radialsymmetry

lets say im in third gear and i accellerate revin the rpms to 5k then let up on the gas and allow the engine to slow, rpms droppin, still in third gear i apply pressure on the gas and it noticably nudges or slightly jerks forward. i bought my 06 a month ago and have since learned the clutch (dif than my 96 jetta). i love it, but the slight jerk just feels like it doesn't belong... does anyone know what is causing this???

ThirdLane

Most likely the aggressive throttle tip-in from the DBW

hunterk1

+1 It's hard to drive the car smoothly. The DBW is very nonlinear near the closed position.

nj2pa2nc

I can drive it smoothly. It takes awhile to get used to it, especially if you drive other vehicles that have MT (we have a 05 Hyundai elantra gt 5MT and a 07 Mitsubishi Raider truck with 6MT.

miken5678

same issue with mine even the slightest touch to the pedal will cause it to jerk.. only time is doesnt is while it is in cruise

gftgrill

when you take your foot off of the gas while it's still in gear, the computer shuts off the fuel injectors and closes the throttle body.

when you step back on the gas, the throttle body opens and the fuel injectors start providing fuel again.

hunterk1

I can drive it smoothly in terms of clutch action/engagement, no problem - and I agree it did take awhile to get used to it. But it's this I'm talking about:...I haven't gotten used to that yet.

78transam

"when you take your foot off of the gas while it's still in gear, the computer shuts off the fuel injectors and closes the throttle body"

If the computer did this, the engine would die. The fuel injectors do not shut off.

zguy95135

The injectors do shut off, as long as the car is still in gear. The engine is still attached to the transmission and wheels so they turn the engine.

LukeaTron

Way to use your first post to look stupid. The injectors do indeed shut off under certain conditions. The RPMs need to be above certain threshold (I don't know what it is) and the wheels must be turning the engine with enough force to keep the engine turning. For example, coasting down a hill.

If you're going to try to espouse your "knowledge" as though it were the unquestionable bible truth, it helps if you know what you're talking about.

CGTSX07

the jerk u are referring to is normal. to minimize it, you want to very gently step on the gas or don't take your foot off the gas at all. it takes some getting use to..

zguy95135

I think 1500rpm is the threshold, I could be wrong though.

vwong

Yes, it maybe normal in our TSX's (1st gen), but it's certainly not normal in other makes. My Audi doesn't have this "jerking". I think Acura corrected this in the 2nd gen TSX because I didn't feel that during my test drive couple months ago.

CGTSX07

yes, it is one of the only things i dislike about this car.

hunterk1

+1 I don't know what else has DBW but that's a "feature" of the Acura system they need to work out.

If it's gone in the 2nd gen, so much the better; it's too bad they don't release an update to our ECU program that would smooth it out for us.

LukeaTron

I wish I could just mod the ECU to map pedal pressure linearly to throttle plate movement. The biggest problem I have is that the first 10% of pedal travel does nothing at all then the next 1% goes from nothing to 10%. The rest of the pedal travel seems to be fine. I read somewhere that this was to make acceleration in slow traffic smoother but it seems to have 500% the opposite effect, making it very difficult indeed to go from no throttle to any throttle at all without causing that obnoxious lurching.

miken5678

actually with the automatic versions the injectors are shut off below a set rpm for emissions purposes usually below 1500 rpms this was even done in the accords and preludes. with the standard I am not sure.

CGTSX07

i wonder...does the reflash help this at all?

LukeaTron

This is with the car moving right? I don't understand how this would not make the ride extremely rough though.

At any rate, my original point still stands. The injectors do indeed shut off under certain conditions.

feuss2

iTrader: (1)

my 04 6mt did this before and after hondata

there are piggyback devices that will change the DBW curve. information about them is in this forum.

a true remapping would take some work, but would not be impossible. i think there are 2 pots sensing the position of the gas pedal. you could measure the resistance at different positions and figure out where the non-liniarities are, then run a logic-level supply voltage across the pots, sample the signal with an a>d converter and have a pic or microcontroller drive a digital pot that interfaces with the ECU. the problem is, if this fails, you really affect drivability.

perhaps a throttle body with a cable and a kpro is best?

hunterk1

The pots are surely linear; it's the mapping between resistance and throttle position, I suspect, that needs adjustment.

That said, I have to laugh because in the end I totally agree, a cable would do the job just fine... I'm not sure what advantage DBW does in our situation, but with the "econo" i-VTEC it keeps the throttle body fairly open during easy cruising to reduce pumping losses due to pulling a vacuum. It apparently limits cylinder filling & power by delaying intake valve closure to beyond TDC (and presumably limiting fuel as well).

feuss2

iTrader: (1)

the DBW is a part of the VSA system, which I could care less about. there is a fairly popular module to disable it at every startup. cruise control would not work without it.

jlight

Its the drive by wire system,it has more off a on/off feeling than a conventional linkage,you will get used to it but in the meantime you will devellop better neck muscles!

LukeaTron

I also recall reading that the ECU alters the response curve dynamically in response to the conditions. This totally tosses the idea that you could flatten the curve by adjusting the input. The only solution that would work would have to be an alteration to the software.

78transam

The first sentence is correct the second is not. This mode of operation is has been called deceleration fuel cutoff (DFCO). The engine momentarily dies. It restarts when rpm's drop below a specified threshold or the accelerator is pressed. A slight shudder may be the result.