Speed Limiters

[GRK35L]

Hi ,

Was wondering what actually happens when car hits 180km, does the needle stop and car slow down or does the needle keep goin and car stays at speed ?

[PM-R33]

ECU detects speed limit reached, cuts fuel, car slows down below limiter, fuel re-engages, car speeds up again and repeat.

Therefore the needle will just bounce back and forth off 180km/h.

[blk94r33]

ECU detects speed limit reached, cuts fuel, car slows down below limiter, fuel re-engages, car speeds up again and repeat.

Therefore the needle will just bounce back and forth off 180km/h.

I thought on most models the ECU backed of the timing to the point where the car simply can't accelerate anymore? Wouldn't on/off fuel risk damage?

[PM-R33]

Pretty sure it is fuel cut. Most cars use a fuel cut on speed limit and on rev limiter. It doesn't damage the engine since there is no fuel to burn, therefore no combustion.

Ignition cut is what the BeeR Revlimiter and antilag uses.

[grae35]

I can tell you from experience at track days that it is a very smooth process in practise. The car just stops accelerating and speedo needle climbs no further ( though on my car needle is off end of scale- guessing about 190kph position - speedo error!).

It is different in lower gears though and on the skid pan in 2nd gear it will bounce off the fuel cut rhythmically if you let it.

[scotty nm35]

The electronic throttle closes as if you backed off to hold that speed. Very accurate too, every pass I did at Calder was 171kph by their measurement.

The maximum throttle opening I have seen with the Stagea is 86%, at launch it bogs down because the throttle is limited to 36%.

[V35_Paul]

Yeah it just maintains it's speed at around 180kmh. As if your cruise control is set to 180kmh.

On my GPS it says my fastest speed i have ever done in the car is 186kmh.

[blk94r33]

Pretty sure it is fuel cut. Most cars use a fuel cut on speed limit and on rev limiter. It doesn't damage the engine since there is no fuel to burn, therefore no combustion.

Ignition cut is what the BeeR Revlimiter and antilag uses.

Wouldn't it be a noticeable "bounce" off the limiter if it's a fuel cut? One GTST i've been in (private property), the limiter just stopped the car accelerating quite smoothly, rather than the usual "derp, a, derp, a, derp, a"

How does it keep the limiter "smooth"?

[PM-R33]

Progressive fuel cut maybe? Not 100% on that one. I have hit the stock limiter in the R33 back in the day and yeah it is very smooth.

In the Vipec you can choose what type of cut you want. You can also set up a 2 way setup for a soft cut and a hard cut so my actual limiter in the car is very smooth now, similar to what the speed limiter was.

[blk94r33]

Progressive fuel cut maybe? Not 100% on that one. I have hit the stock limiter in the R33 back in the day and yeah it is very smooth.

In the Vipec you can choose what type of cut you want. You can also set up a 2 way setup for a soft cut and a hard cut so my actual limiter in the car is very smooth now, similar to what the speed limiter was.

That's interesting. Might need to do a bit more research. That's what I meant, the speed limiter is different to the rev limiter, where the engine reaches say 7000rpm, then just cuts out and effectively starts again. While the speed limiter is more like lifting your foot off the throttle, yet it's cable operated.

You'd think a fuel cut to sound/act like the rev limiter (lol, it is a fuel cut), yet the speed limiter is more of a wall rather than an on/off/on/off. The car doesn't have any means of restricting air intake, so it's either fuel or ignition adjustment to slow things down? But removing fuel partially would make it run lean?

[scathing]

EDIT: Misread post.

Edited May 22, 2011 by scathing

[scotty nm35]

While the speed limiter is more like lifting your foot off the throttle, yet it's cable operated.

The car doesn't have any means of restricting air intake.

Electronic throttle as in "drive by wire".

[T4NK]

So the question everyone is wanting to ask

Is there a way to flash the current ECU to remove limiter or do you have to install a new ECU system to get around this?

[Bourbon Boy]

So annoying this feature. Japs make such fast cars then limit it... My speedometre stops at 180km/ph.

On one track day at Eastern Creek, was over taken by 2 cars down the main straight cause I was just bouncing on 180.

I didnt feel any cut off jerks or the feeling of slowing down, the car just wasnt going any faster.

So yeah, back to what T4NK was saying. How do we fix this?

And when the limiter is cleared, how would we replace the speedometre on the dash so it reads above 180 (like from an US market G35) and also reconfigure the dials so the needle is acurate with the speed of the car.

Edited May 23, 2011 by Bourbon Boy

[blk94r33]

Electronic throttle as in "drive by wire".

Whoops. I was talking R33's, OP's car has drive-by-wire.

[zei20l]

how to fix?

new ecu or ecu reflash. i dont think you want to be screwing around with the CAN signals

[PM-R33]

Whoops. I was talking R33's, OP's car has drive-by-wire.

Hahaha yeah when I originally made my first post I forgot it was in the V Series section. So theirs operates with the electronic throttle aswell.

[T4NK]

Well i have the dash replacement down pact http://www.nengun.com/nismo/combo-meter-skyline-cpv35 prity much just recal the speedo once its installed i think.

[vee35]

... prity much just recal the speedo once its installed i think.

Is it possible to recallibrate the std spedo? they are usually wrong out of the factory, and mine is worse due to the low profile tyres.

[T4NK]

Is it possible to recallibrate the std spedo? they are usually wrong out of the factory, and mine is worse due to the low profile tyres.

Yeh you can deff recal it. there are shops in syd that can do it.