Hi folks,
Per my last post, I am tring to get a US p28 Hondata ECU to work with an oil-pressure-switchless JDM B18c5 motor.

I am trying to do this without installing a V-AFC or US Vtec Solenoid assembly.

I am appreciative of all the input, yet the answer is not so clear just yet. We decided to play around with my buddies 1997 US-spec GSR (p72) in order to learn how this system works - this is what we found:

With the ignition on (or engine runnning), the ECU is sending a +12v signal to the oil pressure switch. This switch is closed (has continuity) at any rpm as long as the vtec solenoid is not activated. The connector for the oil pressure switch has two wires going to it - the blu/blk +12 v signal from the ECU and ground.

The oil pressure switch opens (breaks continuity) after VTEC engages (when the solenoid is triggered by the ECU). I believe this is because the pressure switch is measuring oil pressure after the vtec solenoid. We confirmed this by varying the VTEC engagement point. The oil pressure switch always opens shortly after the VTEC spool solenoid is activated.

My interpretation: The ECU is sending a positive +12v signal to ground (through the vtec oil pressure switch) until VTEC engages. At that point, the oil pressure sender sees oil pressure and the switch "opens", breaking the circuit.

Based on this, it seems like you need to wire a relay that breaks the circuit for the oil pressure switch whenever VTEC is activated.

The only problem is that the Helm's manual states that you should see +12 at high rpm and 0 volts at low rpm.

Please let me know your thoughts
-Phillip

 

any thoughts about this??

 

seems like no one is using a p28 on a JDM/euro ITR motor out there...

 

We are but like I said to you on PM it was just easier to do away with the vtec solenoid on the JDM motor and swap it for a USDM solenoid. Have you guys priced out how much a vtec solenoid is used or new.

 

finding a second hand solen. assy would be great, but who has one for sale?

 

Brand new is the only thing I can find. Its thru a friend that gives Honda members discounts. He said he can sell you a new one for $125.00. 5 people buying @ the same will make it $100. Let me know if you are interested.

 

Would a GSR VTEC solenoid work??? There should be many of them around.

AW