VTECH rpm

[DRZZZ]

Sorry to ask this question....(I already did a search)

What rpm does VTECH kick in? I'm asking because my car seems to stumble/accelerate around 6000 rpm. To be exact, it's 5500 in first gear, and 6500 in 2nd gear. Is this the VTECH mechanism?

Thanks for your help,

Dave

 

[brahtw8]

Perhaps you found nothing because you were searching about cordless phones?

It is VTEC, not VTECH.

http://www.nsxprime.com/FAQ/Technical/VTEC.htm

 

[X 02]

With all those wannabes and imitations out there or who just can't come up a better name for themselfs, it's really confusing sometimes. How you like my Adibas or my GUGGI?

 

[rrwildman]

One of the coffee table books states that the VVIS transition occurs @ approx. 4800 RPM, and that the VTEC transition occurs @ approx. 5800 RPM.

That book was published with the initial release of the car (3.0 engine), and I don't know if it changed with the later displacement increase (or which engine you have, for that matter).

Richard
'93 Blk/Blk

 

[MLmotorsport]

Same thing happens to me at those RPM's!

I was just getting ready to post the same question. I'm not too mechanically smart - so, short of taking it to the dealer I was going to ask if this is normal. It's not that noticeable. Most people probably wouldnt notice it, but at those rpm's theres a slight tick and split second of hesitation (for lack of a better term).
Any ideas?

 

[rrwildman]

I don't know what you guys are experiencing, but will throw out a couple of general comments for consideration.

Under normal circumstances, both the VVIS and VTEC transitions are noticeable to an alert driver, however the VTEC transition is considerably more noticeable.

I believe those transition point RPMs SHOULD be the same regardless of gear.

In first gear, RPMs climb rapidly enough that it can be more difficult to tell exactly what RPM they're occurring at than in, for example, second gear.

Under normal circumstances, although the transitions are noticeable, I don't think you should perceive a "stumble" or "miss" in the process; just a quick change in power output and intake/exhaust note.

If something were wrong in the actuation mechanisms which resulted in the transitions either occurring at the wrong RPM, or taking an abnormally long time to occur when they do, I suspect that either would alter the perception of the transition noticeably (negatively).

First, in second gear, I'd try to determine whether or not the VTEC transition IS occurring at the CORRECT RPM. If it is, and that's where the "stumble" occurs, then there may be a problem with the acutation mechanism affecting the timing of the transition, etc. If it is, but you notice a "stumble" at a different RPM, then the stumble might be less likely related to VTEC. If it's not occurring at the correct RPM, that in itself is a problem. In that case, perhaps it IS occurring at an incorrect RPM, and that might be the cause of the stumble you're noticing at another, incorrect RPM level.

These comments are along the lines that, when trying to figure out what something is doing WRONG, a vital component of that process is often figuring out what it is/isn't doing RIGHT.

Just some thoughts. In any case, if you're accelerating in a gear and noticing anything other than a positive increase in power output (a stumble or miss), it would probably be in order to have it evaluated by an experienced NSX tech, as it doesn't sound "normal" to me for an NSX.

Richard
'93 Blk/Blk

 

[DanO]

There are three things going on:

VTEC
VVIS
FUEL PUMP VOLTAGE CHANGE

VTEC
From page 5-7 Service Manual
“Valve Timing Change Conditions”
“Engine RPM: 5,800 – 6,000 rpm”
“Vehicle Speed: 3 MPH or faster”
“Water Temperature 140 degrees F”

VVIS
From page 11-119 Service Manual
Change at 4,800 RPM

Fuel Pump Voltage
I can’t find a direct reference to this switch but I think it’s at 6,500 RPM.

The “click” sound that comes from behind the driver’s seat is the fuel pump relay switching the voltage (bypassing the resistor) to the fuel pump. I think this occurs at 6,500 RPM. There might be a slight change in intake or exhaust tone at 4,800 RPM when VVIS changes but I bet it’s hard to hear. In my experience with the NSX, the VTEC changeover is hardly noticeable and should not result in any significant acceleration change.

It might be a fuel pump relay problem.

.02

DanO

 

[MLmotorsport]

Ahhhhh - I think that's it!

Thanks DanO! I drove it tonight. I think what i described as a hesitation was made up in my mind - there really is no hesitation - but that click really threw me! anyway, the car is mint and has been babied, overmaintained really, so I'm not worried anymore.

sidenote: what do I mean by "overmaintained"? The car just had the TB & WP done a few months before I bought it (a month ago today). Upon inspection at the Acura dealer, they informed me that the TB & WP were done just a couple years ago at their dealership... and not by this owner! He got screwed by another Acura dealer in the Atlanta area is what it comes down to (he had the reciepts). They said he needed to have all that stuff done on his last service. he was replacaing the clutch etc etc so maybe it wasnt as big of an expense had he just been doing the TB/WP but still - not needed! His loss, my gain
Off topic yet again. I should probably post this on another forum but I'll throw it in while I'm at it. Anyone have any idea what a port/polish job would add to the HP? he had that done too.
Thanks to all!
Love this place!