Cold Start w/MPE and CAN Flap Question

[M-gineering]

So I have the MPE and recently installed the Burger CAN flap module in the hope that the car would sound like it does on cold start all the time....it doesn't...

What am I missing? The car sounds insane for a minute or two, then it quiets down and the flaps are open. Its such a drastic change that I can't imagine its all from components heating up so looking for some info/advice...I didn't see a post on this exact issue, but apologize in advance if this has been beaten to death! thanks!

[gthal]

Originally Posted by M-gineering

So I have the MPE and recently installed the Burger CAN flap module in the hope that the car would sound like it does on cold start all the time....it doesn't...

What am I missing? The car sounds insane for a minute or two, then it quiets down and the flaps are open. Its such a drastic change that I can't imagine its all from components heating up so looking for some info/advice...I didn't see a post on this exact issue, but apologize in advance if this has been beaten to death! thanks!

I thought it had something to do with the waste gates closing... could be completely wrong.

[Siciliano611]

GOLFFRR apparently "possibly" figured out a way to trick the car to get rid of it if you have the BMS CANflap module or MS EVC, if you get in the car and turn on accessories (not engine) and then open the valves and then close them...THEN start the car, it won't cold start...wonder if this trick works consistently though

[Dethsupp0rt]

He doesn't want to get rid of the cold start, he wants the car to sound like it does on cold start all the time.

At cold start, the wastegates are open and the engine will run a little "rough" due to a lean condition and ignition timing being pulled in order to warm up the cats.

After the cats are warmed up, everything goes to normal and the engine runs smoother (thus quieter).

I'm told the car is still quite loud from the outside with the valves open. It doesn't sound like it from the driver's seat (I even have active sound turned off). However, it certainly isn't going to be as loud as it is at cold start. I can feel my neighbors' looks in the morning when I fire it up.

[M-gineering]

Originally Posted by Dethsupp0rt

He doesn't want to get rid of the cold start, he wants the car to sound like it does on cold start all the time.

At cold start, the wastegates are open and the engine will run a little "rough" due to a lean condition and ignition timing being pulled in order to warm up the cats.

After the cats are warmed up, everything goes to normal and the engine runs smoother (thus quieter).

Aha..so the Cats are ruining my days...I was hoping that the CAN flap would take care of this...it would be awesome to have that noise on-tap...I'd remove the cats but its nice to make things quiet for the police and other times..any other thoughts on this? Thanks for the info!!!

[AlterZgo]

Originally Posted by M-gineering

Aha..so the Cats are ruining my days...I was hoping that the CAN flap would take care of this...it would be awesome to have that noise on-tap...I'd remove the cats but its nice to make things quiet for the police and other times..any other thoughts on this? Thanks for the info!!!

Not the cats. It's the wastegates closing that is ruining your fun. Wastegates open and dumping boost = car is running in naturally aspirated mode = car is much louder.

Of course, if your wastagates were always open, your car would have zero boost and would feel like a non-turbo M4 = no fun at all either.

Vishnu Tuning's Procede for the E9x had a NA mode for one of their maps that kept wastage's open and made the car sound much meaner. It would be great if BMS or another tuner could implement something similar so we can drive around and annoy the shit out of our neighbors and the public at large.

[M-gineering]

Originally Posted by AlterZgo

Not the cats. It's the wastegates closing that is ruining your fun. Wastegates open and dumping boost = car is running in naturally aspirated mode = car is much louder.

Of course, if your wastagates were always open, your car would have zero boost and would feel like a non-turbo M4 = no fun at all either.

Vishnu Tuning's Procede for the E9x had a NA mode for one of their maps that kept wastage's open and made the car sound much meaner. It would be great if BMS or another tuner could implement something similar so we can drive around and annoy the shit out of our neighbors and the public at large.

Of course! I wasn't thinking it through...been stuck working on Teslas too long lol. I'm with you, it would be nice to have control of this, just for when cruising around town, stuck in traffic, etc...and my neighbors deserve it!!!

[Mike@N54Tuning.com]

Originally Posted by M-gineering

So I have the MPE and recently installed the Burger CAN flap module in the hope that the car would sound like it does on cold start all the time....it doesn't...

What am I missing? The car sounds insane for a minute or two, then it quiets down and the flaps are open. Its such a drastic change that I can't imagine its all from components heating up so looking for some info/advice...I didn't see a post on this exact issue, but apologize in advance if this has been beaten to death! thanks!

The loud cold start comes from the DME injecting extra fuel while the o2 sensors are heating up to warm up the cats faster. Of course if the cats are missing then it gets even that much louder. Once the o2 sensor is warm then the DME shuts off the mode so you can only get it when the car is actually cold.

Mike

[hdekerme]

Once the wastegates close after the car is warm, there is a subtle constant whistle noise coming from the engine bay I think. Anyone else experience this? How do you get rid of it?

[rr006rbc]

I don't think it's healthy for the car to have it running in open loop all the time. It's going to wear out all the oxygen sensors, catalysts, etc way too prematurely. Just get a louder exhaust and remove the secondary cats/resonators.

[hdekerme]

Originally Posted by rr006rbc

I don't think it's healthy for the car to have it running in open loop all the time. It's going to wear out all the oxygen sensors, catalysts, etc way too prematurely. Just get a louder exhaust and remove the secondary cats/resonators.

Some of the aftermarket exhausts don't have cats or valves at all. Isn't that the same thing as disconnecting the valves