stock 92 civic vx vtec question?
 

i am trying to verify how this works? i notice when i accel past the rpm when vtec engages there is NO increase in power or acceleration. it seems exactly the same before and after. and it doesnt matter what gear. does the civic vx vtec work different than others? it seems to me vtec is engaged all the time except when it goes into lean burn then it disengages and goes to 12 valve mode to get good mpg's. so maybe for the civic vx the vtec rpm switchover is just to limit running in 12v mode and forces it to 16v mode?

O come on! NO ONE here knows how the vx vtec works???

Yes. Under ~2500rpm vtec is NOT engaged, the engine is running using 12 valves. Engaging vtec just engages one additional valve per cylinder for a total of 16 valves.

If you can find a Honda factory service manual online, it contains a in-depth description of vtec-e.




ZO.

It looks like you've already ASKED and people have answered. It hasn't changed.

Find a Honda FSM and read it for yourself.




ZO.

so at idle its 12v? i disagree. when you accelerate from idle and dont let it get into L/B and you rev past 2500 rpms does the motor gain a sudden increase in power? no it doesn't. then this means vtec it always engaged from idle on and only disengages for L/B.
i dont know how test the 02 sensor to confirm this though. how would you do this? just a volt meter?


[/QUOTE] Engaging vtec just engages one additional valve per cylinder for a total of 16 valves.[/QUOTE]

correct.

yep and i think there wrong.

Description from the Honda FSM:
http://i62.tinypic.com/2ew2pas.jpg

The secondary intake CANNOT fully operate until vtec-e engages the secondary intake valve rocker arm...above ~2500 rpm. So at idle, it's a 12 valve engine. Whether or not you FEEL an increase in power. Which, speaking of power, the engine is only capable of 92hp at 5500 rpm. Vtec-e isn't going to put you back in your seat when it engages.





ZO.

If you accelerate from idle what rpm are you shifting at and how "hard" is your acceleration? This isn't a DOHC B18C5, it's a SOHC D15Z1. There is no power!

http://i62.tinypic.com/14aih77.jpg

http://i61.tinypic.com/m7ymuq.jpg


Vtec-e doesn't engage at low rpm, so how you can agree with this statement and not the other doesn't make any sense.




ZO.

http://i61.tinypic.com/m7ymuq.jpg


Actually looking at the graph, lean burn can be kept to 3000 rpm and 3.5 in. hg. Good to know now that I've installed a vac gauge!





ZO.

i know its not going to through you back but you should feel something??? this is my point. the only time you you feel a kick is when coming out of lean burn. as you stated before the 2500 rpm switchover it is just to keep 12v mode out. so below 2500 when your in L/B and you hit the throttle its going to 16v mode(vtec on) even at idle.