Bucking in 1st gear stop and go letting off throttle

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kawzx7
Posts: 31
Joined: Thu Jan 07, 2016 6:36 pm

Bucking in 1st gear stop and go letting off throttle

Post by kawzx7 »

Is there any particular setting available to help alleviate some of this?

Thanks,
Chris
KTuner
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Joined: Mon Jul 22, 2013 8:13 pm

Re: Bucking in 1st gear stop and go letting off throttle

Post by KTuner »

If it's fuel cut related see the fuel cut settings. If it's poorly tuned there, lean or misfiring, tune it.
Audiophyle
Posts: 76
Joined: Sun Aug 18, 2013 8:16 pm

Re: Bucking in 1st gear stop and go letting off throttle

Post by Audiophyle »

Not to resurrect an old thread, but I am having "bucking" issues as well. I have a near stock Element (k24a4) with I&E bolt-ons and both the reflash and base tunes exhibit the same bucking issue. When I am trying to just roll forward from a complete stop the engine lurches heavily as though it is about to stall, and unless I give it more throttle/RPM than usual and ride the clutch to prolong engagement I cannot avoid the bucking, which makes it look & sound like I have no idea how to drive a manual :lol:
The base tune is supposed to be the same as the stock Honda tune, however when I swap in my old stock ECU the problem goes away completely, so there is a difference somewhere.


What "fuel cut" settings are being referred to above?


Kawzx7 also discussed a similar issue in another thread & found his fix by tweaking the tip-in ignition retard.
viewtopic.php?f=13&t=264&hilit=gear+adjustment
Which has me wondering if my issue cannot also be resolved by tweaking the Tip-in gear adjustment multiplier.

Tip-in Gear Adjustment Multiplier (Values)
Gear 0 = -100
Gear 1 = 0
Gear 2 = 0
Gear 3 = 0
Gear 4 = -60
Gear 5 = -100
Gear 6 = -100

Im thinking I may try reducing the 1st gear multiplier from zero to -5 or -10 and see if anything changes (for better or worse), but if I need the tip-in to help with up-shifting should I instead change the gear below?
So to improve shifting into 1st, should I raise gear 0 from -100 to -95 or -90? Or do I split the difference and adjust both gear 0 & 1 to reduce the multiplier delta between the gears

I may need to pick through some datalogs to see specifically when the vehicle recognizes being in first gear and if I can identify this bucking event in the datalogs. I could see the transition between the -100% (no tip-in retard) & 0% (full tip-in retard) multiplier being an issue if the engine is being loaded down by the clutch but since the vehicle is still stationary it hasn't identified actually being in first gear yet.


or maybe I am way off base here :lol:
KTuner
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Re: Bucking in 1st gear stop and go letting off throttle

Post by KTuner »

Pay attention to wideband values and fuel trims.

You can adjust fuel cut if it's related to that. Letting off the throttle won't be tip-in.

The factory tune in the software is the factory tune. That does not mean that your ECU has the same software on it.
Audiophyle
Posts: 76
Joined: Sun Aug 18, 2013 8:16 pm

Re: Bucking in 1st gear stop and go letting off throttle

Post by Audiophyle »

I thought I explained clear enough in my post that it is when accelerating slowly with partial throttle that mine is bucking, not when letting off the throttle. I am aware tip-in is for increases in throttle position.

On a related note however, after switching back to the Ktuner ECU (with reflash tune) the bucking was absent for a couple days and has began to progress, which tells me there is something odd going on that the fuel trims are possibly trying to fix, and is creating the bucking issue. Leaving it alone for now until the bucking gets to where it was before when I swapped ECUs, then I will try datalogging to see if I can identify the actual cause.
KTuner wrote: The factory tune in the software is the factory tune. That does not mean that your ECU has the same software on it.
Can you elaborate on this? Stock ECU & ECU+Ktuner "Stock" tune should operate a stock engine near identically regardless of the difference in software as the mechanical components are the same. Windows 10 runs programs exactly the same as Windows 7 runs them, despite being different systems they share compatibility. I imagine the Ktuner ECU with stock tune should be indiscernible from a stock ECU, assuming both ECUs are originally designed as stock equipment for the same vehicle/engine (which mine are).
KTuner
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Re: Bucking in 1st gear stop and go letting off throttle

Post by KTuner »

Part throttle won't be tip-in either.

Good to hear. You can see fuel trims going to work as well.

Not if there were tune differences between the factory software versions.

More likely is everything is reset when you unplug an ECU and like you said the fuel trims may be adjusting.
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