BARO on E67 for N/A cal that is boosted

[scdyne]

Since the N/A (12610012) E67 calibration is only equipped with 1 pressure sensor that measures BARO on start and MAP during operation, how do people address the issue of BARO getting updated with higher values when entering boost?

My atmospheric pressure at 2200 ' ASL is 97kPa but within a few blips of the throttle my BARO goes from 97kPa to 105kPa and stays like that for the remainder of my engine run time.

How do other people address this or is it just ignored as a limitation of the calibration and everything is configured for 105kPa?

I can see that as you go higher in altitude that this delta between real BARO and what the ECU thinks is BARO could really mess with idle fueling.

Can this calibration (12610012) be fitted with 2 sensors where one is BARO open to atmosphere and the other MAP?

[scdyne]

Bueller ..Bueller ..Bueller ..

[joecar]

I'm researching... and I asked Ross.

[GMPX]

It's probably clipped at 105kPa, but I don't recall under what conditions the ECM updates it or how GM handles it on a factory boosted engine.

[scdyne]

The best I can tell from logs it updates it on a slow map read or averaged over a short period of time around 0.5 sec.

pseudo code

If BARO < 105 Then
If AVG(MAP) > BARO Then
BARO = MAP
End if
End if

So if I just blip the throttle and enter boost quickly it will not bump it up, but if I hold it or go above 105 kPa for any length of time it updates BARO. Eventually after a few blips BARO defaults to 105 and my fuel trims go a little out of whack.

At close to sea level the offset is probably so close it's within the error between fuel injectors, but as you go up in altitude I suspect that this could really become a problem.

For the CTS-V cal it has multiple MAP sensors and I assume that the MAP on the non pressure side of the S/C is the one that is used for BARO.

Just on tuning the injectors I really don't know how to make this as reliable as I would expect to see. Mind you 99% of all people wouldn't care about the detail I'm trying to reach, but I think this makes it very difficult to tune the higher a vehicle is in altitude. Maybe there is another table I'm missing that can address this.??

One of the mysterious problems that has been seen with E67 aftermarket boosted engines is a DTC that causes the automatic transmission to go into limp mode. It says it's a Torque limit related error, but I have done a number of configurations to the Torque settings in the ECU and have not gotten that DTC to go away. Eventually if I transition from low to high and back to low altitude in one engine cycle it fires off the code.