frankn_d16_ek

alright fellas let me get straight to the point, my car engages vtec at around 6500 instead of it engaging at 5500, i have checked the oil pressure, its fine. ive checked the code its throwing and its for the oxygen sensor bank 1, i was told that shouldn't be the problem . so what could make it engage like that?? the ecu is fine nothing burn't inside it that i can see, and the solenoid is good it engages fine. so im stumped but any info is greatly appreciated. thanks

mattc28

How do you know for sure that it engages exactly at 6500??

frankn_d16_ek

well give or take a hundred, but like i said it does engage around 6500 i can actually hear when it engages unlike most d-series where you can barely hear it if at all. but i thought it was suppose to engage at 5500?? or am i wrong. either way idk and would like to figure this out before i swap the motor. i plan on putting it in a ef hatch sooner or later and would like to have it figured out before hand. let me know fellas, thanks again.

cpvdh

so the cel is on?
if so it may be in limp mode and not engaging vtec at all

pslsnakes

Check your oil. Since my rear main seal is bad, mine leaks a good amount of oil. When I'm low, I notice that vtec doesn't engage at 6k rpm, like it does when I'm good on oil.

And vtec shouldn't work at all if there's a CEL on. Atleast that's what I've read. Replace your o2 sensor and see what happens.

frankn_d16_ek

yea i plan on doing that this weekend, but my buddy has a 96 ex and it was throwing a code for the oxygen sensor as well but it still engaged right at 5500, so to be totally honest with everybody im stuck in a hole right now with which way to go. but ill try replacing the o2 sensor and see if that takes care of it. thanks again for the help fellas.

frankn_d16_ek

ok fellas heres something new, i went out and checked my code and its not a 02 sensor as i was told, its throwing p0420 for a misfire, vaccum leak condition. now my question is will vtec not engage right if theres some type of leak or misfire in one of the cylinders?? im still trying to figure this out!! im really knowledgeable on non vtec motors so this is kinda new to me. sorry for the run around guys, thanks again.

A-series

Where it's supposed to engage depends on the engine, mine's a D-series and it engages at 4800rpm (WOT), like it's supposed to.

VTEC won't engage (switch cam profile) for a variety of reasons, things like coolant temp., oil pressure, and vehicle speed have to be within the parameters. Where it engages, (either the WOT rpm or higher) goes off intake manifold pressure, at least on the older cars - that's how it judges engine load, similar to how some automatics determine whether to hold a gear or upshift/downshift.
It's possible that an issue with the MAP or it's connections, w/ the throttle cable (not allowing WOT), or maybe something with the intake manifold itself, could cause later engagement - that is if you're floored and it engages later than it should at WOT.