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ITB's -TPS load based VE with MAF sensor on Vacuum Chamber

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Hi All , another ITB Question

So I have a V6 running ITB's on a Haltech elite 2000. The current setup runs fine, and it is TPS Load based VE. as there is no "Manifold" the VE calculation uses the atmospheric pressure measured on the onboard MAP sensor that isn't connected to anything so effectively the air pressure part of the VE equation is a constant

Now I've made up a vacuum chamber with 6 ports to try out an idle control valve, since i have the chamber i also added an external MAP sensor to it.

So my question is, everyone says that the signal from the MAP sensor on a setup like this is not accurate enough to run MAP as the load axis, No worries, but even if I use TPS as the load axis the VE calculation will use the value from the MAP sensor now on the chamber.

If its not accurate enough for the load should you not be using it at all and just stick with the atmospheric pressure? or is it more a resolution issue for tuning and the actual signal is still consistent and usable for the VE calculation?

thanks for any input

I think you mean MAP (a pressure sensor) not MAF (a Mass Air Flow sensor).

What does the MAP signal look like compared to your throttle position? Is it smooth or noisey. How responsive is it to fast throttle changes?

Careful design can produce a usable signal.

Share some data to get better input.

Thanks David, you are correct i meant MAP, i blame jet lag....

I haven't run the system with the new chamber yet, but as soon as i do I'll post some data

I was more looking to see what others have done in this situation


The only potential problem I can see with your plan for the vacuum chamber is that you plan on putting an idle vale on it. This will likely mean that you MAP sensor will not read correctly at idle, as your introducing a variable leak in your vacuum chamber with it.

I have done many of these before on a 4 cylinder engine using itb. Using either link g4+, maxxecu, or haltech platinum series. Using MAP as load for lambda table, and TPS as load for main fuel table. It works fine with idle valve and brake vacuum connected to the vacuum chamber. Make sure the hose length from the vacuum chamber to the intake port is all equal and you’re good to go. The only time where MAP sensor doesnt really do a great job is when u are using a huge overlap huge duration camshaft. If youre just using a mild camshaft it wont be a problem with that setup. And make sure the all the throttle blades are balanced using a vacuum gauge.

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