[jasonlau8023]

Thanks guys. Now i know its normal.

[Andrewcoja]

It's a flap that only opens up above 3k RPM. If you pull out the bit of trunk liner behind the driver side tail light and then pull back the liner next to it, you will find a couple wires with a plug you can undo. That keeps the flap open all the time. It's just a noise thing.

[twinboost_MD]

Originally Posted by Andrewcoja

It's a flap that only opens up above 3k RPM. If you pull out the bit of trunk liner behind the driver side tail light and then pull back the liner next to it, you will find a couple wires with a plug you can undo. That keeps the flap open all the time. It's just a noise thing.

You're mixing it up with the 3 series process. You unplug it from the valve itself on the 1 don't get confused OP