Wiring 3 stage VTec in an EG and a P28 ECU.

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thumper1989

New Member
I think I came up with a way to have true 3 stage VTec here in America, with a USDM ECU. Have the solenoid activating the "wild cam" controlled by the ECU. That's easy.
Then for the "econo" solenoid, have it controlled by one of these. MSD Ignition RPM Activated Switch Any RPM controller would work, I just saw this one though.
It sounds like it sends power when an RPM level is reached, so a solenoid would need to be wired in, possibly.

Why haven't I seen anyone do this? Is there a flaw I'm not seeing, or am I not searching in the right place?

I would likely need to get a new fuel map (the P08?) on the ECU, but once I do, it should work, right? Maybe add a wide band O2 sensor to allow lean mode to work correctly?
 
why would you want to do it?

do you think honda would do this if it was the best for these engines?
 
I would want to do this to have 3 stage VTec. There aren't ECUs for OBD 1 cars that will control it, so this is more a last resort type affair.
Honda wouldn't do this, that's for sure. But I haven't seen any other ways.
 
i still don't understand why you would want to do this?
 
Honda actually does have a 3-stage Vtec system but is was only offered in Asia. Basically at low RPM the engine works in 12 valve mode. Only 1 intake valve opens instead of two, this causes a swirl effect inside the combustion chamber that gives the engine better fuel efficiency. Above 2500 rpm the engine goes into Stage 2, which is like most Vtec engines at mid rpm. Both intake valves open. And then at High rpm and WOT. The third Vtec stage is initiated which is the high lift lobe. It's pretty neat, The engines with this system have some of the best fuel efficiency/ power ratios seen.
i still don't understand why you would want to do this?
 
Last edited:
https://hondaswap.com/ecus-electronics-tuning/d15b-vtec-3-stage-wiring-58066/

I think I came up with a way to have true 3 stage VTec here in America, with a USDM ECU. Have the solenoid activating the "wild cam" controlled by the ECU. That's easy.
Then for the "econo" solenoid, have it controlled by one of these. MSD Ignition RPM Activated Switch Any RPM controller would work, I just saw this one though.
It sounds like it sends power when an RPM level is reached, so a solenoid would need to be wired in, possibly.

Why haven't I seen anyone do this? Is there a flaw I'm not seeing, or am I not searching in the right place?

I would likely need to get a new fuel map (the P08?) on the ECU, but once I do, it should work, right? Maybe add a wide band O2 sensor to allow lean mode to work correctly?
 
I know that Honda has 3 stage VTec, that's what this D15B has. It has the two solenoids. The only thing is the engine is a Jap import. There isn't an American OBD1 ECU to control both solenoids on the head. Switching to OBD2 would allow use of a different ECU, but I want to keep OBD1.
 
Switching to OBD2 would allow use of a different ECU, but I want to keep OBD1.

Why though? I assume you're swapping this motor for the fuel economy, not because you want to build it and tune it? If that's the case then why not just swap it over to OBD2 and run the appropriate ECU? That seems like the best option to me. If you don't plan on tuning it for performance, then there's really no reason not to swap to OBD2...
 
Why though? I assume you're swapping this motor for the fuel economy, not because you want to build it and tune it? If that's the case then why not just swap it over to OBD2 and run the appropriate ECU? That seems like the best option to me. If you don't plan on tuning it for performance, then there's really no reason not to swap to OBD2...

Indeed, it would be for the fuel economy. Plus having the second stage, it should make plenty of power for just putting around and regular daily driving. Most likely I'll end up selling the car after swapping it, since the current engine burns a quart of oil every 80 miles. When I get on the throttle, it smokes right around 4500 rpm.

Anyway, how hard would it be to swap to OBD2? I assume I'll need to add a second 02 sensor and obviously buy an OBD2 ecu.
 
If motor replacement is all your after, use the OBD1 D15b VTEC. It is a direct swap into your car ( depending on trans type, auto to auto man to man) and three new wires to hook the vtec into either a usdm p28 or go wild and have it chipped with p08 maps or use the "p08" they engine company can supply you with. I use "" because I thought I was gonna get a p08 but got a flashed p91. the third stage of the vtec in the obd 2 motor is sort of pointlesss, how often do you really plan on being on part throttle and also have a need to throw the hammers down? if you had an obd2 car I wouldnt say this but lets amortize any potential fuel savings with the third stage versus the cost of the wiring needed to run it and you would need hillary clinton and a gas holiday for the summer and part of the fall with an economic stimulus rebate check to break even. Its an attractive motor in a very Spinal Tap kinda way " but this one goes to 11!" or if you want a sig on the boards that says " I got three stages of vtec, want one?"
 
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