Hall Effect Throttle Position Sensor
This installation description is thought to be accurate but there is no guarantee that this is the case. Anyone using this infomation to install an Hall effect TPS must exercise their own judgement . They use it completely at their own risk. Unless the prospective installer has experience with electrical circuits they are advised to use a competent person.
The standard Throttle position Sensor (TPS) used on the Chimeras and Griffith are a rather crude affair being simply a carbon track with a slider, similar to a volume control on a radio. As the slider is constantly rubbing the track wear is inevitable and as radio volume controls become noisy after years of use a similar problem can occur with throttle sensors resulting in noise or unwanted signals being transmitted to the ECU or even worse a break in the track. High performance cars used in competition have for many years used superior TPS's that are based on an Hall effect device that produce a voltage output that also varies with rotational position but is generated by magnetic interference so is not dependent on contact to a carbon track, they are therefore much more reliable and have a much longer life. Another reason to try an Hall effect TPS was the fact that the original carbon track TPS are no longer available and those available have to be modified for use on the Rover V8 so are expensive.
Several years ago Hall effect (H E) TPS's became readily available and were adapted by a few companies for use in TVR's, an enterprising German TVR owner also adapted one for his car and had a few more produced for TVR friends etc. as he has long since sold his car I managed to obtain one to try. The H E device is made by "Penny and Giles" a high class manufacturer of faders for Broadcast and position sensors etc. but in its basic form it has to be modified by the addition of some metal components to interface with the TVR V8 Plenum. An original carbon track and a modified HE TPS are seen below: The HE TPS connections are; White=Signal; Red =+ve Supply; Black=Earth, the Yellow wire is for a second signal output but is not needed for a TVR.
The standard Throttle position Sensor (TPS) used on the Chimeras and Griffith are a rather crude affair being simply a carbon track with a slider, similar to a volume control on a radio. As the slider is constantly rubbing the track wear is inevitable and as radio volume controls become noisy after years of use a similar problem can occur with throttle sensors resulting in noise or unwanted signals being transmitted to the ECU or even worse a break in the track. High performance cars used in competition have for many years used superior TPS's that are based on an Hall effect device that produce a voltage output that also varies with rotational position but is generated by magnetic interference so is not dependent on contact to a carbon track, they are therefore much more reliable and have a much longer life. Another reason to try an Hall effect TPS was the fact that the original carbon track TPS are no longer available and those available have to be modified for use on the Rover V8 so are expensive.
Several years ago Hall effect (H E) TPS's became readily available and were adapted by a few companies for use in TVR's, an enterprising German TVR owner also adapted one for his car and had a few more produced for TVR friends etc. as he has long since sold his car I managed to obtain one to try. The H E device is made by "Penny and Giles" a high class manufacturer of faders for Broadcast and position sensors etc. but in its basic form it has to be modified by the addition of some metal components to interface with the TVR V8 Plenum. An original carbon track and a modified HE TPS are seen below: The HE TPS connections are; White=Signal; Red =+ve Supply; Black=Earth, the Yellow wire is for a second signal output but is not needed for a TVR.
Original Carbon Track TPS
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Hall Effect TPS
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Modifications for TVR
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The original TPS for the TVR V8 engines had to meet particular requirements for the ECU, it has a travel of 90 degrees to track the throttle shaft movement and its voltage output must vary from about 0.3 volt at idle to around 4.95 volts at full throttle.
The carbon track TPS meets these requirements by having a 90 degrees movement and a track resistance of 5 k Ohms connected between a regulated voltage of 5 volts and earth from the ECU.
The required 0.3v minimum is met by rotating the TPS on the Plenum. This 90 degree rotation and the 5 volt swing has to be met by any H E device. The Penny and Giles part number: TPS280DP (special order) can meet these specifications. This device requires either a 5volt regulated or an unregulated 9-30 volt supply. The HE has 360 degree continuous rotation but with a 90 degrees active segment so needs alignment on the plenum. It is also dual output but the Rover V8 only requires one, the yellow signal wire being unused. The original carbon track TPS has spring tension forcing it against the throttle stop the HE does not but users report no problems in practice. Unfortunately the current drain of this H E TPS exceeds that of the carbon TPS so the regulated 5v supply on the TPS 3 pin socket from the ECU cannot be used and another voltage source is required. I was also hoping that the original ECU earth on the 3 pin TPS socket could conveniently be used but as this earth is shared with other sensors using it caused the coolant temperature sensor to misread. A convenient 12 volt supply is however available from the fuel injector on cylinder number 1. As this is the main 12 volt rail feeding many other components it will be unaffected by the small current the HE TPS draws (about 9mA). A convenient earth is on the Plenum via the corner Allen bolt. The 12v supply has a bullet connectors to enable quick disconnection.
Installation
I chose to reuse the original carbon TPS econseal 3 pin socket on the loom with only the signal wire being connected to the socket central green wire ( if you have an earlier car with the RISTS 3 pin round socket it would be the red wire) so that the original carbon track TPS can always be plugged back in if necessary as a working spare. A capacitor is required between the signal output and earth to maintain the signal output during cranking so this needs to be mounted securely. A small plastic box with an internal tag block is a convenient and neat way to keep things tidy. Offer the HE TPS to the plenum, the brass shaft locates in the throttle slot, this may take a bit of patience and will be correct when the aluminium plate is flush with the plenum face. Connect the signal output to the original TPS socket and check that the new 12v supply, the capacitor and new earth are correctly wired. Turn the ignition On but do not start the engine. Measure the voltage between earth and the white TPS signal wire it should track from around 0.3 volt at idle to about 4.95volts for a fully open throttle.You may need to rotate the TPS to achieve these figures. If the volts are reversed i.e. from 4.95 at idle etc. the TPS will need taking off the aluminium plate and turning through 180 degrees. As a final set up carefully rotate the TPS until about 0.34volts is seen in the idle position, this may be verified on Rovergauge as 5-7% and ensures that the ECU recognises that the TPS at its minimum position is at idle otherwise if the voltage is lower the ECU may throw a fault code and adopt open loop control. The capacitor will ensure that the ECU sees the 0.34 v signal output from the TPS during cranking, its value is not critical but 220uF and 25 volt working was fine, note that the capacitor is polarity sensitive, the negative end is clearly marked and connects to earth.
The carbon track TPS meets these requirements by having a 90 degrees movement and a track resistance of 5 k Ohms connected between a regulated voltage of 5 volts and earth from the ECU.
The required 0.3v minimum is met by rotating the TPS on the Plenum. This 90 degree rotation and the 5 volt swing has to be met by any H E device. The Penny and Giles part number: TPS280DP (special order) can meet these specifications. This device requires either a 5volt regulated or an unregulated 9-30 volt supply. The HE has 360 degree continuous rotation but with a 90 degrees active segment so needs alignment on the plenum. It is also dual output but the Rover V8 only requires one, the yellow signal wire being unused. The original carbon track TPS has spring tension forcing it against the throttle stop the HE does not but users report no problems in practice. Unfortunately the current drain of this H E TPS exceeds that of the carbon TPS so the regulated 5v supply on the TPS 3 pin socket from the ECU cannot be used and another voltage source is required. I was also hoping that the original ECU earth on the 3 pin TPS socket could conveniently be used but as this earth is shared with other sensors using it caused the coolant temperature sensor to misread. A convenient 12 volt supply is however available from the fuel injector on cylinder number 1. As this is the main 12 volt rail feeding many other components it will be unaffected by the small current the HE TPS draws (about 9mA). A convenient earth is on the Plenum via the corner Allen bolt. The 12v supply has a bullet connectors to enable quick disconnection.
Installation
I chose to reuse the original carbon TPS econseal 3 pin socket on the loom with only the signal wire being connected to the socket central green wire ( if you have an earlier car with the RISTS 3 pin round socket it would be the red wire) so that the original carbon track TPS can always be plugged back in if necessary as a working spare. A capacitor is required between the signal output and earth to maintain the signal output during cranking so this needs to be mounted securely. A small plastic box with an internal tag block is a convenient and neat way to keep things tidy. Offer the HE TPS to the plenum, the brass shaft locates in the throttle slot, this may take a bit of patience and will be correct when the aluminium plate is flush with the plenum face. Connect the signal output to the original TPS socket and check that the new 12v supply, the capacitor and new earth are correctly wired. Turn the ignition On but do not start the engine. Measure the voltage between earth and the white TPS signal wire it should track from around 0.3 volt at idle to about 4.95volts for a fully open throttle.You may need to rotate the TPS to achieve these figures. If the volts are reversed i.e. from 4.95 at idle etc. the TPS will need taking off the aluminium plate and turning through 180 degrees. As a final set up carefully rotate the TPS until about 0.34volts is seen in the idle position, this may be verified on Rovergauge as 5-7% and ensures that the ECU recognises that the TPS at its minimum position is at idle otherwise if the voltage is lower the ECU may throw a fault code and adopt open loop control. The capacitor will ensure that the ECU sees the 0.34 v signal output from the TPS during cranking, its value is not critical but 220uF and 25 volt working was fine, note that the capacitor is polarity sensitive, the negative end is clearly marked and connects to earth.
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Circuit Diagram
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Many thanks to Axel Krug who developed the Hall Effect conversion and his invaluable advice and to Mark Thompson for technical help during the testing.
Suppliers
Econoseal plug/sockets: eBay
Capacitor: CPC.farnell.com
Tag strip: hificollective.co.uk
ABS Box, Kemo GO23: Farnell.com
Suppliers
Econoseal plug/sockets: eBay
Capacitor: CPC.farnell.com
Tag strip: hificollective.co.uk
ABS Box, Kemo GO23: Farnell.com