Acceleration Increase Fuel Table (ADD_FUEL)

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modulation
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Acceleration Increase Fuel Table (ADD_FUEL)

Post by modulation » Fri May 30, 2008 11:05 am

From what I read this table adds extra fuel for quick acceleration and uses the TPS as a reference.

Is the Y-axis the amount of addition fuel to add, or is it the TPS voltage value?

On some ka24det tunes I see it changed from 203 to 255 (max value.)
When tuning does anyone mess with this map? If so why do you?
For a NA tune is there any point in messing with it?

JasonKemmerer
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Post by JasonKemmerer » Fri May 30, 2008 5:18 pm

Curious about this too.
Is the Z32 adr "Increase fuel"

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Post by Matt » Fri May 30, 2008 11:37 pm

That is the 'increase fuel'

Whate devin wrote:
One table of interest is the Throttle Enrichment Table. When you stab the gas pedal the TB (throttle body) opens and a rush of air enters the engine. At this point the engine needs an immediate boost in fuel and can not wait for the MAF sensor. So depending upon the angle of the TB an extra amount of fuel is added. From what I have heard the stock Throttle Enrichment Table is very good and it should only be altered on highly modified cars that have been dynod and need specific AFR adjustment. Also the TTP Max helps to keep the Throttle Enrichment from dumping too much fuel at lower rpms.
This topic was never completely finished. The indexes are what I have were RPM from what I did find originally when putting it together but not sure about the meaning of the number itself. Cant find any referenced in the GRID mapmaker to this, or other Japanese documentation. It is something that came from the ROM Editor config files but no real info behind it

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Post by GZ@hybridka » Sat May 31, 2008 4:37 am

I am not sure if this is what you are referencing, but the function of "accel increase volume" commonly found at &H0200 in the 4cyl ecus (ka, sr) is to max the TP load variable used to plot the fuel correction table.

The table (accel increase volume) is indexed with RPM and the data value is compared with the current TPS adc count. If the TPS is greater than the current "accel increase volume" data value, the regular TP used to plot the fuel correction table will be bypassed and a value of &HFFFF (maximum TP) will be used instead.

Basically what it does is shift the plot the the last column. The description provided "accel increase volume" is actually a good one for this function, though I sometimes call it "TPS maxout TP"

Small problem here is that the actual TP is not affected, thus the map trace will not reflect this happening. This is the only condition where TP maptracing will not accurately display the correct location being used by the ecu.

EDIT: I believe this is what the original poster was referring to. Most sr/ka ecus have this set to 203. So when the TPS is 4060mv or above, the ecu will always be using the last column of the fuel correction table.

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Post by Matt » Sat May 31, 2008 2:12 pm

Thanks for the feedback gabe.

So that value 203 * 0.20mv = TPS voltage threshold before using maximum possible TP. Thats an extra translation I can add in the next version :D

I have seen that FFFF assigned to TP in the fuel map code as well as the 'Accel increase fuel' table but didnt know how they were linked

lyckaon
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Post by lyckaon » Fri Aug 08, 2008 10:53 pm

Hi!

Does the CA18DET ECU work the same? The values in the acceleration table are not the same as SR...

If we want to lean a bit "when we floor the gas pedal" we must adjust the last colum (max TP) of the fuel map?

Thanks

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Post by Matt » Sat Aug 09, 2008 6:05 pm

yes you would increase the TPS voltage so when you gun it you dont reach the value in the table before it thinks of it as 'apply full TP'

modulation
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Post by modulation » Wed Oct 15, 2008 6:25 am

Is there any easy way of knowing when the ECU is using this table (increase fuel) to calculate the TP?

Is it normally only used in 1/2 gear? Or is it also used in 3rd?

It's hard to pin down AFR's since I'm not sure if the ECU is using just the Fuel map or if it's also using the increase fuel table.

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Post by Matt » Wed Oct 15, 2008 10:35 am

From looking at the code it is gear independent, and once the TPS voltage for the particular RPM is exceeded then the look up for TP is set to 65535 [255] but not shown up as such in consult as gabe mentioned

There is no real way to display when this is occuring

modulation
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Post by modulation » Sun Oct 19, 2008 2:33 am

Matt wrote:From looking at the code it is gear independent, and once the TPS voltage for the particular RPM is exceeded then the look up for TP is set to 65535 [255] but not shown up as such in consult as gabe mentioned

There is no real way to display when this is occuring
If it isn't too much trouble to figure out from the code what is the TPS voltage required for the ecu to start using the increase fuel table?
I know it's gear independent but is it close to being around a specific voltage?

+4V? +4.3?

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Post by Matt » Sun Oct 19, 2008 9:28 am

I believe that is done already, the current RPM accessed is traced, and then you match the TPS voltage against what the guage is

If it is over then your TP internally to the ECU is at maximum
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acceleration increase fuel
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modulation
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Post by modulation » Sun Oct 19, 2008 11:43 am

Matt wrote:I believe that is done already, the current RPM accessed is traced, and then you match the TPS voltage against what the guage is

If it is over then your TP internally to the ECU is at maximum
Ah I see. Yes that makes it pretty easy to know if the current AFR in the cell I'm in when I play back a log is influenced by the increase fuel table on not..

Thanks!

Edit:
I think I misunderstood what this is used for.
I thought that making the values higher would cause a higher TP and richer fuel mixture on acceleration over a certain TPS value, but instead these values are a maximum threshold of the TPS values to accept before altering the TP with data other then that on the Fuel Map.

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Post by Matt » Sun Oct 19, 2008 11:22 pm

(second paragraph) yes that is correct

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Post by GZ@hybridka » Tue Oct 21, 2008 9:18 am

There are additional TPS based fuel corrections in these ecus as well, but they have to do with transitional issues with the MAF sensor. Basically as you come off the throttle and back on, the rush of air can cause the standard fuel control algorithm to overshoot and rich AF. In such cases the ecu will use a type of alphaN (TPS based) maf emulation.

Throttle enrichment is extremely important with all fuel controllers obviously. The reason we do not have to fiddle with enrichment settings all the time is due to the accurate high response nature of the MAF (aside from condition listed above).

The standard fuel control algorithm takes care of most(all) of the acceleration enrichment.

A speed density system is much slower to react and the volume accuracy is not as fine (after it is calculated). So needless to say a lot of TPS enrichment functions are required with those systems (and they are generally not as efficient)

From what I have noticed, the MAF technology also got better throughout the years, the later model MAF has better response and does not require as much compensation (like first paragraph).

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Post by modulation » Tue Oct 21, 2008 11:24 am

GZ@hybridka wrote:There are additional TPS based fuel corrections in these ecus as well, but they have to do with transitional issues with the MAF sensor. Basically as you come off the throttle and back on, the rush of air can cause the standard fuel control algorithm to overshoot and rich AF. In such cases the ecu will use a type of alphaN (TPS based) maf emulation.

Throttle enrichment is extremely important with all fuel controllers obviously. The reason we do not have to fiddle with enrichment settings all the time is due to the accurate high response nature of the MAF (aside from condition listed above).

The standard fuel control algorithm takes care of most(all) of the acceleration enrichment.

A speed density system is much slower to react and the volume accuracy is not as fine (after it is calculated). So needless to say a lot of TPS enrichment functions are required with those systems (and they are generally not as efficient)

From what I have noticed, the MAF technology also got better throughout the years, the later model MAF has better response and does not require as much compensation (like first paragraph).
Awesome. Thanks for the info.

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