I've read in another thread where it was discovered that the standard "Air Temp Compensation" table is more likely a intake temp vs. voltage scaling.

I am looking for a REAL air temp fuel scaling. Any idea if there are flags in the dissasem that would indicate such a table existing?

I'm tired of retuning for 40 degree temperature swings. When it is 30 degrees out my tune hits 11:1 rock solid, but when it gets up to 70 degrees then that same tune reliably hits 10:1. This is especially unacceptable when I'm racing and intake temps are more like 50-60 degrees higher. With as much as temp swings here in VA I don't want to keep upping and downing my values by ".8" or so just to adjust for temps.

 

Are you using the ecu+ with the GM IAT? GM Maf?

 

afaik (and I could be wrong)

airtemp affects the load variable that the ECU uses for fuel maps (remember there are multiple load variables in the ECU)

ie higher IAT = less load.

 

I observed the same with my load based boost control. The ambient temperatures dropped about 50 degrees in two days and suddenly my rock solid 23 PSI curve (in 70 degree weather) was running a consistent 25-26. I had to drop target loads by 30

 

Hmm, yeah that's what I was thinking Tephra. I'm thinking that if you alter the current "air temp correction" table maybe it will change the air temp the ecu sees which will in turn change the load it uses...... but I don't think that is the best way to do it. I also don't think I'm logging the right load any more. I'm using the oldschool 2 byte I think. If I remember correctly there is a more correct load to log, yes?


Deepnine, yes I do use the ECU+ for logging. I am not using the GM MAS or AIT.

 

There are two air density corrections based on IAT. As tephra said, one is used to calculate load. This one should not be touched. The other one is used to correct the fuel pulse width, and is meant to be adjusted. The adjustable one is already in the ECUFlash definitions in the "Fuel" category. Do you drive an VIII or a IX?

 

I have a VIII. I already have this:



But in this thread: https://www.evolutionm.net/forums/sh...p+compensation
it was pointed out that this was more of a voltage:temp scaling. I'm looking for the map that you speak about which affects injector pulse.

 

Its all coming back to me now. I disassembled this part of the fuel control system many months back. That's the "adjustable" table that I mentioned, however I had forgotten exactly what it does. Now that I look back at my notes, I see that this table is used only to calculate an axis for another table. It is an air density vs air temp table, but it does not have a direct affect on the fuel pulse width. The effect that it has is small and only affects idle and very light part throttle driving. I recommend that it not be adjusted. The other table that I mentioned probably should not be adjusted either. That leaves you without a solution to your AFR variations. There may be another table that affects AFR as a function of IAT. I should probably try and find that some time.

 

That would really be great man. Not all of us live in 70 degree socal.

 

Has anyone else worked on this? I should think everyone has dealt with this problem.

 

Which rom is it for, it really should be listed when requesting info? Just teasing... I saw from an earlier post you use 94170014? Try this and see if it does what you want.


<table name="Fuel Trim vs Air Temp" category="Fuel" address="36dc" type="2D" level="3" scaling="EnrichmentAdj">
<table name="Air Temp" address="689e" type="X Axis" elements="8" scaling="Temp"/>
</table>

 

Dude, thank you! Seriously, has noone used this before? Bryan? Anyone?

Yes I use 94170014. I really was just asking in general to see if anyone had discovered anything of the like, but yeah these values look like what I would expect! I'll give 'em a try here soon.

So it appears that as intake temp increases the value decreases... So if:
A.) The fuel table cell values are supposed to be AFRs
B.) This table is supposed to be a set of multiplier values

Then:
A.) This multiplier table gets applied to the pulsewidth itself, not the fuel map.
B.) Values less than "1" indicate a decrease in IPW by a percentage from what the fuel table would call for.


Summary: So does it work like this: (fuel cell value) X (some formula to get IPW) X (Fuel Trim Vs. Air Temp value) = Output IPW ??

Just want to make sure I understand this before I go trying to change it.

 

MRFred, can we rescale the air temp comp table to a more specific temperature range if the plots fall at the same points, or will it screw it all up?

Another thing, does the MAF smoothing/scaling tables fit into the ecu's load equation? (honki)BTW, the MAF tables can be very useful in fixing uncontrolled AFR swings resistant to the AFR map, (mrfred) I am just curious if these might change load, particularily TAR unit's.

 

what would the code be for the 94170015 ? ? ?

 

I'm not 100%sure but I think it's identical. I plugged it in to check and all the values the table displays come up the same as the picture in honki's post.