Throttle Body Coolant Passage
02-15-2008, 10:00 AM
#24
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it's designed for cold starts only.
when cold it allows air to bypass the TB and enter directly into the intake manifold for a smoother idle. it also at the same time heats the air as the coolant passes through the ISC valve. Once a certain temp is achieved (70°F), the spring in the air valve closes and then it sits and does nothing.
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02-15-2008, 10:56 AM
#25
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Seeing as how multi-cylinder motorcycles dont have anything for idle control, and they still do idle pretty decently (that too on a crazy cam with ITB's), I'm wondering how important the IAC valve is on a performance-oriented vehicle.
Anyone disconnected the IAC valve? Or not controlling one on their MS setup? It would make the coldside piping SO much more easier.
EDIT: I just realized you can add a small air filter to the IAC hose instead of hooking it up to the coldside piping. Specially if you have a MAP sensor.
Anyone disconnected the IAC valve? Or not controlling one on their MS setup? It would make the coldside piping SO much more easier.
EDIT: I just realized you can add a small air filter to the IAC hose instead of hooking it up to the coldside piping. Specially if you have a MAP sensor.
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02-16-2008, 02:17 AM
#31
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Same thing you call air valve - there is some wax in it which expands from the hot coolant.
On a NA8 it is part of the ISC and you can't just unbolt it like on a NA6. You have to unbolt the ISC, pour some gasket maker in wax valve's air channels (but be careful not to plug the idle solenoid) and leave it for few days to dry out. If one doesn't do this but just disconnects the coolant lines from the NA8 throttle body, he ends up with quite a random idle gremlins depending on things like the ambient air temp ...
On a NA8 it is part of the ISC and you can't just unbolt it like on a NA6. You have to unbolt the ISC, pour some gasket maker in wax valve's air channels (but be careful not to plug the idle solenoid) and leave it for few days to dry out. If one doesn't do this but just disconnects the coolant lines from the NA8 throttle body, he ends up with quite a random idle gremlins depending on things like the ambient air temp ...
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02-16-2008, 05:07 AM
#32
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Oh you've got to be kidding me.
I pulled the coolant lines on my NA8 forever and a day ago, it's had some funky idle issues (mainly whenever i hit the brake). All I did was pull the lines and cap the holes. Any guidance on what passages i need to block on my NA8? This is the first I've ever heard of such a thing; all the passages looked like there was nothing to worry about in them.
I pulled the coolant lines on my NA8 forever and a day ago, it's had some funky idle issues (mainly whenever i hit the brake). All I did was pull the lines and cap the holes. Any guidance on what passages i need to block on my NA8? This is the first I've ever heard of such a thing; all the passages looked like there was nothing to worry about in them.
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02-17-2008, 02:02 AM
#33
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Oh you've got to be kidding me.
I pulled the coolant lines on my NA8 forever and a day ago, it's had some funky idle issues (mainly whenever i hit the brake). All I did was pull the lines and cap the holes. Any guidance on what passages i need to block on my NA8? This is the first I've ever heard of such a thing; all the passages looked like there was nothing to worry about in them.
I pulled the coolant lines on my NA8 forever and a day ago, it's had some funky idle issues (mainly whenever i hit the brake). All I did was pull the lines and cap the holes. Any guidance on what passages i need to block on my NA8? This is the first I've ever heard of such a thing; all the passages looked like there was nothing to worry about in them.
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02-29-2008, 10:57 PM
#34
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it's designed for cold starts only.
when cold it allows air to bypass the TB and enter directly into the intake manifold for a smoother idle. it also at the same time heats the air as the coolant passes through the ISC valve. Once a certain temp is achieved (70°F), the spring in the air valve closes and then it sits and does nothing.
Although, in my scenario, it doesn't make sense why my idle jumps up since I'm not using the air valve or the IAC. Idle is controlled with the TEC3 -- I need to play with the maps so warm idle doesn't go crazy like that.
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03-02-2008, 01:30 AM
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With most standalones you can control the idle with ignition timing rather than an ISC.
I can't speak for MS, but my DSM runs an Autronic SMC and the ISC is removed with the passages blocked. I want it to idle at 1000RPM, so I set the idle ignition timing (when TPS is less than 2%) to 25deg at 850, and 0deg at 1100. Then adjust the throttle stop (or the idle air screw) until it idles at 1000 with 1 or 2 degrees of advance. When it's cold I have to hold open the throttle for a couple minutes until it gets some heat into the motor or it'll die. After that it's fine. You'll probably have to play with the fueling a bit to get a smooth idle at 0deg advance.
I can't speak for MS, but my DSM runs an Autronic SMC and the ISC is removed with the passages blocked. I want it to idle at 1000RPM, so I set the idle ignition timing (when TPS is less than 2%) to 25deg at 850, and 0deg at 1100. Then adjust the throttle stop (or the idle air screw) until it idles at 1000 with 1 or 2 degrees of advance. When it's cold I have to hold open the throttle for a couple minutes until it gets some heat into the motor or it'll die. After that it's fine. You'll probably have to play with the fueling a bit to get a smooth idle at 0deg advance.
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03-02-2008, 11:49 AM
#38
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EGT at idle is fine, around 900F.
Even WITH the ISC, my miata idles at ~5deg so I can have the throttle-plate open as far as possible for anti-lag use. Same story there, less than 1000F idle. However if you kick on the ALS (-30deg advance), it'll peg the EGT gauge if you don't watch it
Even WITH the ISC, my miata idles at ~5deg so I can have the throttle-plate open as far as possible for anti-lag use. Same story there, less than 1000F idle. However if you kick on the ALS (-30deg advance), it'll peg the EGT gauge if you don't watch it
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03-02-2008, 01:31 PM
#39
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I have it plugged just like braineack is doing and I passed california state emmissions on the oem ecu. The main problem is it wants to idle very low when the car is cold, so i backed out the screw a few turns until the car was warm.
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