does cold weather changing the ISF sound？
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Driver School Candidate
Joined: Sep 2013
Posts: 40
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From: texas
does cold weather changing the ISF sound？
some reason i cant hear the beast sound on my isf with sport mode after 3600 rpm. it only come back on when i lower the gear while driving. BUT no sound when go off from red light even i hit 4500 rpm....
Thread Starter
Driver School Candidate
Joined: Sep 2013
Posts: 40
Likes: 0
From: texas
Thread Starter
Driver School Candidate
Joined: Sep 2013
Posts: 40
Likes: 0
From: texas
when go off after red light. if i use sport+manual，i wont hear the beast sound on first gear when the rpm pass 3600. But the beast sound will came back on when i up shift to 2nd.gear.
here is the tricky part.if i just use auto+sport，or just normal auto mode，when RPM hits 3600，i can hear the beast sound clearly， when i go off after red light.
（all these are going from 0MPH）
here is the tricky part.if i just use auto+sport，or just normal auto mode，when RPM hits 3600，i can hear the beast sound clearly， when i go off after red light.
（all these are going from 0MPH）
Pole Position
Joined: Jun 2013
Posts: 298
Likes: 0
From: MA --> CA
I don't drive manual when the car is still cold (I wait until oil temperature is at 2 bars, preferably 3) otherwise the drive is really clunky. It takes almost like a second to shift up and when down shifting it's clunky. Always get the car warmed up before any hard accelerations.
when go off after red light. if i use sport+manual，i wont hear the beast sound on first gear when the rpm pass 3600. But the beast sound will came back on when i up shift to 2nd.gear.
here is the tricky part.if i just use auto+sport，or just normal auto mode，when RPM hits 3600，i can hear the beast sound clearly， when i go off after red light.
（all these are going from 0MPH）
here is the tricky part.if i just use auto+sport，or just normal auto mode，when RPM hits 3600，i can hear the beast sound clearly， when i go off after red light.
（all these are going from 0MPH）
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VVTi is not VTEC or even remotely like it. It "kicks in" all the time. Agree, punishing a cold engine will punish your wallet in the long run for sure.
Pit Crew
Joined: Oct 2013
Posts: 199
Likes: 3
From: Tennessee
The blacktop enigne they are talking about is what I had before. Most of the 4 cylinders work the same way...
Check out this page about 1/2 way down: http://www.billzilla.org/vvtvtec.htm
"There is absolutely NO VVT operation when the coolant tempt is below 50°C except for that brief moment when you operate the starter. Reason obvious, who want to stress a cold engine."
In fact if you check this link it does indeed describe the VVti system on our specific engine: http://www.supra-2urgse.com/?p=66
"Hydraulic VVT-i cannot operate below 1000rpm or when the engine is cold."
Last edited by rmillsISF; Nov 11, 2013 at 10:56 AM.
And that's why I didn't say VTEC - never owned a Honda and don't want one. Not sure if this system works the same way as other Toyota engines on the VVTi system, but most won't activate under certain engine temps.
The blacktop enigne they are talking about is what I had before. Most of the 4 cylinders work the same way...
Check out this page about 1/2 way down: http://www.billzilla.org/vvtvtec.htm
"There is absolutely NO VVT operation when the coolant tempt is below 50°C except for that brief moment when you operate the starter. Reason obvious, who want to stress a cold engine."
In fact if you check this link it does indeed describe the VVti system on our specific engine: http://www.supra-2urgse.com/?p=66
"Hydraulic VVT-i cannot operate below 1000rpm or when the engine is cold."
The blacktop enigne they are talking about is what I had before. Most of the 4 cylinders work the same way...
Check out this page about 1/2 way down: http://www.billzilla.org/vvtvtec.htm
"There is absolutely NO VVT operation when the coolant tempt is below 50°C except for that brief moment when you operate the starter. Reason obvious, who want to stress a cold engine."
In fact if you check this link it does indeed describe the VVti system on our specific engine: http://www.supra-2urgse.com/?p=66
"Hydraulic VVT-i cannot operate below 1000rpm or when the engine is cold."
The variable valve timing system is designed to control the intake and exhaust (on some systems) camshaft(s) to provide valve timing that is optimally suited to the engine conditions. This improves torque in all speed ranges, as well as increased fuel economy and reduced exhaust emissions. Camshaft timing is varied based on engine operating conditions such as intake air volume, throttle position, and engine coolant temperature. The ECM checks the actual valve timing based on input from the camshaft position sensor and the crankshaft position sensor.
There are several types of variable valve timing systems in use on Toyota and Lexus vehicles, including VVT-i, Dual VVT-i, and VVT-iE. It is essential that the VVT system be correctly identified before beginning diagnosis. The best source for identifying the VVT system on a specific vehicle is the Repair Manual.
The VVT-i system phases only the intake camshaft and includes the ECM, the oil control valve (OCV), and the VVT controller (on the camshaft). The ECM controls the OCV duty-cycle, which in turn regulates the oil pressure supplied to the VVT controller. Because the VVT-i system relies on oil pressure to operate, valve timing will not be optimized when the engine is cold or at low engine speeds.
The Dual VVT-i system phases both the intake and exhaust camshafts and includes the same components as the VVT-i on all camshafts.
The VVT-iE system uses electric motors to phase the intake camshafts. The exhaust camshaft is phased using the same components as the VVT-i system. Because the intake camshaft is phased by electric motors, it can optimize valve timing even when the engine oil pressure is low, such as when the engine oil temperature or the engine speed is low.
There are several types of variable valve timing systems in use on Toyota and Lexus vehicles, including VVT-i, Dual VVT-i, and VVT-iE. It is essential that the VVT system be correctly identified before beginning diagnosis. The best source for identifying the VVT system on a specific vehicle is the Repair Manual.
The VVT-i system phases only the intake camshaft and includes the ECM, the oil control valve (OCV), and the VVT controller (on the camshaft). The ECM controls the OCV duty-cycle, which in turn regulates the oil pressure supplied to the VVT controller. Because the VVT-i system relies on oil pressure to operate, valve timing will not be optimized when the engine is cold or at low engine speeds.
The Dual VVT-i system phases both the intake and exhaust camshafts and includes the same components as the VVT-i on all camshafts.
The VVT-iE system uses electric motors to phase the intake camshafts. The exhaust camshaft is phased using the same components as the VVT-i system. Because the intake camshaft is phased by electric motors, it can optimize valve timing even when the engine oil pressure is low, such as when the engine oil temperature or the engine speed is low.
Back to the OP's original question - how does the secondary air inlet work - or why does it not work when the engine is cold? There is nothing in Lexus technical documentation saying anything about engine temperature and the dual mode intake. The ECM has to decide to switch it on, but the programming making this happen is not available to the public, or even to service techs at the dealership level. I would not personally put the crop to a cold engine any more than I would try maximum weight on my first set at the gym. It's really bad for service life and can cause very permanent damage.
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