Hi everyone, I have this strange problem, that my vtec doesnt engage, engine is d15b7+d16z6 head, stock p28 ecu, at that moment when it should turn on(4000-5000rpm), i get nothing and only check engine light with 21fault ( I know what is that code), AND my redline is at 6500rpm. oil pressure is good, oil level is MAX, oil jet is removed from the block,no dents in the oil pan, Solenoid is clicking when giving 12V directly, All the wires are wired in correctly, and good. Solenoid itself is good and within service manual specification 15-30 omhs, ECT is working properly.

red all the topics in forum, my speedometer at one moment in its life was showing nonsences but now it fixed itself ant working properly, shows speed correctly, shows that engine speed is going correctly to 6.5k rpm.
my next step is to get an eeprom with everything dissabled (what needed to engage vtec), but before that I would love to hear what else I could check on.

 

You say the wiring is correct, this is the only bit, if everything else checks out like you say, that would be the issue or a bad ECU. If the chassis wasn't a 92-95 Si, the wiring isn't there natively and you may have the two wires to the wrong pins on ECU as well as possibly not have it grounded to G101.

 

Strange thing is, that i had previously d15b7 block, d16z6 head, d13b2(EU) pistons. And everything was working fine, after engine swap, I did nothing to wiring. and it stoped working(same vtec solenoid). But FIXED IT TONIGHT. Did D6(I think D6, what ever that other pin) to A4 on the ecu, and one wire to the vtec solenoid. disconnected from vtec switch that 2 wire connector. and it's magically started working. no cel, pulls all the way. I will keep this thread maybe there will be like me searching whole internet, and not finding the answer.