Looks like I need a different matfactor / thermfactor (and maybe airdensfactor too)!
LCD displays -24..-26C air temp instead of -6 .. -8C
The full vems.hex must be uploaded, but only the first part will be changed, 0x0100..03FF
Do you maybe have new tables ready ?
yes i have new tables ready,but i will have to change the whole thing tough,i realised that for proper everyday use i need more VE resolution on the lowboost section,so i have to change the brake points for the VE table.
any update on these??:
-MAT rescale
-MAT ignition retard
-custom oil temp/pressure gauge with V3.3 and LCD
-5 coil tach?
MAT - airdenfactor
At 0 Celsius the displayed MAT is -16 Celsius. Therefore the ECM enriches appr. 6% (as it should, according to the gas-law), this must be fixed.
We really do not want to hack by raping the gas-law. Instead we fix it the proper way, with proper matfactor and airdenfactor tables. See EasyTherm. Note the recommendations for you in factor_notes.txt, I'd use 3300, 270, guess which file: factor_3300_270.hex, this seems to be the best match to your measurements, +21F at lowtemp and +12F at hightemp.
4200,270 might be tempting to get +29F at very low temp, but that curve would also effect your high-temp reading with +26F (instead of desired +13F), and quite bad match to your (appr 3000 Ohm) sensor.
The LCD reading (with a certain, documented factor-file in use) near 80..100C known temp would be useful. The 80C point is not good either since the real temp is "NA" there. Only a point is useful where both real temp and LCD reading is known (preferrably the resistance as well)
When
- -16C (3F) is displayed, internal 43 (0x2B) value is read from adcread position 230.5 (actually, 230=>0x2C, 231=>0x2A)
- however, it should read 0C (32F, internal 72=0x48, which could be read from adcread 201)
This is huge difference (255-201)/(255-231)= appr. 5/2 (*2252 Ohm), so likely your sensor has quite greater resistance than 2252 Ohm.
In this case only this 0C datapoint is just not enough to get good calibration result (it's possible to make it show good at 0C, but we don't want to hide bad readings at higher temp!)
Can you provide another measured data-point ?
Either resistance or temp-reading at known temp.
Should i put the MAT sensor in 100Celsius water??
This would not damage the sensor, the MAT might not be insulated, so it can cheat the measurement.
All i can do is that i put the car in the garage ,where airtemp is approx 18Celsius.
That's nice. Also, at every calibration temp-point (0C and 18C, and maybe 35C when holding in your hand), take note of LCD reading, and preferrably sensor resistance (measured with DVM, sensor disconnected).
The sensor is a regular GM style airtemp sensor,like this one here:
http://www.034motorsport.com/product_info.php?cPath=23_30&products_id=58
Note that these measurements are taken in garage,not in a laboratory,i do not have a special equipment for this,80C measurement was made with boiling water.
Temp in Celsius
Real / LCD / DVM (kOhm) / DVM position / NOTE
0 / -16 / NA / NA /
5 / NA / 5.93 / @20k /
18 / 08 / 4.41 / @20k /
21 / NA / 2.92 / @20k /
35 / NA / 3.17 / @20k /My hand,real temp NA
80 *** / 77 / 0.322 / @2k /HOT water,real temp NA Real temp would be nice, but see below
100 / NA, would be nice / 0.200 / @2k /Boiling water w/ bubbles
The 100C point suggests an appr 3000 Ohm sensor: 200 / 152.75 * 2252 = 2948.60.
From this, we can have a good estimation of the 80C point: 322 Ohm * 2252/2948.6 = 245.93 Ohm for a standard 2252 Ohm sensor, which is appr 84.15 Celsius. This suggests we want +7.2C = +13F at high-temp (so 101C reading ment actual 108C which - if known - would have advantages for the coolant temp, but remember this is all for the airtemp at the moment).
2005-12-31 UPDATE:
tried bot 3000_270 and 3300_270, max MAT increase was 2C with 3300 (from -16C to -14C), but with this i was unable to use MegaTune, because it crashed, i think because firmware version problems ( i used the good one!!).
- upload your edited vems.hex (zipped)
- see IssueReports for the info needed for the report so it can be investigated
OK so here you go:
version v3.3
serialnr 312
firmware 1.0.19
Megatune R27