As I understand it, our VTEC implementation is extremely simple:
a. The VTEC solenoid trips at 5900 rpm, unless the engine temperature is too low, which then overrides it.
b. This opens a passage which allows oil pressure to move a simple rod.
c. The motion of the rod locks up the 'high lift' cams on the camshaft, allowing them to act on an additional set of cam followers, which generates the longer duration and higher lift of the valves, leading to the high rpm performance which we all love to experience.

Because this mechanism is fairly simple, I assume that it rarely breaks down [also, I have never seen any threads related to such failure here at s2ki.com]. The so-called Honda iVTEC is more complicated, and certainly does vary the rpm of engagement, and perhaps some other factors beyond my feeble intelligence to explain. I would like to think that the 'simple minded' VTEC of the S2000 is every bit as effective as the 'intelligent' VTEC, and its only real disadvantage is the slightly lumpy feeling as the transition at 5900 rpm is crossed. I am assuming that by periodically exercising my S2000's VTEC solenoid, I am giving the VTEC functionality a good health check, preventing a sticking solenoid occurrence, and enjoying myself.

By comparison, some other non-Honda variable valve timing implementations are more elaborate. I do know that the BMW VANOS system does use a progressive motion, depending on rpm, to gradually vary both the valve timing and lift. It would be more seamless than our VTEC, and thus more appropriate to a luxury car like the Beemer, but I have heard that the mechanism often wears out and needs replacement at 60,000+ miles. VW uses variable valve timing on the Passat V6 [my 'other' car], and I can assure you that it is absolutely seamless and must also be gradual in nature. Still, I worry that someday the controlling equipment may go bad and cost me a bundle of $$.

I do hope that someone here with a slightly higher Gearhead IQ than I can either confirm or correct my comments. Thanks.

 

our VTEC does change engagement based on MAP. it is not a hardcoded rpm value.

 

i-VTEC adds a smarter version of the software to prevent operation at cruising speeds for better fuel mileage. It also has a mechanism that hydraulically actuates a cam timing device on the timing belt side of the cam.

As far as VTEC reliability goes the ony failures I have ever come across is sticking plungers and inop VTEC due to lack of regular oil changes and low oil levels.

 

Two questions..... excuse me if there dumb ones

1 isnt the v-tec stop working with low oil ???

2 what is MAP ???

 

1. That has been reported but makes no sense. There is no oil level sensor and low oil pressure (which would affect operation) should not happen until pump starvation occurs. I think there may be some perception of failures that may not be factual.

2. Manifold absolute pressure. Honda does not use an airflow sensor but rather measures the pressure (vacuum) in the intake.

 

ahhhhhh.....thanks for the info ...... I see lingo
with this stuff all the time but not always sure
what there referring to

 

HELP !!!!!!
Check engine light is on and my VTEC doesnot enter to work after 5900 RPM
Need help to know what to repair