Cold start delete... negatives?

[Inferi]

Any harmful mechanical problems or long-term issues with having cold start flashed completely off? Stock dp/cats

[EvilMiyagi]

Big Negative... You don't get to annoy your neighbours anymore

[kevin85]

I thought the purpose of cold start is to warm up the cats faster, so they can properly clean the exhaust gas. I think the only negative is that you will be more harmful to the environment before the cats get to proper op temp?

[Djdnav]

Originally Posted by kevin85

I thought the purpose of cold start is to warm up the cats faster, so they can properly clean the exhaust gas. I think the only negative is that you will be more harmful to the environment before the cats get to proper op temp?

Correct. The substrate material in the cat’s need to be warm to be effective. Cold start is simply a higher idle (and depending on the car, activation of a secondary air injection system) to warm up the cats. If you install catless downpipes, there is no reason to have the feature at all.

[cwazy1]

Cold start also closes exhaust valves upon startup..

[gatorfast]

Originally Posted by cwazy1

Cold start also closes exhaust valves upon startup..

Valve action is separate from the cold start sequence. Even if you have cold start removed, the car will close the valves after starting (unless you have your tuner make it otherwise).

[Tommy L Garage]

If you have a manual the only negative is you’ll have to slip the clutch more to get it going

[Inferi]

So if I have stock downpipes... main issues are it'll have less clean exhaust gases the first few minutes after start and since I have DCT it'll be not as smooth to drive until it warms up a bit? Does BMW's recommendation to drive off right after cold starting still apply after cold start sequence delete or would idling a minute or so after start be beneficial now?

[BIGW0RM]

You might hear a clicking noise until warmed up near top passenger side of motor from some activator gizmo people seem to be bothered by.

[cwazy1]

Originally Posted by gatorfast

Valve action is separate from the cold start sequence. Even if you have cold start removed, the car will close the valves after starting (unless you have your tuner make it otherwise).

This is good to know. I always thought it was the valve actuation that defined cold start!

[Vegetable]

I deleted cold start via BM3 for approx 5,000 miles. I liked the quieter start up better for sure, but smelled gas fumes during cold idling (akin to having cat delete) and the clicking noise from the front passenger side of the car when cold was annoying. So I decided I'd rather annoy my neighbors than myself and turned it back on; they have kids after all, so I figure my car with valves open and cold start activated makes us more than square.

[TurboM]

Originally Posted by Djdnav

Correct. The substrate material in the cat’s need to be warm to be effective. Cold start is simply a higher idle (and depending on the car, activation of a secondary air injection system) to warm up the cats. If you install catless downpipes, there is no reason to have the feature at all.

Timing is retarded quite a bit during cold start to put combustion energy/heat closer to the cats, hence warming them up quicker. For obvious reasons this also increases the noise coming from the exhaust.

[danniexi]

Originally Posted by TurboM

Timing is retarded quite a bit...

that’s a derogatory term. i believe you meant timing is intellectually and developmentally disabled.

[TurboM]

Originally Posted by danniexi

that’s a derogatory term. i believe you meant timing is intellectually and developmentally disabled.

LOL. Locker room talk.