My friend has a 96 civic cx, and his motor went bad so he bought a replacement motor at hmo, but I notice he got a d15b 3 stage vtec, I'm aware of what it is and all that fancy information, the question I have is, we are planing on using a p2p ecu and wired up the vtec stuff just like if we were doing just a d16y8 swap, but the p2p ecu obviously doesnt automatically work with the 3 stage vtec, so for the second solenoid i was planning on connecting it straight to a switch, reason why is because as I read the p2p ecu will work and will engage vtec like a regular y8 motor but the other solenoid is not getting anything, and so the d15b will be going from 12valve mode to vtec instead of going from 12v to 16v to vtec. I'm thinking that the switch once is turned on it will engage the first solenoid so the d15b will be running on 16v like a regular motor and then engage vtec once its supposed. anyone gets my problem? and thanks in advance for any help, and btw the car is a 5 speed and an ex transmission will be used, and no we dont really have the time and money to look for the original ecu meant for this particular engine.

 

So if you guys wire the first solenoid to a switch then every time you guys are or go over 3000rpm you guys need to switch it on which will get annoying if you ask me, espically with a ex tranny shorter gearing then most d series tranny

 

^^^yes but the switch will be turn on right before driving and turned off once the car is off, reason why is because i believe the d15b will run rich with the p2p ecu from 0 to 3000rpm since the d15 is meant to run on 12 valves during those rpms and the p2p ecu is meant for a motor which is running on 16v all the time, do you get me?

 

Well Honda design the D15b 3 stage vtec for better fuel economy so your just basically gonna make it run on all valves soo I dont belive its gonna run richer since its goona be working like a regular d series engine all the time

 

thats my point so if the switch is on all the time, it would be like running a regular vtec motor, and I'm guessing this theory would actually work, the p2p ecu and switch for the first solenoid?

 

Yes it will work, or you don't have to get a switch and wire in an rpm activated switch.

 

No just get the correct ECU, it doesn't take time to do it just call HMO and tell them you want a P2J ECU for a manual trans. Wire in the additional sensors and be done.

 

This... Or at least stick with using the Vtec Solenoid and just avoid the 4 valve solenoid all together. This 3 stage vtec design is the predecessor to the vtec design found in the 2001+ Civics which just went from 12 valve mode to vtec 16valve mode instead of having 12 valve mode, 16 valve mode and 16 valve vtec mode. The default mode on these motors with no solenoid activated is 12 valve mode. You want 12 valve mode because that increases low end torque and fuel economy. The reason to have all three modes is that it flattens the torque curve and should improve overall fuel economy (efficiency).

IMO if you've got the rare engine, it'd be a waste to not take advantage of its features.

 

This **** NEVER works properly without the correct ECU-the P2J. I suggest you get one and skip all the hair brained schemes to work around what you don't have.