How to turn off high Rev's on Startup

Mark_BC

Mark_BC

Senior Member
After you start it up the rev's go high for a while until the engine warms up. I find this really annoying sometimes. I yearn for the good ol' days before ECU's when you had to work the pedal to get it going.

Sometimes I want to do compression braking down a hill after I start it up and it's a pain to have to use the brakes to fight both the engine and the hill. I don't want to have to wait 5 minutes for it to warm up.

I doubt I could change the computer programming but maybe there's a way to fool the temperature sensor to make it think it's warm?
 
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I've been thinking the same thing. With the high revs, shifting between "R" and "D" position and seeing how much strain is locked by the brakes could wear the drive train. This is the same thing I am considering to Landcruiser 100. The infamous front drive line clunk in the landcruiser is also due to this high rev at the startup and shifting between D and R.

For the 5VZFE: What if the IAC valve is made to stay closed at all times?

My car which is 4afe 5-speed manual still has the high rev at the startup but with the clutch, I can control the power going into the drive train. I drive off within 2-3 second of starting the engine and the car has 270K miles and does not burn oil, so low revs really not going to hurt the engine, I believe.
 
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I'm all for modding the truck but i'm sorry this one seems silly. x2 on just let it warm up its like a couple minutes. do you really start it and take off instantly down a big hill?

Sorry im no help on this one but warming up is good. worst case down shift.
 
calimobber said:
I'm all for modding the truck but i'm sorry this one seems silly. x2 on just let it warm up its like a couple minutes. do you really start it and take off instantly down a big hill?

Sorry im no help on this one but warming up is good. worst case down shift.
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Sometimes I do start it up and want to go right then. I'm not straining the engine going down a hill. Obviously I wouldn't gun it while it's cold.

Even 1st gear on steep hills is too high when the engine is revving high. It's happened several times now that I wish it wouldn't do this. Not the end of the world, but just one more thing I could tick off a list towards making it an ideal off road vehicle.

Why waste 5 minutes of gas warming it up? What if I really do have to go?
 
Mark_BC said:
After you start it up the rev's go high for a while until the engine warms up. I find this really annoying sometimes. I yearn for the good ol' days before ECU's when you had to work the pedal to get it going.

Sometimes I want to do compression braking down a hill after I start it up and it's a pain to have to use the brakes to fight both the engine and the hill. I don't want to have to wait 5 minutes for it to warm up.

I doubt I could change the computer programming but maybe there's a way to fool the temperature sensor to make it think it's warm?
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Define high idle. I ask because my normal high idle progressed over the years to where cold start idle was 2,000+ RPM's. That was NOT normal.
 
What do you consider to be high revs? Mine will run at 1500-1600 RPMs in neutral or park on a cold start until the temp gauge is around half way. AFAIK, that is considered normal. Sometimes the IAC valve or throttle body can be fouled causing much higher idle RPMs. If yours is out of the norm you should probably consider addressing the source of the high idle first.

Sent from my RS988 using Tapatalk
 
Mark_BC said:
After you start it up the rev's go high for a while until the engine warms up. I find this really annoying sometimes. I yearn for the good ol' days before ECU's when you had to work the pedal to get it going.

Sometimes I want to do compression braking down a hill after I start it up and it's a pain to have to use the brakes to fight both the engine and the hill. I don't want to have to wait 5 minutes for it to warm up.

I doubt I could change the computer programming but maybe there's a way to fool the temperature sensor to make it think it's warm?
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Make sure the AC is off and that you're not in Defrost or Defrost/Mix mode.
 
The reason it has a high idle system that operates when the vehicle is cold is that it won't run at normal idle when it's cold.

You could shorten the warmup time by using a block heater or a incandescent lightbulb in a box under the oil pan.
 
After you start it up the rev's go high for a while until the engine warms up. I find this really annoying sometimes. I yearn for the good ol' days before ECU's when you had to work the pedal to get it going.
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I hate to sound like a hater but damn man I thought this was an April fool's post or something but it sounds like you are serious.

I don't have a link handy to explain to you what is happening but there is a reason the car does this. Every modern gas automobile does I believe. So unless you are smarter than all the other auto manufactures at engine design there is really no point for trying to bypass the cold start cycle.

Sometimes I want to do compression braking down a hill after I start it up and it's a pain to have to use the brakes to fight both the engine and the hill.
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That shouldn't be happening. The idle revs even at a cold start shouldn't be above 1500 RPM ever. And at 1500 rpm you won't be fighting Jack squat with the brakes. Maybe there is something we are missing. What are your idle rpms?
 
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BrianSD_42 said:
I hate to sound like a hater but damn man I thought this was an April fool's post or something but it sounds like you are serious.

I don't have a link handy to explain to you what is happening but there is a reason the car does this. Every modern gas automobile does I believe. So unless you are smarter than all the other auto manufactures at engine design there is really no point for trying to bypass the cold start cycle.
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Yes 100% serious. It does this to warm the engine up and to avoid stalling when cold. They can do it because modern engines have computers. Old ones couldn't do this because they didn't have computers. I prefer the old style of startup. Rather than swapping in a 1HZ engine it would be easier to just try to disable it.

It has nothing to do with me being smarter than Toyota, I just don't like this feature and I believe that I am smart enough to know how to not blow up the engine on startup.
 
BrianSD_42 said:
That shouldn't be happening. The idle revs even at a cold start shouldn't be above 1500 RPM ever. And at 1500 rpm you won't be fighting Jack squat with the brakes. Maybe there is something we are missing. What are your idle rpms?
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I don't know on startup, I'll check. It's high enough to make using compression braking going down a steep hill not feasible. Both 4runners sound the same on startup and always have so I don't think there's any problem.

Idle when warm is 700, but sometimes it goes up to 900 for brief periods, not sure why.
 
Mark_BC said:
They can do it because modern engines have computers. Old ones couldn't do this because they didn't have computers. I prefer the old style of startup..
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Old style carburetor motors also did this. They have a kickdown cable that connects to the choke. Sure you could tap the gas and shut it down early but it still existed.
 
theesotericone said:
Old style carburetor motors also did this. They have a kickdown cable that connects to the choke. Sure you could tap the gas and shut it down early but it still existed.
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Old muscle cars had mechanical and electric chokes. Nothing electronic.
You reminded me of my old chevelle and I remember using the kick down cable.
 
Fern said:
Old muscle cars had mechanical and electric chokes. Nothing electronic.
You reminded me of my old chevelle and I remember using the kick down cable.
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Correct. What I was pointing out is that warming up an engine is nothing new. Carbs used thermostatic springs to accomplish this. It's not a new thing with computers and EFI. It's only harder to defeat.
 
[MENTION=146628]Mark_BC[/MENTION] this is most likely the coolant temp sensor in open loop. The high idle is to help get the coolant up to temp so you have heat faster. I am sure there are other things as well but this is my understanding.

My CTS failed a while back and my idle would always stay high no matter what.
If I unplugged the CTS, the idle would drop to the normal range (closed loop).

There is a video on Youtube where a guy ran a potentiometer to his CTS which he could use to increase or decrease his RPM for different situations. I believe this is what you are looking for.

Hope all is well with you, we are very close to finishing the house. I will have free time after that if you are still keen to wrench together.
 
bentos1 said:
[MENTION=146628]Mark_BC[/MENTION] this is most likely the coolant temp sensor in open loop. The high idle is to help get the coolant up to temp so you have heat faster. I am sure there are other things as well but this is my understanding.
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This, for sure. I believe it is also designed (at least on newer cars) to get the catalytic converters up to temp to operate properly.
 
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