Is this VTEC disengaging in our R18?

[lineric]

Hey All,

Yes, I know how VTEC works in our R18, and I remember seeing a description saying "VTEC disengaged above 3500rpm OR when engine is on high load". Now during street cruise (usually in 3rd gear @ 35~40km/h with almost no gas) if I step down my gas usually I feel this sudden disconnection of power for less than half a second before the speed picks up. Is this VTEC disengaging from economy to regular cam? This would happen mostly in 3rd or 4th gear when I want to accelerate and press a bit hard on gas. Anyone who also experienced this?

Eric

[Aastan]

Yes, I have experienced this but am unsure of this situation also. Any takers??

[Dickotine]

Well if im not mistaken, our vtec disengages only after 5500rpm's and thats when the engine goes into normal mode. ur Vtec (i think) only engages between 2500 and 5499rpm's for fuel economy. anything over 5500rpm's its completely off. The Vtec cams open up mid-open at 3500rpm's and fully open after 5500, de-activating V-tec. I can be wrong, but this is how i understand it.

[Dickotine]

Its like that pause your waitin for is your "Intellegent" Vtec styled engine to realize that your sending more fuel to the engine and to open up the intake lobes or whatever opens up to allow more air into the engine to open up mid-way to get some acceleration and thats the pause u get.

[mO 64 StAnG 06]

Im not too sure on your situation but vtec disengages roughly around 3000-3500 RPMs for us R18rs.

I take it you have a manual. But from what it sounds like to me it's just your car responding to the sudden increase in the throttle you added. Of course the car isn't going to rocket off right as you are pushing down on the accelerator.

Really, I can't tell too much of a different when we crossover other than sound from the CAI I have installed. So I don't think in your case that thats vtec disengaging.

[av911]

Originally Posted by Dickotine

Well if im not mistaken, our vtec disengages only after 5500rpm's and thats when the engine goes into normal mode. ur Vtec (i think) only engages between 2500 and 5499rpm's for fuel economy. anything over 5500rpm's its completely off. The Vtec cams open up mid-open at 3500rpm's and fully open after 5500, de-activating V-tec. I can be wrong, but this is how i understand it.

It's 1000-3500 RPM.

Civic 1.8L iVTEC chart

[06CivEXJon]

Whats the noise i hear at 2000 RPM?

[mO 64 StAnG 06]

The engine.

[KameraBoy]

probably just dbw lag.

[drnknbndr]

Originally Posted by mO 64 StAnG 06

The engine.

Hahahahahaha.

[lineric]

Technical Overview of Honda's new R18 i-VTEC Implementation

In this article I think what I got out of it is 3500rpm does not serve as a cut off point, but rather

>3500rpm: economy cam off at all time, engine running with normal cam
1000~3500rpm: economy cam and normal cam can switch interchangably depending on the loading condition of the engine.

In my case usually I'm cruising at steady speed(1) with engine rpm relatively low(2) (1.5K ~ 2K range), thus should establish the environment for economy cam to kick in. Then suddenly I press down the gas, and supposedly had increased engine load, resulting the economy cam to disengage. I know this is all hypothetical, which is why I'm asking to see if any civic owners have experienced the same thing.

Yes my civic is a 5speed.. and as all you manual drivers know we're especially sensitive to throttle/rpm reaction when we're driving. And no it's not dbw lag, it's a completely different feel.

I suggest those of you who does not have a clue what (the !@#%) I'm talking about try my method described above before flaming me being nonsense.

The sudden disengagement of power is there for sure, just I'm not sure why yet...

[TcivicT3]

i notice the change around 3.5-4k but i wouldnt consider it a loss of power

[mO 64 StAnG 06]

I mean, I don't fully understand what you are asking in this thread.

Are you wondering why the car feels like it has no power when that low in the RPM range? It's because we have no torque.

Are you wondering if that pause of power is actually the cam change or whathaveyou? Possibly.

But from what I am seeing and from experience in my own car, trying to accelerate without gear change while only within 1.5k-2k RPMs will get you no where. Our car's have no torque and by trying to accelerate in that range is just a waste of gas. All you are doing is loading the engine.

Just drop a gear or two.

But I still think it's a bit of DBW lag and bogging the engine with increased fuel suddenly.

[sf08ggm]

i know exactly what this guy is talking about because i experience all the time and its the first civic ive had that does this and its really wierd...... let me try to explain...... you are driving around slowly just cruising, shift at 3k rpms every gear, the car drives normal no problems..... now start off in first go to 3k rpms still driving slowly as usual, shift to 2nd do the same thing slowly, still fine..... now when youre in 2nd, this time go to 3k rpms again (in 2nd gear still) push in the clutch go to 3rd and then press on the gas kinda hard like u wanna accelerate fast..... the car does a wierd sudden loss of power, like u stepped on the gas but the ecu didnt realize it, it takes just 1 second, then it finally reacts and you start accelerating again..... its like a wierd "bucking" or "hesitation".....almost like the car lags for a mere second before starting to take off..... which seems odd cause none of my other civics have done it.... and ive owned a 92,95,96,99, and 03.......

[mO 64 StAnG 06]

That's probably the switch then. But I have no clue.

[bballstuffer]

I think it's our mind, let me explain.

When you depress the gas paddle, you expect the car to accelerate, but due to the low torque and dbw lag (mainly dbw lag I think) that the civic has, your mind is thinking ahead of the motion of the car. So, you would move your body forward a little to try to compensate the increase in G-force that is expected from the car, but in reality, that car was not able to perform that sort of performance. And this is why you feel that hesitation.

(If you ask a passenger, they will tell you that the car accelerates smoothly. Because the passenger's brain is independent of the car, whereas you, your brain is kind of in-sync with your foot and the gas paddle)

A second or two later, the engine RPM ranges will get higher, then you will feel the power.

Originally Posted by sf08ggm

i know exactly what this guy is talking about because i experience all the time and its the first civic ive had that does this and its really wierd...... let me try to explain...... you are driving around slowly just cruising, shift at 3k rpms every gear, the car drives normal no problems..... now start off in first go to 3k rpms still driving slowly as usual, shift to 2nd do the same thing slowly, still fine..... now when youre in 2nd, this time go to 3k rpms again (in 2nd gear still) push in the clutch go to 3rd and then press on the gas kinda hard like u wanna accelerate fast..... the car does a wierd sudden loss of power, like u stepped on the gas but the ecu didnt realize it, it takes just 1 second, then it finally reacts and you start accelerating again..... its like a wierd "bucking" or "hesitation".....almost like the car lags for a mere second before starting to take off..... which seems odd cause none of my other civics have done it.... and ive owned a 92,95,96,99, and 03.......

[koonce727]

its called having a DBW throttle body

I recommend the nst pulley kit to help out with throttle response

[lineric]

Umm... not really

This sudden "lag", as many of you might call, does NOT happen as soon as one depress the gas paddle. Rather it happens during a constant, steady acceleration; sometimes very shortly after, sometimes longer depending on how hard you hit your gas pedal. I used to own a 125cc scooter that has the same dbw-lag-like behavior (due to ECU control) you described, and it is completely different than what I'm trying to get at here.

The closest thing I can think of is probably try imagine you're accelerating, and you press and release clutch really quickly for a fraction of second. That is more like what I'm experiencing with the lag, and I doubt it's dbw or our brain trying to trick us

Originally Posted by bballstuffer

I think it's our mind, let me explain.

When you depress the gas paddle, you expect the car to accelerate, but due to the low torque and dbw lag (mainly dbw lag I think) that the civic has, your mind is thinking ahead of the motion of the car. So, you would move your body forward a little to try to compensate the increase in G-force that is expected from the car, but in reality, that car was not able to perform that sort of performance. And this is why you feel that hesitation.

(If you ask a passenger, they will tell you that the car accelerates smoothly. Because the passenger's brain is independent of the car, whereas you, your brain is kind of in-sync with your foot and the gas paddle)

A second or two later, the engine RPM ranges will get higher, then you will feel the power.

[milo00]

if its AUTO Its the Shift ... Totally sure!

[mO 64 StAnG 06]

Originally Posted by milo00

if its AUTO Its the Shift ... Totally sure!

But are you sure he has an Auto....?

Stay tuned, as the answer of this question is only a few post's up!