Not 100% sure what it's called, hopefully you can Help.

[Grashopr]

I am completing a project that requires me to substitute one type of automotive-style sensor for a completely different automotive-style sensor (a Throttle-Position-Sensor for a Pressure(boost) Sensor) The output voltage of the Pressure Sensor is read by the ECU, and ranges from 2.0 to 5.0v, but the output of the TPS under normal circumstances is 0v to 1v. Would a switching regulator take the voltage from the Boost Sensor and produce an output voltage similar to the TPS? I really appreciate any help you all can give me. If any part of this doesnt make sence, or if you need more information, just let me know. Thanks!

Phil
grashopr@mchsi.com

 

[melone]

Why would you have to do this?

 

[felixc]

If I understand what you're trying to do, you need to be sure that the polarity of both sensors go in the same direction. A wide-open throttle will correspond to zero pressure and a closed throttle will correspond to a vacuum. Other than that, probably that an op-amp would do the job to offset, change polarity if needed, buffer your signal to match the the desired range. The linearity may be a different story though. The pressure change vs throttle position relationship may not be linear.
My old Renault Alliance with a single-point injection had no throttle sensor (but two switches for closed and full open position), but just the manifold pressure sensor to do its injection job. It delivered 58 mpg.

 

[VEBill]

"...a closed throttle will correspond to a vacuum."

Sometimes, and then only to varying degrees. Obviously it depends upon how hard the engine is sucking on the other side of the throttle plate. Going down a steep hill at 6,000rpm will draw a bigger vacuum than would idling.

By the way - why is the sensor a "(boost)" sensor ?

 

[Grashopr]

I have been given the project of putting a turbo on a motorcycle with fuel injection. The turbo itself was easily mounted and setup, however the fuel controller is a bit of a pain. There is a company that makes "performance modules" for this motorcycle that allow a user to log in and add or subtract fuel dependin on RPM and Throttle Position. I am attempting to use this Performance Module as a boost fuel controller by substituting the TPS input for a boost sensor input. The TPS uses (if I remember right), a 0-voltage output for 0% throttle, and a 1V output to show 100% open throttle. The boost sensor will show varrying amounts of voltage output depending on how much pressure is applied to it, (which I will find out this weekend), but I need to make a converter that will change whatever the output voltage is of the Boost Sensor to read between 0 and 1v for the input of the Performance Module. Then I will be able to log into the PM, alter the fuel map depnedent on boost and not have to build my own controller.

an Op-Amp would do this? I'll look around to see what kind of a circuit I can come up with. If anyone has any more input on this, I would be very grateful. Thanks!

 

[OperaHouse]

A friend of mine designed this system for a company. I was quite impressed with the ease of his solution. Of course, it would be bad form to give you his solution. I will say that you seem to be on the wrong track.

 

[Grashopr]

Oh boy..that's not good news. There's something easier?? Drats, I really thought I had come up with something here. Well, as it stands, either I dont have the training, or the foresight to see any other viable options besides scratch-building a controller that would measure boost and RPM and alter the pulse/width of the injectors to add fuel. I REALLY dont want to do that, as the rest of this entire system is in 'test' mode right now, and I'd like to try to keep as few variables as possible. Thanks for making me feel unconfident though.

 

[Grashopr]

A VOLTAGE DIVIDER!!! GAWD I should have seen that one...argh!! Thanks for sending me back out to look some more.


The 'hoper