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      04-24-2015, 08:26 AM   #1
Creamo3
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X5M Coldstart RPM - Tunable?

I currently have a Eurocharged tune on the truck and asked if they could lower the coldstart RPM to ~1000 instead of the 1500 it is at now, but they weren't sure if these tables were tunable. So I'm asking the community if they know if these tables are accessible and can be modified. My neighbors would appreciate this when I start my truck in the morning
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      04-24-2015, 11:38 AM   #2
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Not aware u can do that I had option of turning cold start on or off when I loaded my tune
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      04-24-2015, 11:47 AM   #3
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All cars, I mean ALL cars I've ever owned in 20 yrs, have cold start processes that raise the RPM's.

Because the car is cooler or perhaps in a colder climate, the higher RPM is needed to keep the car running.

Don't dismiss a hundred years of combustion engine technology for your neighbor.
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      04-24-2015, 12:33 PM   #4
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Quote:
Originally Posted by mitch808 View Post
All cars, I mean ALL cars I've ever owned in 20 yrs, have cold start processes that raise the RPM's.

Because the car is cooler or perhaps in a colder climate, the higher RPM is needed to keep the car running.

Don't dismiss a hundred years of combustion engine technology for your neighbor.
the cold start function in ONLY for emissions to warm up the cats
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      04-24-2015, 12:37 PM   #5
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Quote:
Originally Posted by infamousdiz View Post
the cold start function in ONLY for emissions to warm up the cats
No, no it's not. At least not primarily.

There are other things in play that address the catalytic. advanced timing, exhaust recirculation, increased fuel injection duration.

raised RPM is for much more than the catalytic. Seriously, if you drop the RPM, the car would probably stumble and stall.
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      04-24-2015, 01:25 PM   #6
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Quote:
Originally Posted by infamousdiz View Post
the cold start function in ONLY for emissions to warm up the cats
Yes this is correct. Your car idles at 1500rpm for ~15 seconds to light off the cats and drops to 1000 and then down to ~600 once fully warm. When I used to tune Evo's I would modify this table for the reason stated above.

Eurocharged got back to me and will have an X5M in the shop in the next 10-days and is going to find the correct table.

Quote:
Originally Posted by mitch808 View Post
No, no it's not. At least not primarily.

There are other things in play that address the catalytic. advanced timing, exhaust recirculation, increased fuel injection duration.

raised RPM is for much more than the catalytic. Seriously, if you drop the RPM, the car would probably stumble and stall.
The car will be fine if it starts at 1000rpm, it's actually offered as an option from ESS on their tunes.
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      04-24-2015, 01:47 PM   #7
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I'm not saying you can't. But it's not as simple as dropping the RPM.

Ever play with a carburetor? Ever had a carbureted engine? Remember that choke switch? Same concept.

Basically, raising the RPM is one of the better ways dealing with the unburnt and poorly atomized fuel at startup.

At startup the car runs richer too, to heat up the catalytics faster, etc.

So simply lowering the RPM is not the right approach. Actually addressing fueling, among other tables will be needed.
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      04-24-2015, 02:05 PM   #8
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Quote:
Originally Posted by mitch808 View Post
I'm not saying you can't. But it's not as simple as dropping the RPM.

Ever play with a carburetor? Ever had a carbureted engine? Remember that choke switch? Same concept.

Basically, raising the RPM is one of the better ways dealing with the unburnt and poorly atomized fuel at startup.

At startup the car runs richer too, to heat up the catalytics faster, etc.

So simply lowering the RPM is not the right approach. Actually addressing fueling, among other tables will be needed.
Yes I agree, most of the cold start sub-routines are most likely driven by RPM & coolant temp. It should be a pretty simple change, at least it used to be for me. I'm not sure if this car transitions from open loop to closed loop to control fuel trims once it's warmed up or if it just starts in closed loop. Timing tables are driven by RPM & calculated load, which should be practically identical for a small 500 rpm increment that low in the rev range. Being that I have to rely on a 3rd party to tune it, I'll let them figure it out.
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      04-24-2015, 07:59 PM   #9
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Quote:
Originally Posted by infamousdiz View Post
the cold start function in ONLY for emissions to warm up the cats
So, what about cars that did this before there were cats?
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      04-24-2015, 08:13 PM   #10
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Quote:
Originally Posted by lanbrown View Post
So, what about cars that did this before there were cats?
What cars are your referring to? Cats have been around since the mid 70's and fuel injection started rolling out in the 80's. Before then it was carb based and didn't require an ECU to control functions like cold start. You had a throttle set screw for setting RPM. With electronic fuel injection and ECUs to control things like throttle position/idle control valves you also had the ability to modify cold start.
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      04-24-2015, 08:30 PM   #11
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Almost any vehicle built before cats were used. When first started, they would have a fast idle before settling down to the normal idle speed. So, the cats cannot be the reason if fast idle existed prior to the introduction to cats.
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