Lowering Cold Start Idle RPM?

[Z2TT]

Hello,

I have a 1g-gte, I know on cold starts ussually it would run faster to get the engine warm quicker, mine idles at about 1500 RPM, my question is, is there any way to lower this to say about 1000 rpm?

Thanks.

[Kedderz]

fool the thermostat to always think the engine is warm thus ecu thinks its warm also?

[MWP]

fool the thermostat to always think the engine is warm thus ecu thinks its warm also?

How has the thermostat got anything to do with how the ECU reads coolant temp?

If you mean fudging the coolant temp sensor, are you seriously suggesting this as a solution?
If so, -ve rep should be awarded.

[Kedderz]

obviously your much more knowledgable than me, feel free to pass the neg rep around. everyone has a learning curve and ill openly admit im still learning.

My theory was based upon the ecu is always thinking warm thus not dialing up the rpm.

[turbo_gze]

If the 1G's got coolant lines going to the throttle body (Normaly two lines) you can block them off to stop it.

But why would you? its only idling at 1500rpm for a few minutes.

["Z" UTE]

Hello,

I have a 1g-gte, I know on cold starts ussually it would run faster to get the engine warm quicker, mine idles at about 1500 RPM, my question is, is there any way to lower this to say about 1000 rpm?

Thanks.

What is your post cold start idle RPM? Is that set too high? if so knock your idle rpm down at the throttle stop.

cheers Chuck.

[Slim]

My 1J will idle at 1700-2000rpm when it's first turned on in the morning. It will run like that for a couple of minutes. When it's warm it'll idle at 650rpm in neutral or a little lower in drive.

I have been wanting to know why it revs so high. I don't like it because when it's dead cold is precisely the time that i want the engine to be taking it easy.

[Vios-GT_07]

4A-Gs will idle high when cold too.. don't see any harm in it, as the ECU is trying to get the engine to warm up quickly when cold.. i'm also assuming when the engine is cold, the ECU is running it rich, with a higher timing advance.. and when pressed hard, will cut the ignition or cause a mis-fire to prevent heavy load / high revs.. then again ignition stuff has the highest load when cold, so i could be mistaken..

[Z2TT]

Isn't there a Cold Start Valve, that injects extra fuel to make it run rich?

Yes where my Idle Control Valve is, there are 2 water lines going to it, and also a pipe that goes from the idle control valve to where the turbochargers are (what does that do by the way?). So should I disconnect these hoses. My Idle Control valve also has a connector attached to it, doesn't it get temp readings from these wires and that's how it regulates the idle RPM?

[Jackel]

mines idles are 2250 when i first start the ngoes to 1500 after about 30 seconds

[woggin]

or you could adjust the idle screw on the AFM!!!

[LeeRoy]

The idle screw determines operating temp idle not cold start idle.

[pato]

i dont understand why u want to lower it ?
iam sure the engineers at toyota knew what they were doing when they set it at this,

ummmm, if u really have to, and i cant remember if the 1g's have them, u can remove the iscv, hence practically illiminating the cold start feature, and set the idle with the screw on the trottle body.

this will cause an increadibly low cold start idle ( possibly have to hold foot on accell to keep it goin ) my iscv fucked up on my 1jz, so i took mine out and this is the result.

[JZA70 R]

ill tell you why a lot of people hate the screaming cold start, its because older engines like mine will rattle their tits off for a few seconds during that initial rpm spike, all because the oil pump has barely had enough time to deliver oil pressure. Its the worst timing possible to spike the revs (when you have no oil pressure) and the noise is unbarable.

This guy might not be experiencing this but i know its still an annoying thing to happen (the rpm shoot up). Typical trait of the stock ecu.

ive found three ways around this problem.
1. - I had my alarm installed so i can still crank the motor when the alarm is active, so i get in the car and crank the motor for 5 seconds until i get oil pressure, then i deactivate the immobiliser and fire the engine. I still get the rev spike but no rattles cause ive got pressure.

2. - Buy programmable management. The rpm spike can be calmed a bit by tuning your cold start properly. Factory ecu cold starts are a joke (shits black fuel out on your driveway = way too rich).

3. DIY restrictor on the ISCV. What happens is when you cold start, the ecu opens the ISCV wide open to allow the motor to gulp a huge amount of air which is why it revs up like that, under normal driving conditions the ISCV is open a small amount to allow the idle to be controlled, you can put a restrictor on the ISCV so it cant gulp that huge amount of air initially, but there is still enough air allowed once the engine is warm, for the idle to be smooth and consistent and even for the a/c to be run.

The 3rd solution is easiest and most effective. If you know how.

[JustCallMeOrlando]

It's functioning correct, why would you want to change it? It's supposed to idle that high, it's why it does it.