I just got my PMS, and I want to wire the aux port to control my vtec engagement. I know that I need a four wire, 30A relay to do this, and I know that I need to wire this into the vtec solenoid wire from the ecu. Obviously I cannot keep the ecu side of this wire connected because it could fry the ecu when the aux port engages. I need to know what I can do to trick the ecu into thinking that it is still connected to the vtec solenoid so that it does not throw a CEL. I am installing this on a 2000 lude. Any insight would be appreciated.

 

I think a reistor will do the job. Do the 2000 prelude have a VTM (VTec Pressure) sensor? I did the trick on my selfmade VTec-Controller this way: connect the VTec-Solenoid line and the VTec-Pressure line together (the lines are not connected to the engine bay, you have to modify the ECU-side of the wires) and tie it with a 1k Resistor to ground. So when VTec is not engaged the ECU see a low voltage on the line and knows everything is ok, when VTec is engaged, the VTec solenoid line has +12 Volt and throug the junction to the VTec Pressure line the "answer" is +12, too. And again, the ECU knows everything is ok.
Ok, on my way the VTec solenoid was still connected, and so the total resistance is different. But in your case, i think, it will work with a resistance like the VTec solenid has.

I would even not use a relay, i prefer a "power transistor" solution. Cause the relay will delay the engagement of the VTec solenoid. (first the relay must be fired (will take a little time, some ms) and then the VTec solenoid (will even take some ms)).

If you don't like this complicated way, stay with the relay and engage the VTec some rpm's befor your desired point. (might me fix the delays)

If all above sound to complicated, i've to excuse me, cause i'm an electronic technican. And even for my bad english, too.

Christian


[Modified by doc, 6:55 PM 7/20/2002]

 

I'm thinking about running the ecu side of the solenoid wire to ground with a diode and a resistor in between. The total resistance needs to be between 14-30 ohms, or the ecu will throw MIL 22. Problem is I am electronics impaired, and I don't know exactly what kind of diode I would need.

I'm going to stick with the relay method. My setup is going to be dyno tuned anyway, so rpm setting will be arbitrary and relative to what will make the best power.