Disable high Rev cold start

[Raven604]

Is it possible to disable the ~1500 idle cold start. It's loud as Fuck and if you start moving a few feet right after a cold start and stop, the idle goes back down to normal 700/800 ish anyways.

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[Turdinator]

With a tune it is. I believe the OFT has it reduced in their off the shelf tune and I am positive any competent tuner using Ecutek, BRZedit or any other tuning solution could do it also.

[FT-86 SpeedFactory]

We do it in some of our Stage 2 tunes.

[dem00n]

But that's what makes cold starts fun...

[InvalidJohnny5]

I'd leave it as it is...you risk damaging the engine without a proper warming. Just saying.

[Clipdat]

I'm not so sure about this statement. I believe I have read elsewhere on the forums that the only point of the overlap/high idle upon cold start is to kick start the CATs to reduce pollution and meet emissions requirements.

Without this behavior hard coded into the stock ECU flash, the car would start up and have a natural high idle for a period of time, and then slowly drop - much like almost every other car on the road.

I've personally noticed that on super cold starts (around 30 degrees F), the high/overlap idle will do it's thing and then stop, but the idle will still stay high for another minute or two before finally dropping down.

I'm torn on it though myself. Part of me would want to turn it off so my early morning weekday starts aren't so obnoxious and neighbor-waking, but part of me likes how loud and crazy it sounds... because racecar

Originally Posted by InvalidJohnny5

I'd leave it as it is...you risk damaging the engine without a proper warming. Just saying.

[Raven604]

Originally Posted by InvalidJohnny5

I'd leave it as it is...you risk damaging the engine without a proper warming. Just saying.

Maybe if you peel out of your driveway... But cruising you shouldn't damage anything...

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[KVDB31]

Can the Unichip / Flux2 do anything about changing the cold idle level?

Maybe @Unichip Jack could chime in here?

[ncmx5]

Because Race Car

[PSJohnDoe]

Originally Posted by KVDB31

Can the Unichip / Flux2 do anything about changing the cold idle level?

Maybe @Unichip Jack could chime in here?

I don't think so, the Unichip doesn't get input from the ECU. Without talking to the ECU it has no way of knowing why it is at that RPM, for all it knows, you're coasting. The only things it can detect are throttle position, timing/cam position, and air flow.

[FR-S Matt]

It's there to get the liquids up to operating temperature and warm the cat up before taking off. I always sit for the full time when its cold outside. It's an extra 30 seconds. I also put a quieter exhaust on with my catless header so I'm not a jerk in my apartment complex. Even then, my car is still fairly loud cold start.

[wparsons]

Originally Posted by FR-S Matt

It's there to get the liquids up to operating temperature and warm the cat up before taking off. I always sit for the full time when its cold outside. It's an extra 30 seconds. I also put a quieter exhaust on with my catless header so I'm not a jerk in my apartment complex. Even then, my car is still fairly loud cold start.

Originally Posted by InvalidJohnny5

I'd leave it as it is...you risk damaging the engine without a proper warming. Just saying.

There's two levels of the cold start program.

1) Higher revs, and tons of valve overlap. This is WAY louder. After a few seconds the revs stay up but it's much quieter when the ECU scales back the overlap. This is 100% to get heat into the cats faster. I would have zero issue disabling the overlap part (or minimizing it), it's bordering on obnoxiously loud for no good (to me) reason.

2) Normal higher revs, normal valve overlap. This is the part meant to get heat into the fluids. I wouldn't want to get rid of this.

Originally Posted by Clipdat

I'm not so sure about this statement. I believe I have read elsewhere on the forums that the only point of the overlap/high idle upon cold start is to kick start the CATs to reduce pollution and meet emissions requirements.

Without this behavior hard coded into the stock ECU flash, the car would start up and have a natural high idle for a period of time, and then slowly drop - much like almost every other car on the road.

I've personally noticed that on super cold starts (around 30 degrees F), the high/overlap idle will do it's thing and then stop, but the idle will still stay high for another minute or two before finally dropping down.

I'm torn on it though myself. Part of me would want to turn it off so my early morning weekday starts aren't so obnoxious and neighbor-waking, but part of me likes how loud and crazy it sounds... because racecar

^^ This guy gets it!

[FR-S Matt]

I think the best way to look at this is simple. Drive the car easy until fluids are warm. Most people don't wait once they start their car and take off before the cats have a chance to warm up.

Even with the loudness on the cold start, I kept it with my 3" exhaust. Sure, it was brutal, but I didn't care, lol. No complaints from the apartment complex!

[mad_sb]

Originally Posted by wparsons

There's two levels of the cold start program.

1) Higher revs, and tons of valve overlap. This is WAY louder. After a few seconds the revs stay up but it's much quieter when the ECU scales back the overlap. This is 100% to get heat into the cats faster. I would have zero issue disabling the overlap part (or minimizing it), it's bordering on obnoxiously loud for no good (to me) reason.

2) Normal higher revs, normal valve overlap. This is the part meant to get heat into the fluids. I wouldn't want to get rid of this.



^^ This guy gets it!

I will look at my logs in a bit for overlap and throttle angle but, a big component is the afterstart timing. The default after start timing is -15, when the high cold start idle drops the timing does back to the normal +13 - +15 degrees... this is easy enough to edit and does change the noise level but it also creates stability issues for the idle system and can throw numerous codes.

I'l still messing with it. at one time i had set the after start timing to 0 and it would throw an ignition timing out of range code or somethings like that but it was a lot quieter.. The idle rpm also went up. at the time i was not messing with the idle speed tables.