Inconsistent Target AFR

[inj gtr202]

just for your information, your Target AFR table from what i can recall of the A5 tune was screwed with!

i've been thinking about it and how to get it right, only thing i can think to do is get an area, say for example 3600rpm 100kpa, its 11.90 AFR .... i'd think more like 12.6-12.8 would be what you want, so you need to change the table to that .... BUT if you do this you'll lean out that point, so what i'd then do is 12.8 / 11.9 = 1.08 ... so then go to the same point in the VE table and multiply its number by 1.08 (add 8% more fuel).

this is a pain in the ass process, but if you look at the original OSE12P AFR table its nothing like yours.

and i have a feeeling your tune will not be actually commanding the AFR's that are in the table, more so its been fudged to get the AFR's reading right on a dyno or similar.

Yes I was thinking of doing something along these lines, so that my actual AFR somewhat matches my Target.

Yes the AFR targets have no doubt been fudged to get a nice actual AFR on the Dyno.

My plan was to get $12P to run exactly the same as my $A5 chip regardless of what the numbers are.... just a straight copy. Then go about making it more user friendly (ie. make the VE and the target table match up to the actual numbers coming out the tail pipe.)

[inj gtr202]

The inverse temp table is part of the charge temp calc and where you want to play to make the AFR correct for all temps. A MAP sensor based ECU works on the ideal gas law, but for the processing power of the CPU its too slow to calc on the fly, so a table is used instead. There have been a few posts on it, but its prob more info than you need to know ..
https://pcmhacking.net/forums/viewtopi ... gas#p17969
https://pcmhacking.net/forums/viewtopi ... gas#p16809

Thanks,
Makes a bit more sense now.
Although I would have expected a more leaner mixture with a high MAT value, not a richer one, as you can see from the log files straight after start up the target AFR is really low. Then after a min or 2 the MAT temp comes down and the mixture leans out. (Note the coolant temp hardly changes).

How sensitive will the table values be?

[Holden202T]

yeah i know what your saying, i guess you need to work out when you do it cause if you change heaps of stuff with the MAT offsets and such it might change things when you do the AFR table then have to re-visit tables again.

[inj gtr202]

Had a bit of a play tonight with the Inverse temperature term vs charge temp table with mixed results.

I increased the numbers in the Degrees K column and it leaned out the tune.... (wrong way obviously)
So I then significantly decreased the numbers in the Degrees K Column and it did fatten up the tune a little, but wasn't the result I was hoping for. (It still leaned out up the top as the air temp dropped ever so slightly).

So I went hunting though the tables of my old $A5 Tune looking for any other reason (or difference) which will cause the &12P to lean out and the $A5 to be sweet as.

I found that the Coolant Advance vs MAP and TEMP where very different
ESC Attack rate was slightly different

Now with the ESC recovery rate. $A5 measures it in %/sec whereas $12p does it in Deg/200Ms. If I convert my $A5 number of 39.06%/sec to Deg/200Ms I end up with a very different number to what is currently in the tune. It will be going from a value of 1.05 to 28.1232.

The biggest difference I found was in the $A5 Inverse tempature term vs Charge Temp table.

Degrees K 5000/Value = Degrees K x
-40 -38.26
-28 -32.62
-16 -26.69
-4 -19.19
8 -21.74
20 -20.47
32 -19.19
44 -20.47
56 55.95
68 67.14
80 79.11
92 91.96
104 102.94
116 114.6
128 127
140 140.22
152 150.73

Any Comments or advise of what any of these numbers mean how they would affect the tune would be great.
If you want a copy of the $A5 let me know.
Thanks
Adam

[charlay86]

the °K column is used for the charge density calculation, if you lower these values it will think the inlet air temperature is lower which means it has a higher density (in this case quite a lot higher!).
so.. lower air temp = Higher density = more air = more fuel which is what you are seeing.

[inj gtr202]

the °K column is used for the charge density calculation, if you lower these values it will think the inlet air temperature is lower which means it has a higher density (in this case quite a lot higher!).
so.. lower air temp = Higher density = more air = more fuel which is what you are seeing.

So assuming the table is not an error. Every time my charge temp goes between 55 and 45 deg K, there is going to be a massive fluctuation?
the table didn't post as clear as I hoped.
should read
left.............................right
Degrees K .................... 5000/value = Degrees K

[charlay86]

So assuming the table is not an error. Every time my charge temp goes between 55 and 45 deg K, there is going to be a massive fluctuation?

Yeah I'd imagine things would get pretty lean once you approach 55°

I'd say the table has been adjusted to richen everything up, the KINJFLOW and VE table are really where those changes should have been made though.

[inj gtr202]

So assuming the table is not an error. Every time my charge temp goes between 55 and 45 deg K, there is going to be a massive fluctuation?

Yeah I'd imagine things would get pretty lean once you approach 55°

I'd say the table has been adjusted to richen everything up, the KINJFLOW and VE table are really where those changes should have been made though.

I guess that would explain why my old tune used to be on the rich side during winter.
I'll plug tho's values is and see how it behaves.

I'm aware this tune has been fudged in the wrong way. I'm trying to get an exact duplicate because it's a dyno proven safe tune. Once I get enough logs and data from it I will then go about making it right.

I have previously done a $12p tune from scratch and it never felt as fast as my original.

[charlay86]

using 101.3kpa as the pressure, we can roughly calculate what effect the changes in this table will have on the fuelling.
the density % increase is approximately how much extra fuel it is adding based on the altered temperature.

Code: Select all

      input		     output	       Density
Density  ° C	  ° C	Density	% increase
1.51 	 -40	-38.26	1.503	 -0.73
1.44 	 -28	-32.62	1.467	  1.88
1.37 	 -16	-26.69	1.432	  4.30
1.31 	  -4	-19.19	1.390	  6.03
1.28 	   8	-21.74	1.404	  9.43
1.20 	  20	-20.47	1.397	 16.03
1.16 	  32	-19.19	1.390	 20.14
1.11 	  44	-20.47	1.397	 25.52
1.07 	  56	 55.95	1.073	  0.09
1.04 	  68	 67.14	1.037	  0.19

[inj gtr202]

using 101.3kpa as the pressure, we can roughly calculate what effect the changes in this table will have on the fuelling.
the density % increase is approximately how much extra fuel it is adding based on the altered temperature.

Code: Select all

      input		     output	       Density
Density  ° C	  ° C	Density	% increase
1.51 	 -40	-38.26	1.503	 -0.73
1.44 	 -28	-32.62	1.467	  1.88
1.37 	 -16	-26.69	1.432	  4.30
1.31 	  -4	-19.19	1.390	  6.03
1.28 	   8	-21.74	1.404	  9.43
1.20 	  20	-20.47	1.397	 16.03
1.16 	  32	-19.19	1.390	 20.14
1.11 	  44	-20.47	1.397	 25.52
1.07 	  56	 55.95	1.073	  0.09
1.04 	  68	 67.14	1.037	  0.19

That is cool!!

if it only adds the 25% where I need it to (about 3,500rpm and up) it would be about right.