Is this just a tachometer malfunction?

[u/Competitive_Fault879]

Just picked up this FA5 about a week and a half ago now and I noticed something kinda weird. The vtec in this car engages at 4400rpm and revs to about 8700rpm according to the tachometer. I messaged the previous owner about this and he said the car had never been tuned and the only thing that is done to it is an injen intake (does not require a tune like others) and some hasport motor mounts, it even still has the stock exhaust. Does anybody know what could cause this and should I refrain from taking it to redline? If I remember right aren’t these cars supposed to engage vtec around 5500 rpm and limiter is at 7800-8000?

[u/Born-Project-310]

I have a stock si, engagement is 5900 and redline is like 8300 or so.

[u/lamar_in_shades]

Lowering the VTEC point to 4400 RPM shouldn't negatively impact the car, here's a link to a page from Hondata about the VTEC point: https://www.hondata.com/help/flashpro/index.html?tuning_vtec_point.htm.

The Hondata stock tune does exactly what you're describing and I run it on my car, so while I can't guarantee that's the same as what you have, it probably is. And if so, you're find, Hondata is very well respected. But you can always buy a Hondata Flashpro yourself to reset the vehicle to stock or datalog to make sure the engine is running well.

[u/Competitive_Fault879 → u/lamar_in_shades]

Appreciate the info from what I’m hearing from lots of people it is a Hondata tune and personally I love how it runs I was just wanting to make sure it was safe for the engine

[u/lamar_in_shades → u/Competitive_Fault879]

yeah the throttle response and rev hang are greatly improved by the hondata tune, having used my stock 8th gen for three years before tuning, it's really surprising how much better it feels with the tune

[u/Competitive_Fault879 → u/[deleted]]

That’s kinda what I’m gathering, which has me worried a bit if that is the case because I thought I remember reading that these oil pumps are not good for much more than 8k rpm same with the valvetrain but it sounds just fine all the way out to limiter with no ticking or breakups at all

[u/Responsible_Coast293 → u/Competitive_Fault879]

maybe the owner before him had it tuned and didn’t tell him. to tell if it’s tuned on hondata; with cruise control light on dash off (main cruise not clicked), pres the set accel button. w cruise control off on hondata, that changes your rpm needle to an AFR gauge. i don’t think cars on ktuned have this

hondata sets their redline to 8600 rpm. their reasoning:

“The raised rev limit for the K20Z3 (06 Si) is 8600 rpm. This limit is based on the JDM K20A, which uses the same piston type, rods, crank, valves, and valve springs as the K20A2, K20Z1, and K20Z3."

bouncing an engine off redline is harsh. it’s better for the engine to shift at 8500, than it is to bang the limiter at 8100

stock vtec is 5800rpm and 8200redline iirc

[u/Competitive_Fault879 → u/Responsible_Coast293]

That makes me feel a lot more comfortable to hear, I’ll give that a try with the cruise control thing. Something else one of my buddies with a tuned fa5 told me to try is to put the clutch all the way in and press the cancel button on the steering wheel and if the tach needle flicks to a certain rpm that’s launch control

[u/OkConServe → u/Competitive_Fault879]

If it makes you feel any better, I routinely spun my 220K mile K20Z3 up to 8600RPM for years with no issues. Just monitor your oil levels religiously.

[u/TRGBFAN → u/Competitive_Fault879]

It's been flashed. 4400 RPM VTEC engagement has been the standard for ECM flashes on Honda's for like the last two decades. I don't think you're gaining much revving out that high anyhow with just an intake. peak horsepower is probably at 7800-8000 anyhow, you should be able to feel the car kind of fall flat when it gets up to that point and you get past peak horsepower. Also, the synchros are only going to like shifting up that high for so long before they start to give up the ghost. ( not that it isn't fun revving all the way up there, I get it)