TMAP After TB?

[Indy135i]

Anyone know if it’s possible to run the TMAP sensor AFTER the throttle body rather than in the charge pipe? I’m welding a water to air manifold (no comments about the controversy around water to air please) and realized the TMAP isn’t gonna work properly in the charge pipe since the intercooler won’t come into play until after the TB thus IAT needs to be measure near the runners of the IM.

 

[chrisdf]

If the intercooler is between the TB and the intake, where are you going to sense the IAT? I assume the ecu needs to know the temp and pressure at the same time to calculate the air density. There’s no mass air flow meter.

 

[Indy135i]

If the intercooler is between the TB and the intake, where are you going to sense the IAT? I assume the ecu needs to know the temp and pressure at the same time to calculate the air density. There’s no mass air flow meter.

Exactly, I'm hoping to move the TMAP to the front of the intake manifold right next to the runners. This will be similar to a B/S58 manifold. I just need to know if, with N54, I won't have any issues putting it after the throttle body (will the ECU care or even know?).

 

[doublespaces]

I thought people already did this before. Pretty sure there was a throttle body T adapter or something.

One benefit to this was you eliminate the throttle closure blips. Can't remember if there's downsides. You'll be measuring vacuum this way too.

 

[carabuser]

That will confuse the DME. Don't think it'll work too well.

 

[Indy135i]

That will confuse the DME. Don't think it'll work too well.

Yea this was my initial concern which is why I asked but I'm not so sure. If the car is running then the throttle body is always open, even partially at idle, no? In which case pre and post TB should be the same atmospherically and the data the TMAP is seeing should be the same either way shouldn't it?

 

[Indy135i]

Maybe I just pick up a redundant TMAP sensor (or someone can send me your stock one if you've upgraded ) and I can install it post charge cooler but only use the temperature wire. Still install my 3.5 bar TMAP in the charge pipe but disconnect the temperature wire from it and plug in the temp wire from the redundant TMAP sensor downstream post-intercooler?

 

[wheela]

Maybe I just pick up a redundant TMAP sensor (or someone can send me your stock one if you've upgraded ) and I can install it post charge cooler but only use the temperature wire. Still install my 3.5 bar TMAP in the charge pipe but disconnect the temperature wire from it and plug in the temp wire from the redundant TMAP sensor downstream post-intercooler?

That's an interesting idea

 

[Indy135i]

I figured someone on here would have more insight into how this would function. More of the of experts seem to be here than Facebook groups.

 

[carabuser]

Yea this was my initial concern which is why I asked but I'm not so sure. If the car is running then the throttle body is always open, even partially at idle, no? In which case pre and post TB should be the same atmospherically and the data the TMAP is seeing should be the same either way shouldn't it?

When the throttle is anything but 100% open, you'll get higher pressure before the throttle as it acts as a restriction.

It'll probably just make the car really jerky at part throttle. The DME models the manifold pressure based on the assumption that the tmap is pre throttle when in boost.

 

[Indy135i]

When the throttle is anything but 100% open, you'll get higher pressure before the throttle as it acts as a restriction.

It'll probably just make the car really jerky at part throttle. The DME models the manifold pressure based on the assumption that the tmap is pre throttle when in boost.

Thanks. I did more digging on the b58 logic and it does take MAP from the charge pipe and only temperature from the manifold post-intercooler so I think I'm just going to have to go with my plan of action above.