[herffstyle]

Hi, I have a 2008 335xi, I'd like to disable the cold start process.
I believe the only thing it really does is run rich to warm up the cats quickly.
My car specifically runs the fuel pressure at 2800 psi. And closes the sound flap.
I have tunerpro but have not found a specific cold start option to disable.
My reason is, the car runs like crap until it gets out of cold start.
Has anyone done this?
Thanks
Steve

[uniter]

Originally Posted by herffstyle

Hi, I have a 2008 335xi, I'd like to disable the cold start process.
I believe the only thing it really does is run rich to warm up the cats quickly.
My car specifically runs the fuel pressure at 2800 psi. And closes the sound flap.
I have tunerpro but have not found a specific cold start option to disable.
My reason is, the car runs like crap until it gets out of cold start.
Has anyone done this?
Thanks
Steve

You want your car to do this.

[pwr hungry]

United +1

[uniter]

You can pull the flap control cable out and it won't do it any more. Everything else is necessary. Everything should calm down nice and quick for you.

[3000GT MR]

Eh I beg to differ. A small increase to maybe 1k falling to idle within 30-45 seconds would be ideal. This is usually for emissions and Cat warm up. I've also read it helps keep pistons and chambers clean by allowing the fuel to touch components and get knocked off before it gets warm and baked on.

[herffstyle]

So when in the cold start mode, i get really bad misfires, The motor shakes, it smokes like its a diesel, and takes 10 mins to clear out the cats. I think the injectors are leaking and the 2800psi of cold start makes it worse, i need to take the injectors out and have them cleaned, but its sooo cold outside I thought if i disable Cold Start mode i would be able to at least run it thru the winter before i have to freeze my ass off working on it.
That's why i want to disable it.
So my question still stands>> has anyone done it?

[3000GT MR]

Originally Posted by herffstyle

So when in the cold start mode, i get really bad misfires, The motor shakes, it smokes like its a diesel, and takes 10 mins to clear out the cats. I think the injectors are leaking and the 2800psi of cold start makes it worse, i need to take the injectors out and have them cleaned, but its sooo cold outside I thought if i disable Cold Start mode i would be able to at least run it thru the winter before i have to freeze my ass off working on it.
That's why i want to disable it.
So my question still stands>> has anyone done it?

To answer your question no, as far as we know no one has done it. I'll look at a rom later and see if i can find something

[nanceman]

Yes it's good for emissions, but it's also highly recommended for a powertrain longevity standpoint.

I won't delve into the engineering unless someone asks for me to back it up, but it basically boils down to the fact that the less time your engine spends in non optimal operating temps the less time the engine spends with non optimal tolerances, non optimal fluid viscosity, etc. The quicker your engine get to those operating tolerances the better.

For an extreme example, there's a reason they prewarm the fluids and block in an F1 car before they even start the engine.

[3000GT MR]

Originally Posted by nanceman

Yes it's good for emissions, but it's also highly recommended for a powertrain longevity standpoint.

I won't delve into the engineering unless someone asks for me to back it up, but it basically boils down to the fact that the less time your engine spends in non optimal operating temps the less time the engine spends with non optimal tolerances, non optimal fluid viscosity, etc. The quicker your engine get to those operating tolerances the better.

For an extreme example, there's a reason they prewarm the fluids and block in an F1 car before they even start the engine.

F1 is comparing apples to oranges. Your talking hundreds of different materials with who knows how many different and close tolerances.

Cars don't require a "warm up" and if they are so concerned about fluids and tolerances they wouldn't rev a cold engine up to 1500rmp to warm it up.

Piston engine acft engines require warm up before any type of throttle advancement and they use straight weight molasses

[herffstyle]

Originally Posted by 3000GT MR

To answer your question no, as far as we know no one has done it. I'll look at a rom later and see if i can find something

Thanks man!

[alexwhittemore]

Originally Posted by 3000GT MR

F1 is comparing apples to oranges. Your talking hundreds of different materials with who knows how many different and close tolerances.

Cars don't require a "warm up" and if they are so concerned about fluids and tolerances they wouldn't rev a cold engine up to 1500rmp to warm it up.

Piston engine acft engines require warm up before any type of throttle advancement and they use straight weight molasses

you guys are arguing to the same point. It's absolutely correct that a warm engine operating at nominal dimension and tolerance is less prone to undesirable ill-effects than one operating out-of-spec. If I design a sump pump to work on 220V, bad things will happen if I run it on 110, the best being that your house floods slowly (pump can't move as much water), and the worst being that it floods quickly (the pump can't move any water at all). The same is true of the engine - if I've designed it to run at 190F, it's not going to run well at not-190F.

The point is, you don't need to take precautions to warm up your engine because the engineer has already made the assumption you won't and designed accordingly. The engine has a cold start procedure because a very smart person decided that was better for it than it not having a cold start procedure. That's the very point.

[Dave W.]

I'd recommend that you fix your misfire issue. It's generally a bad idea to mess with the stock tune just to fix a mechanical problem.

With that said, one of the reasons the engine has no power for the first 30 seconds after a cold start is because of VANOS tables. During a cold start the exhaust cam is severely advanced to send hot combustion straight out of the exhaust, lighting off the cats quickly. If the cats didn't get hot early they would be more likely to foul from the extra fuel needed to run a cold engine.

[JamesM3M5]

Epic Motorsports can probably do it. http://www.epicmotorsports.com. But you'll have to buy his tune.

I'd fix the injectors before trying to band-aid it by deleting cold start.

[marcvtec]

Can I boost 18 psi from a cold start. No. Hmmmm there is a reason.

[V8bait]

Cold start enrichment maps aren't in the definitions yet because nobody has cared to find them/tried to find them yet. So you're out of luck in the stock DME for the time being. There's probably around 1,000+ more tables nobody has cared/tried to find yet. Including some somewhat important ones, but I digress.

Rest your mind, cold start enrichment isn't just for emissions to heat up the cats. I'll sum it up for you here briefly- Liquid fuel doesn't burn, it has to be a gaseous MIXTURE of fuel/air. It takes HEAT to vaporize liquid fuel (yes, even in DI), the compression won't do all the work for you. By injecting MORE fuel, you get a greater chance of getting fuel into the gaseous phase. If you think it runs bad now, just wait 'til you lean it out some on a -20 day :-)

Source: tuning cars on a stand alones in Colorado

[herffstyle]

Has anyone ever come up with a way to remove the cold start routine?

[Sered]

This is an old thread. MHD has a checkbox option when flashing that turns it on/off.

[V8bait]

Yep over time more tables will be defined. A big one for cat warmup was released and can be modified at flash time or in the bin directly, it shuts up the car when you try to leave your neighborhood early in the morning without cats. Additional cold start enrichment tables are still undefined but would be nice for those running e85, someday maybe.