Appauldd

iTrader: (22)

Yeah i figured it out after I tried it.

I wonder if this can cure my cars bad cold running characteristics. My car likes to run super lean when it is cold. I have to rev it in order to get it to run normal. This only happens until it warms up. When it goes lean it bogs really bad.

THUB

iTrader: (5)

I'm wondering if this will make my ECU boost stop wildly overshooting (3+ PSI) when the temp. drops. I wish I had a brain...

mrfred

iTrader: (50)

THUB is correct, this the air density vs air temp table used to calculate air temp compensated load. I took another look, and it is also used in the IPW calculation, so it could be used for what you want. The stock values in the table exactly follow the ideal gas law. I'd be very careful about changing this table as I'm pretty sure that the table was not intended to be changed. It will affect IPW and temperature-compensated load (and a few other things I haven't bothered to disassemble). You would want to decrease the values in the table corresponding to cooler temperatures. This will cause temperature-compensated load to go down and cause your IPW to go down because the ECU will think there is less air going into the ECU.

honki24

iTrader: (23)

So then this table is not as I supposed. Yeah, I don't want to change the ECU's perception of air density. I'm sure that is correct enough. I am, however, looking for the way that the ECU must compensate IPW for varying air temps. In that mess of flags and such do you see such a table? I don't really want to "trick" the ecu into doing what I want, I'd rather adjust the correct variables.

Could you, as plainly as possible, write out a mathematic equation that details how the ecu is deciding what IPW to use?

IE: (Fuel tabel value) X (fuel trim vs. air temp value) X (some constant) = IPW


Also, I've never really gotten into MAS tuning... do tell how it can affect temperature compensation.

Mattjin

There is nothing really wrong with using the table so dont be scared off. I have experimented with it and although it is linked in with code for density calculation, its primary effect is to vary IPW with air temp changes. I would not make large changes to it however, just try small changes and see if it responds how you wanted.

I think your maths table might be alot larger than what you are thinking :-)

Appauldd, I would not use it for cold start issues. It is an air temp table, not an engine temp table. When your engine is warm but the air is cold then you use this table.

honki24

iTrader: (23)

Yeah, I'm sure my "math" equation is over simplified. lol I just doubt I'll understand it if someone tries to explain all this in code lingo. Math = universal language.

If you're confident it doesn't affect anything else in a serious way then I'll give it a shot.

C6C6CH3vo

iTrader: (9)

That's weird, your temp is scaled to 41C, mine is to 86C but the units are the same. I wonder if it's an address thing and the actual IAT volts are same.

When reading temp as volt 16 do you think these could be the actual volt scales? Awful close to my IAT volt logs (2.1 - 1.9v on a cool day)

BTW Iv'e been messing with this table for years, never really took the time to see what it fully does but I remember there was a time I managed to get stable gear dependant AFR - wonder if it was from this table before I defaulted back to the stock one

Mattjin

I would not be surprised if the map I posted is a baseline calculation for changes in Air Temp because it does seem to be mapped scientifically (based on 25C room temp) and not tuned to suit the car, but the other map is used for corrections to this map so that it does suit the car..... if you understand what I am getting at. I just haven't bothered spending any large amount of time on the code, rather I spent time in the car testing it and it responds as expected. Changing either of them would probably achieve the same result. This map is what more closely mirrors what we see in the aftermarket as a fuel trim vs air temp, but one day if someone has time we might find out how deep the rabbit hole goes.

C6C6CH3vo

iTrader: (9)

Just added math to the OBDII logged air temp channel (0..5v) to correspond to the ecuflash's uint16 derivitive. Done by MC(uint16;0;128; )=(Intake_Air_Temp/0.0195) and now the logs correspond closely to what I think ecuflash is scaled to.

Since obdII logs (in LW, can't vouch for others) arent exactly precise, I just may have to spend 129 bucks for an additional sensor interface to digitally log the 0..5v data directly, as well as baro among other things (exh psi, timing).

honki24

iTrader: (23)

Or you could look into an ECU+. You won't regret it.

honki24

iTrader: (23)

According to the findings here: https://www.evolutionm.net/forums/sh...p+compensation

The original air temp compensation table only adjusts logged air temp... and does not affect fueling. That's what his graphs appear to show anyways. I believe he concluded that this table was more of a voltage to temp scaling table and that it did not significantly affect AFR.

C6C6CH3vo

iTrader: (9)

Both my kids have braces on their teeth, one ECU+ purchace would set me back two months, I'll have to pass up the offer. Need new tires anyway, no traction, car kicks out in 1st and 2nd .

Back to your topic, I guess we can assume that at least one variable of baro and temp is related to 0..5v which kinda makes it easy with no load to worry about

mrfred

iTrader: (50)

ok, I thought about this a little more, and there may be a way to tune the airflow rate calculation without using the air density table that affects the load calculation. The air temp compensation table included in the early versions of ECUFlash (pre v1.35) that you keep mentioning does not affect logged air temp and will not provide any sort of air density compensation. The ECU looks up an air density from that table to calculate a correction to airflow per Hz value using this table:



Airflow per Hz is used to calculate the fuel pulse width. The values looked up in this table are multiplied with the raw airflow per Hz value to provide a way to adjust the airflow per Hz value based on air density. The air density value is on the horizontal axis of this table (i.e., 0.53, 0.78, 1.03, 1.28). Higher numbers correspond to cooler air temperature (air is more dense when cooler). I choose the scaling so that an air density of 1.00 corresponds to 0 deg C (32 F) and 1 bar (1 ATM). As can be seen in this table, the MAF Hz scale range only goes to 201 Hz. This basically covers idle and maybe very light cruise, so this table was probably meant to only be used to tune that range of airflow rates. However, it could be used to tune airflow per Hz at higher airflow rates because the ECU will use the value at 201 Hz for all airflow rates above 201 Hz.

So what you could try doing is tuning the bottom row of values in this table. If AFR is going from 11:1 at say 75F to 10:1 at say 40F (10% difference in fueling) then you'd want to insert a value of ~0.9 in the two locations I have highlighted in the above table. This will reduce the airflow per Hz value by 10% and therefore also reduce the fuel pulse width by 10%.

C6C6CH3vo

iTrader: (9)

So is that the same baro comp table (found on all ecuflash versions) but with rpm instead of air? If so, does any have the coorect 96420007 addresses?

What is the difference between pre/post v1.35? Mine are the same except the comp title is shaded blue.

Thanks

honki24

iTrader: (23)

Could you identify the XML code needed to see that table on the 94170014? Your explanation sounds like what I'm looking for.

Question on the scaling: So your X axis scaling is basically "% of 0*C" or "% of 32*F" right?

-If so then the far right column would be = 41*F.
--I need to make adjustments between, say, 20*F and 120*F. Could I change the X axis values to "0.625, 1.67, 2.71, 3.75" ? This would mean I could adjust fuel scaling at "20*F, 53*F, 87*F, 120*F" respectively which would be much more helpful than between 15 and 40 degrees.


(note: Your example is for 11:1 at 75* and 10:1 at 40*, but that is an inverse relationship. AFR richens as temp goes up.)