Separate Decel TpsDOT threshold ?

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lagos
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Separate Decel TpsDOT threshold ?

Post by lagos »

Is it possible to add a separate tpsDOT threshold for the decel fuel amount ?

It is my understanding that this value currently gets triggered by the the single acceleration threshold, and this can be problematic when trying to tune out the back fires that can happen with changes in throttle.

My accel threshold is currently set at 15 and I need a decel of 90, but I would like to have that value triggered at a much larger tpsdot of -100 so that it doesn't cause drivability issues that occur from being triggered at 15.
PDX5
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Re: Separate Decel TpsDOT threshold ?

Post by PDX5 »

Are you aware of the Decel Fuel Amount setting?
lagos
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Re: Separate Decel TpsDOT threshold ?

Post by lagos »

PDX5 wrote:Are you aware of the Decel Fuel Amount setting?
Yes, but it gets triggered at the same threshold as acceleration. It causes all kinds of unsmoothness when you use settings of 90 or lower.
PDX5
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Re: Separate Decel TpsDOT threshold ?

Post by PDX5 »

lagos wrote:It causes all kinds of unsmoothness when you use settings of 90 or lower.
That's also what the manual states. Anything below 95% can cause drivability issues on a manual transmission vehicle.

So you're decel fuel is below 90? Fuel map and EAE tuned well?

I don't think a separate decel TpsDOT is the answer here since there is plenty to work with already. I'm curious what your engine setup and vehicle use is.
ol boy
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Re: Separate Decel TpsDOT threshold ?

Post by ol boy »

How noisy is the TPS line? My threshold for accel is down around 25%/sec. My decel amount is set to 70%. My auto trans drives like a man trans as the TCC is lock most of the time.
306 SBFord, Torquer II EFI intake, 60 lbs injectors, 8 LS2 coils, VS Racing 7668 turbo, 4R70W, MS3x fw1.4 w/built in trans controller.
lagos
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Re: Separate Decel TpsDOT threshold ?

Post by lagos »

ol boy wrote:How noisy is the TPS line? My threshold for accel is down around 25%/sec. My decel amount is set to 70%. My auto trans drives like a man trans as the TCC is lock most of the time.

Its not noisy at all. I can get the threshold down to 10%sec or less.

The problem is that at settings like 70% you are going to pull 30% of fuel with those small 10-25%sec changes in throttle. If that setting had its own threshold, you could have a separate trigger point for deceleration where a much larger change in throttle of 100+%sec would be needed to trigger that kind of fuel removal. This would fix all of the problems with using that setting on a manual trans car. Personally if I got below 90ish the car gets all choppy at part throttle driving.
suberimakuri
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Re: Separate Decel TpsDOT threshold ?

Post by suberimakuri »

Put a bit more fuel in the tank, leave it at 100% and be done with it?
I used to play with decel, but don't see the reason anymore, hardly affects economy as the AFR goes lean when back off anyway, plus like you say, can buck if go low.
What does it really achieve in a manual?
lagos
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Re: Separate Decel TpsDOT threshold ?

Post by lagos »

suberimakuri wrote:Put a bit more fuel in the tank, leave it at 100% and be done with it?
I used to play with decel, but don't see the reason anymore, hardly affects economy as the AFR goes lean when back off anyway, plus like you say, can buck if go low.
What does it really achieve in a manual?

1. if you set this at 100%, the car will back fire when you ease off the throttle.
2. this richness between shifts bogs the engine and and reduces turbo spool, making for a slower car between gear changes.

I think MS3 code has solved this issue by allowing you to actually tune negative tps dot values. I would be great if this was ported over or at least a separate tps dot threshold was added.
pit_celica
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Re: Separate Decel TpsDOT threshold ?

Post by pit_celica »

I think your best bet is to tune EAE. Your overall accel/decel control will be much more precise once fully tuned.

Sam
lagos
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Re: Separate Decel TpsDOT threshold ?

Post by lagos »

pit_celica wrote:I think your best bet is to tune EAE. Your overall accel/decel control will be much more precise once fully tuned.

Sam
I had tried that before, but in all honesty it takes quite a bit of time to do. I also feel like I get a crisper throttle response with the basic setting. Just need more control over the deceleration portion of things.
16vboost
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Re: Separate Decel TpsDOT threshold ?

Post by 16vboost »

Using the current code, EAE will be your best solution. Sadly, it's a pain to tune right. But once tuned you can get really good results like this:

Image

I use TPS AE to help EAE on quick throttle stabs but no TPS decel. EAE is running the PW to zero between shifts (then over run fuel cut kicks in to keep it at zero).

-Alex
lagos
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Re: Separate Decel TpsDOT threshold ?

Post by lagos »

That is insanely good except for that initial lean spike. I have attemped to tune it in the past but its an extremely time consuming effort with just one person in the car.

My enrichment is pretty good with the basic settings, but deceleration is lacking due to it being a single value that can't be adjusted too far.
I noticed that MS3 allows you to tune for negative tps dot values. It would be great if this got ported over.

Any chance of getting this feature ported over, oh supreme firmware developer(s)?
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