With the number of Honda P28 VTEC ECUs becoming scarcer, it is now even more cost effective to convert your non-VTEC p06 ECU to VTEC. Believe it or not, it is not that difficult. With the right components, any OBD1 P06, PR4 or P75 ECU can be converted to be electronically equivalent to a P28.
Note that your non-VTEC ECU will need to be connected first and a VTEC engine ROM chip added as VTEC components alone will not allow the ECU to properly operate a VTEC engine without the correct program.
First things first, there are three different board versions for OBD1 Civic / Integral ECUs. Each version of the board uses unique components to control VTEC operation. The three license plate versions are ’11F0′, ‘1720’ and ‘1980’. Open the ECU cover and in the upper right corner of the ECU plate with white letters you will see an identification code similar to something like ‘2D01980-1902’. This plate is categorized as a ‘1980’ plate version as it is in the middle of the code.
Once you have identified your board version, you will need to obtain the correct VTEC conversion parts for your specific ECU. Be careful when purchasing the VTEC conversion kit as not all are the same. Make sure to select a kit that uses quality components as using sub-torque components will lead to the occasional check engine lights not having a faulty VTEC system or worse, could fry and damage your ECU .
If you don’t have a quality soldering iron and desoldering braid or desoldering gun, now is the time to pick them up. You also don’t have to buy a thousand dollar setup. A simple Radio Shack setup for $ 20-30 will suffice. Be sure to use plenty of solder flux when desoldering and soldering on new VTEC conversion components.