Civic EG

hey guys i gotta small kink my vtec is not engaging at 5200 like its supposed its flickering on and off from 4700 till i reach 5200 which is not very efficient. anywho i was thinking my vss but my speedo and tach are working fine anyhting else that would cause a premature vtec flicker/engagement?

any help would be great

thanks

Mac

it activates from oil pressure, so maybe try cleaning out the solenoid. also maybe a bad oil pressure sensor?

How do you know whether is on or not?

Besides RPM there are several other parameters that determine whether it's engaged or not, ie throttle angle and load. If you are having this "problem" at part throttle, that could explain it.

I know vtec-e is activated by throttle & load as well as RPM, but I thought that regular vtec found on the obd1 cars was not going to change activation points based on those things. I thought it was always the same RPM when it activated

At least my d16z6 seems this way, but my D16y5 is exactly as you described. school me

i have a light hooked up to my solenoid and i can hear it changing on and off in rapid sucsession. previously it has always come on at 5200 rpm. but when i get it into my shop il clean out the solenoid and what have you.

To be honest teal_dx I haven't observed it myself. But from what I've heard there are multiple parameters. I make the mistake sometimes of assuming that what I see in the AEM EMS software is a replication of the stock ECU's functionality.

I am 100% certain that there's hysterisis. In other words, there's a VTEC on RPM, and a VTEC off RPM. If your VTEC On RPM is 5200, then your VTEC Off RPM is probably 4900. Otherwise if you held your RPM's right at the VTEC crossover RPM, the small fluctuations in engine speed would cause the solenoid to flick on and off rapidly kind of like what the OP described.

To confirm what I'm saying you'd need an accurate diagnostic tach or gauge as the factory tach is off by a few hundred RPM and moves much too slowly to draw any conclusions.

Clean the solenoid

or maybe a bad connection / short in the wiring for the vtec solenoid or oil pressure sensor