Cold idle speed.

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lincsmps6
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Joined: November 7th, 2011, 3:06 pm

Cold idle speed.

Post by lincsmps6 »

We all know that our MZR engine has a noticeably high cold idle on 1st start up and that it does sound rather terrible, but wonder how many of us know that it can be 'bypassed' by slightly pressing the throttle as you start the engine. Doing this stops it revving so high, instead it idles around 1300ish (vs nearly 2k) and quickly reduces even further making start up much quieter shall we say.
I was wondering if VT can be used to program it out all together, to remove the need to touch the throttle, because very often I just lean into the car and twist the key before opening my garage doors and locking up etc.
Is this a possibility? I have alter the idle settings on my tune, but cold idle (unless the throttle is touched) is still very high.

Cheers...
mituc
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Re: Cold idle speed.

Post by mituc »

Frankly I'm not really interested in making the car quieter in the first 1-2 minutes after a cold start versus having the oil heated up as much as possible when I leave the parking lot. That high idle rpm is there for a good reason, to provide as much oil pressure as possible when the oil is cold/thick in order to heat it up and to lube as many moving parts as possible (rod bearings, piston rings,valve train, and so on).

However, the cold idle engine speed can be adjusted from the versatuner as well and you can set it to a lower value, but make sure you really know what you're doing.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
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Steve @ VersaTune
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Re: Cold idle speed.

Post by Steve @ VersaTune »

The high idle after startup is mostly for emissions. They want to get the pre-cat up to operating temp as quickly as possible.
mituc
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Re: Cold idle speed.

Post by mituc »

So this means that there's little to no effect on preventing the engine wear? Or does it wear the engine even more?
Because the engine noise is really low in the summer and now in the winter I get off the car 50% of the cases to put my wipers back on, get the snow off the car, and so on.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
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Steve @ VersaTune
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Joined: March 29th, 2010, 12:58 pm

Re: Cold idle speed.

Post by Steve @ VersaTune »

I rebuilt my engine at 75,000 miles. I use Mobil 1 5w30 full synthetic. There were no signs of wear, and the inside of the engine was spotless. If you use good oil of the correct weight, there shouldn't be any concerns. It gets down as low as -10F/-23C in winter where I am.
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richy-m-g
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Re: Cold idle speed.

Post by richy-m-g »

I'm thinking of raising my cold idle speed by 100 rpm or so to help develop more crankcase pressure to ease the oil/turbo seal/white smoke scenario. I notice there are two tables; Idle RPM 1 and Idle RPM 2. Which one is used by the ECU and when?
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richy-m-g
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Re: Cold idle speed.

Post by richy-m-g »

Steve from Versatune has explained that I should enter the same values I want in both Idle Tables.

ALSO where you have MAF Calibration tables 1 & 2, you should make them both the same.
mituc
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Re: Cold idle speed.

Post by mituc »

richy-m-g wrote:I'm thinking of raising my cold idle speed by 100 rpm or so to help develop more crankcase pressure to ease the oil/turbo seal/white smoke scenario. I notice there are two tables; Idle RPM 1 and Idle RPM 2. Which one is used by the ECU and when?
Don't! 1750rpm is already high enough for a cold engine with cold and viscous oil and little to no lubrication in the first 15-20 seconds after starting it.
If you want to prevent your turbo from smoking raise the warn idle rpm from 650 to 800 or so.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
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richy-m-g
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Joined: February 10th, 2013, 6:19 am
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Re: Cold idle speed.

Post by richy-m-g »

Mituc, I am only raising the three cells below 1000 rpm, by 100 rpm or so. From what I've gathered 850 to 1000 rpm is enough idle to help the oil seals all its going to.
Thanks for looking out for me and the rest of us.
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