Throttle Position Sensor (TPS) voltage range

[Dr J]

The exact kind of diode is not very critical. You can try an IN4001 which is pretty common. It is good for 1 amp. I don't know how much current the TPS sinks but sensors should be relatively low current. If you have an ammeter, you can disconnect the TPS ground wire and put the ammeter in between the ground wire and an actual ground surface on the vehicle to see the current. If it's higher than 1 amp, just source the diode to handle the current, as that is the only real specification you will need to meet.

[Lapkritis]

A diode is a basically a check valve for electronic current. If you're looking to increase ohms of resistance you will need a resistor. Getting real rough you would simply add a resistor (not a diode) of the value difference from 5v to your real world wot reading. Ohms law...

Ohm's law - Wikipedia, the free encyclopedia

[K Sykes]

The OP is trying to go up in voltage, not down, hence the diode suggestion.

Having said that, mmasse, still would urge that you look at a software solution. It should be a pretty trivial exercise. Also, are your tables only based on TPS? Or do they also use MAP? In many cases, TPS only drives acceleration enrichment and the VE table is driven off of MAP. In any case, the tuner you are planning on using should be able to calibrate the TPS in a minute or two. Last suggestion, have you checked with the manufacturer? They might be able to point you to a calibration tool in the software.

[mmasse]

Kinsley,

Thanks for your input. Regarding the software solution, it will not solve the problem in my case. The issue is that I am using a piggy-back Unichip which modifies the base maps on the Motronic. I can modify the value for TPS on the Unichip, but this will not make the Motronic work on the WOT maps.

Do you know if the OEM Motronic for the 993 uses the TPS at all in order to trigger the WOT maps. If it is only MAF/MAP based then TPS will not be an issue at all.

Thanks again

[Lapkritis]

Originally Posted by K Sykes

The OP is trying to go up in voltage, not down, hence the diode suggestion.

Having said that, mmasse, still would urge that you look at a software solution. It should be a pretty trivial exercise. Also, are your tables only based on TPS? Or do they also use MAP? In many cases, TPS only drives acceleration enrichment and the VE table is driven off of MAP. In any case, the tuner you are planning on using should be able to calibrate the TPS in a minute or two. Last suggestion, have you checked with the manufacturer? They might be able to point you to a calibration tool in the software.

Yep, I thought of that this morning. The 5v source is constant from the ECU. I would put a multimeter on and read the voltage across each pin. Might be a bit of corrosion in the harness or at the wire connections between the feed pin and the ecu.

[mmasse]

Input is 5 volt as per multimeter, so that not the problem
I also tested a spare TPS and same thing