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okie dokie i know about the DIY VTEC light and how it turns on at 3000rpm. but then i read somewhere a LONG time ago that the engagement point the light gives off was just the signal being sent from the computer and that the ACTUAL 9V signal that actually tells the engine to switch over to the high cam profile ocurrs at the peak toruqe range (around 4500 rpm). is that line tappable for like, a more accurate notification of the engagement point?

does anyone remember this little dispute?

 
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It's true. The signal is sent at 3k rpms, but other factors are needed for actual engagement like 100% throttle, warm engine, enough oil pressure, over 4500rpms, etc.

 
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so the vtec light is worthless

 
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yea even the one on the vafcII which works the same way. On older civics it was different.

 
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so based on that little list (i know theres other factors), i tseems as if oil pressure is one of the more important factors. is there an electrical signal sent to trigger the engagement when enough oil pressure is attained (like is there an oil pressure signal line i can tap?)

and if there is one, would the engagement be set if enough current is flowing through the signal?

 
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Well I think the most important is throttle. At full throttle, a 12v signal is sent to activate the cam change. This is the only factor that changes assuming the car is warmed up and functioning properly. The vafcII senses the throttle position, so I know there is a wire for it on the ecu (check the vafcII faq in tech forum).

 
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aite i found what i was lookin for in that DIY. thanks a lot gearbox!

 
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clarification: are you absolutely sure that this signal (pin #15 red/blk-Throttle position sensor) is sent ONLY at WOT? or is it a signal that increases voltage or amperage or whatever as the throttle increases?

 
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I think it increases as the throttle does, until full throttle when it reaches 12v and actives the solenoid.

 
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Check the voltage at the VTEC solenoid. There is only one wire.

 
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wait, im not looking for total accuracy, but this light isnt going to kick on when vtec is not actually engaged will it? I know there is some lag time inbetween, but its pretty close, so it will light up then a second or two later vtec will kick in?

 
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bump, anyone?

 
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i would try to tap into the vtec soloid... best bet. Check the voltage on it with a multimeter and tell us how it goes ( kinda hard to do while driving but run a wire inside ur car )

 
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hold on.... so i spent a whole $5 in parts, and a 1/2 hour of my life to put a vtec light in my car for no reason???

 
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some what..

 
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correct, but it looks cool right

 
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hell yeah

 
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so this wire is just the portion of the vtec system that tells the ecu when the car is doing over 3K rmps?

 
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yes. Although the light comes on around 3k, and is variable depending on throttle position or rpms (or both), certain other safeguards prevent vtec from engaging. If the car is not warmed to temp, or the oil pressure isn't high enough, or the tps doesn't see WOT (wide open throttle-floored gas pedal), vtec won't engage. This was tested by a member using a data logger. They found that vtec would not engage unless the pedal was floored and rpms were hi (4000+rpms) to give the proper oil pressure.

 
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So the wire sends a signal when vtec is (or is going to) engage? It's not going to light up when vtec is not going to engage is it?

 
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When the tps senses full throttle, it sends a 12v signal to the solenoid that activates the cam switch. When the light is off or in low cam mode, it means vtec isn't on. But having the light on doesn't always mean vtec is on.