Ok so I have a 1992 Honda civic cx with a 1994 gsr. I have the engine harness for the gsr and everything is plugged in correctly. My only code left after fixing a couple of them is code 21 vtec. I've tried a lot
Of things. For one I tried running vtec straight to the ecu. That didn't fix it. The solenoid works properly. I supplied power to it and it clicks along with it's ohms out within spec. Nothing has fixed it this far. What should I try next

 

Take the selonoid off and clean the screen.

 

New gasket done and done.

 

Find the wire(s) that plugs into the selonoid and do a continuity(spelling?) Test. If that dnt work, you know you have a break in your wires. Did vtec stop working oit of the blue?

 

No it's never worked. Like I said I ran the wires directly to the ecu and nothing. Continuity is good

 

You might have a messed up harness/ecu. What ecu you have? You ran your own wires? Might be tedious, but run your own wiring. If it works then, then you know your harness has been tampered with, or just a break. Not a rare issue..If you are certain harness is good, id suggest another ecu.

 

Does code 21 pop up as soon as your start the car or after passing the VTEC crossover point?

 

Run the engine, under the hood get a jumper wire and jump it from the battery to the vtec solenoid and the engine should bog or change in sound, that means your mechanical side of things is okay. If that works, check your wiring to the ecu and you also need to have the pressure switch wired in to the ecu as well and grounded. If you think you may have a pressure switch issue, you can run both off one wire to the vtec solenoid and split them at the ecu and run both pins to the one wire. If that works then you have a pressure switch or wiring/grounding issue.

 

If using the above method, make sure engine speed is above 3,000 rpm. I don't believe the engine will make enough oil pressure below 3k to allow VTEC to engage.

 

Usually works on a cold engine, but if its an older engine you may have to raise it up like posted.

 

The above method BYPASSES all the ecu checks and puts 12v from the battery straight to the solenoid. Itll force vtec to engage as long as the solenoid is functioning correctly

 

replace the oring could be the filter is clogged. oem# 15825-p08-005. also how clean is your oil and is it full? dirty and/or low oil might not be building enough pressure. if those are good might wanna check your oil pressure.