Speed Density 2.0 (3D VE Tables, Baro)
Jul 18, 2016, 09:50 PM
#827
Hey guys. Apologies if this has been answered elsewhere: I'm having a tough time believing my intercooler is so efficient that in 95F weather the max IAT I will ever see is 102F. Even in 75F weather I'm still seeing a max of 102F, so the reading has to be incorrect. I'm using the 0x03 setting on the "SD Convert IAT to MAT" table with a GM IAT and a 4 bar Omni MAP sensor.
I'm thinking I may have to change the voltage scaling for the GM IAT or there may need to be some IAT tuning that I need to be doing. Any help would be greatly appreciated.
I'm thinking I may have to change the voltage scaling for the GM IAT or there may need to be some IAT tuning that I need to be doing. Any help would be greatly appreciated.
Jul 21, 2016, 03:51 PM
#828
I spent a long time trying to get my iat right. i am close by putting the sensor in a known temperature then adjusting the table. i plan to get some hot water and a thermometer to plot out a range of values that correlate to real temp values, but i havent had a chance to do that yet.
unfortunately the numbers ive found dont correlate to each other at all, even the gm temp sensor datasheets that specify temp vs resistance.
unfortunately the numbers ive found dont correlate to each other at all, even the gm temp sensor datasheets that specify temp vs resistance.
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D-VO (Jul 21, 2016)
Jul 21, 2016, 07:34 PM
#829
I spent a long time trying to get my iat right. i am close by putting the sensor in a known temperature then adjusting the table. i plan to get some hot water and a thermometer to plot out a range of values that correlate to real temp values, but i havent had a chance to do that yet.
unfortunately the numbers ive found dont correlate to each other at all, even the gm temp sensor datasheets that specify temp vs resistance.
unfortunately the numbers ive found dont correlate to each other at all, even the gm temp sensor datasheets that specify temp vs resistance.
Jul 22, 2016, 07:02 AM
#831
The easiest way to verify scaling is to log coolant temperature and GM IAT at the same time with key "on" and engine "off" after letting the car sit overnight. Whether its below freezing or 80+ F, my GM IAT sensor always matches coolant temperature within 1 deg F.
Jul 22, 2016, 10:35 PM
#832
The GM resistance data is right on the money, but the scaling in the ECU is established from both the GM sensor resistance chart, the base resistance of the thermistor circuit (2130 ohms for the Evo thermistor circuits), and the voltage of the thermistor circuiits (4.73 volts for the Evo). Quite a long time ago I generated proper scaling tables for the GM IAT in the fuel tank temperature circuit or the IAT circuit. They are right on the money in my experience and were included in all the original 2D SD patches that I released.
The easiest way to verify scaling is to log coolant temperature and GM IAT at the same time with key "on" and engine "off" after letting the car sit overnight. Whether its below freezing or 80+ F, my GM IAT sensor always matches coolant temperature within 1 deg F.
The easiest way to verify scaling is to log coolant temperature and GM IAT at the same time with key "on" and engine "off" after letting the car sit overnight. Whether its below freezing or 80+ F, my GM IAT sensor always matches coolant temperature within 1 deg F.
Jul 23, 2016, 09:34 AM
#833
Is there an "SD how-to" thread? If you mean the thread where I posted the ports of the original 2D SD patch, all those ROMs have the correct GM IAT scaling, although to be honest I don't recall if I put it in the IAT sensor scaling table or the Fuel Tank Temperature sensor scaling table. I guess I'll have to look at some point.
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D-VO (Jul 23, 2016)
Jul 23, 2016, 02:31 PM
#834
Is there an "SD how-to" thread? If you mean the thread where I posted the ports of the original 2D SD patch, all those ROMs have the correct GM IAT scaling, although to be honest I don't recall if I put it in the IAT sensor scaling table or the Fuel Tank Temperature sensor scaling table. I guess I'll have to look at some point.
Jul 24, 2016, 01:19 PM
#836
i searched the forum pretty extensively and found a few different sets of values for the iat table, along with a couple options on what scaling to use in ecuflash. In the end i never got it quite right across the range. I think part of it is the wiring in my car skews the resistance or something.
Jul 25, 2016, 08:39 PM
#837
I guess I may be looking for the wrong information here. Its been a long time since I've installed SD. I didn't know there was an option to use the barometer again, or that there was a harness from spoolinup. I don't know if that harness incorporates the fuel temperature sensor or if there's something else I need to buy to make it work. I guess now there's even more reading to do. Dang it...
Jul 30, 2016, 10:19 PM
#838
The GM resistance data is right on the money, but the scaling in the ECU is established from both the GM sensor resistance chart, the base resistance of the thermistor circuit (2130 ohms for the Evo thermistor circuits), and the voltage of the thermistor circuiits (4.73 volts for the Evo). Quite a long time ago I generated proper scaling tables for the GM IAT in the fuel tank temperature circuit or the IAT circuit. They are right on the money in my experience and were included in all the original 2D SD patches that I released.
The easiest way to verify scaling is to log coolant temperature and GM IAT at the same time with key "on" and engine "off" after letting the car sit overnight. Whether its below freezing or 80+ F, my GM IAT sensor always matches coolant temperature within 1 deg F.
The easiest way to verify scaling is to log coolant temperature and GM IAT at the same time with key "on" and engine "off" after letting the car sit overnight. Whether its below freezing or 80+ F, my GM IAT sensor always matches coolant temperature within 1 deg F.
This is what's going on. Daytime log in Florida today shows 98.6 degree IAT with a 91 degree ambient temp:
Nightime run still shows a 98.6 degree IAT with a 78 degree ambient temp
What I've been trying to do is use the 'Ignition Trim vs Air Temp' table to adjust timing given the current IAT temps so I can always have the highest and safest amount of power available. Assuming this is one of the tables that actually works properly; if the IAT doesn't change the ECU is not able to correct the timing to IAT temps which leaves me at a disadvantage during seasonal temp swings. Should I just go with the pin 77 to correct this issue?
Thanks
Last edited by D-VO; Jul 30, 2016 at 10:46 PM.