[Terry335]

Originally Posted by shiv@vishnu

No and no.

Figured as much, you seemed to imply you were doing something with it. I’ve run between stock up to 14psi with only tmap attenuation and haven’t thrown any codes or anything that would indicate a second sensor is watching.

Has anyone checked the part number/specs for the second map sensor? I wonder how much boost it can read? If its actually a 2bar maybe that sensor controls the ECU fueling tables, while the tmap controls the boost regulation system.

[OpenFlash]

Originally Posted by Terry335

Figured as much, you seemed to imply you were doing something with it. I’ve run between stock up to 14psi with only tmap attenuation and haven’t thrown any codes or anything that would indicate a second sensor is watching.

Has anyone checked the part number/specs for the second map sensor? I wonder how much boost it can read? If its actually a 2bar maybe that sensor controls the ECU fueling tables, while the tmap controls the boost regulation system.

As mentioned ealier in this thread, the baro sensor only reads up to a few psi of boost. It is not a 2bar sensor. So as long as you don't tweak the TMAP sensor while the baro sensor is operating within its own range, there is no problem. I'm not sure where I implied that we are manipulating the baro sensor.

[Terry335]

Originally Posted by shiv@vishnu

As mentioned ealier in this thread, the baro sensor only reads up to a few psi of boost. It is not a 2bar sensor. So as long as you don't tweak the TMAP sensor while the baro sensor is operating within its own range, there is no problem. I'm not sure where I implied that we are manipulating the baro sensor.

With this quote:

Originally Posted by shiv@vishnu

The baro sensor does read boost, but only a few psi. So it's important to make sure both MAP sensors provide similar readings up to this point. Or else, a plausability code will be triggered and/or suspicious data will be logged in the ECU.
-shiv

Since the tmap never sees vacuum, I imagine that window is small. FWIW I'm doing a linear attenuation with no codes so the allowable discrepancy range between the two sensors (even at low boost) must be greater than 7-8%.

[OpenFlash]

Originally Posted by Terry335

With this quote:



Since the tmap never sees vacuum, I imagine that window is small. FWIW I'm doing a linear attenuation with no codes so the allowable discrepancy range between the two sensors (even at low boost) must be greater than 7-8%.

It's easy to make sure that the two sensors see the same pressure. And that is by not adjusting the TMAP sensor until the baro sensor hits 5v. Obviously, this isn't possible with your current approach. And if you ever throw a code during this condition (for any reason), the snapshot data that is logged in your ECU will reveal implausable data regardless of whether a implausability code is triggered.

-shiv

[Terry335]

Originally Posted by shiv@vishnu

It's easy to make sure that the two sensors see the same pressure. And that is by not adjusting the TMAP sensor until the baro sensor hits 5v. Obviously, this isn't possible with your current approach. And if you ever throw a code during this condition (for any reason), the snapshot data that is logged in your ECU will reveal implausable data regardless of whether a implausability code is triggered.

-shiv

Actually that's how my beta version worked; I used a 2.4v zener diode to only attenuate the signal above ~2.6v (~4psi). I ended up dumping it after I found the resistors alone worked better from a drivability point of view.

I'll have to manually trigger codes and pull the snapshot data to check that aspect out. Strange they wouldn't use a 2bar sensor there though.