Viable Option for TPS Replacement

[Tom]

There's an option for an adapter:

"This kit only works for 944 and 944 Turbo with modification to the drive adapter for the TPS shaft. Charge is $20 for modification"

Very confusing

But then it says nothing about the electrical connector, which clearly isn't the same as the factory connector. You might call them, but I'd be surprised if it could be used plug n play with a factory DME.

[cda951]

There's an option for an adapter:

"This kit only works for 944 and 944 Turbo with modification to the drive adapter for the TPS shaft. Charge is $20 for modification"

Very confusing

But then it says nothing about the electrical connector, which clearly isn't the same as the factory connector. You might call them, but I'd be surprised if it could be used plug n play with a factory DME.

That's 100% only for use with aftermarket EFI. Zooming out from the carbon track vs Hall sensor arrangement, the 944/951 DME needs a physical "on" or "off" signal from the TPS microswitch to enable idle control or fuel cut during closed-throttle deceleration. The next generation of Bosch and other DME/ECU control software (early 1990s) would recognize/flag 0% throttle via the TPS as "idle," hence the three wire connector versus five for the 951.

I have been pedantic in the past on this forum and others: a throttle position sensor as used in the 951 and many later engines has a potentiometer to measure throttle angle (but the 951 version is unique in having a separate microswitch). A throttle switch as used in the NA 944 contains only two microswitches, one for idle, and one for full load (more than 2/3 throttle angle).

I have the VEMS "plug and play" system for my 951, still has a good stock TPS and wiring---the microswitch is not used, it flags 0% as idle. If I ever give up on the pipe dream of a 07K engine swap, I will go with a full custom harness which includes an adapter bracket and connector for a more modern 3-wire BMW E36 TPS.

[zooklm1]

I looked up a 1998 Volvo V70 and it still has a TPS listed under Fuel stuff. I believe the V70 went to an electronic throttle actuator in 1999 or 2000. However the Volvo TPS has a 3 prong plug. Here is a link at rockauto
https://www.rockauto.com/en/catalog/vol ... (tps),5136

I hope this helps

[Tom]

There's an option for an adapter:

"This kit only works for 944 and 944 Turbo with modification to the drive adapter for the TPS shaft. Charge is $20 for modification"

Very confusing

But then it says nothing about the electrical connector, which clearly isn't the same as the factory connector. You might call them, but I'd be surprised if it could be used plug n play with a factory DME.

That's 100% only for use with aftermarket EFI. Zooming out from the carbon track vs Hall sensor arrangement, the 944/951 DME needs a physical "on" or "off" signal from the TPS microswitch to enable idle control or fuel cut during closed-throttle deceleration. The next generation of Bosch and other DME/ECU control software (early 1990s) would recognize/flag 0% throttle via the TPS as "idle," hence the three wire connector versus five for the 951.

I have been pedantic in the past on this forum and others: a throttle position sensor as used in the 951 and many later engines has a potentiometer to measure throttle angle (but the 951 version is unique in having a separate microswitch). A throttle switch as used in the NA 944 contains only two microswitches, one for idle, and one for full load (more than 2/3 throttle angle).

I have the VEMS "plug and play" system for my 951, still has a good stock TPS and wiring---the microswitch is not used, it flags 0% as idle. If I ever give up on the pipe dream of a 07K engine swap, I will go with a full custom harness which includes an adapter bracket and connector for a more modern 3-wire BMW TPS.

If the factory TPS harness wires supplied enough power, I'd see about using just a Hall sensor and a little circuit to simulate the closed switch when then the sensor is in the idle zone... But I'm 96.7% sure it only has high impedance inputs without any real current to drive something like that....

[Cruise98]

I have a dead TPS and can send it to you if it would be any help. Porsche has them listed for a bargain price of $700!

I tried a Bosch but it was dead out of the box.

[johnb]

But then it says nothing about the electrical connector, which clearly isn't the same as the factory connector. You might call them, but I'd be surprised if it could be used plug n play with a factory DME.

That's 100% only for use with aftermarket EFI. Zooming out from the carbon track vs Hall sensor arrangement, the 944/951 DME needs a physical "on" or "off" signal from the TPS microswitch to enable idle control or fuel cut during closed-throttle deceleration. The next generation of Bosch and other DME/ECU control software (early 1990s) would recognize/flag 0% throttle via the TPS as "idle," hence the three wire connector versus five for the 951.

I have been pedantic in the past on this forum and others: a throttle position sensor as used in the 951 and many later engines has a potentiometer to measure throttle angle (but the 951 version is unique in having a separate microswitch). A throttle switch as used in the NA 944 contains only two microswitches, one for idle, and one for full load (more than 2/3 throttle angle).

I have the VEMS "plug and play" system for my 951, still has a good stock TPS and wiring---the microswitch is not used, it flags 0% as idle. If I ever give up on the pipe dream of a 07K engine swap, I will go with a full custom harness which includes an adapter bracket and connector for a more modern 3-wire BMW TPS.

If the factory TPS harness wires supplied enough power, I'd see about using just a Hall sensor and a little circuit to simulate the closed switch when then the sensor is in the idle zone... But I'm 96.7% sure it only has high impedance inputs without any real current to drive something like that....

For what they cost, a solution that requires a power feed from somewhere else is probably worth it.

[Tom]

That's 100% only for use with aftermarket EFI. Zooming out from the carbon track vs Hall sensor arrangement, the 944/951 DME needs a physical "on" or "off" signal from the TPS microswitch to enable idle control or fuel cut during closed-throttle deceleration. The next generation of Bosch and other DME/ECU control software (early 1990s) would recognize/flag 0% throttle via the TPS as "idle," hence the three wire connector versus five for the 951.

I have been pedantic in the past on this forum and others: a throttle position sensor as used in the 951 and many later engines has a potentiometer to measure throttle angle (but the 951 version is unique in having a separate microswitch). A throttle switch as used in the NA 944 contains only two microswitches, one for idle, and one for full load (more than 2/3 throttle angle).

I have the VEMS "plug and play" system for my 951, still has a good stock TPS and wiring---the microswitch is not used, it flags 0% as idle. If I ever give up on the pipe dream of a 07K engine swap, I will go with a full custom harness which includes an adapter bracket and connector for a more modern 3-wire BMW TPS.

If the factory TPS harness wires supplied enough power, I'd see about using just a Hall sensor and a little circuit to simulate the closed switch when then the sensor is in the idle zone... But I'm 96.7% sure it only has high impedance inputs without any real current to drive something like that....

For what they cost, a solution that requires a power feed from somewhere else is probably worth it.

I actually just got a candidate potentiometer today and will see about adapting it to the shaft in the next few days. The microswitch should be easy enough. The biggest challenge really is going to be integrating the 6-pin junior timer connector. Ideally, I'd mold it into the case, but the fall back is to have a cable coming out of it that plugs into the factory connector. So many projects, so little time. I love being 'retired.'

[danmartinic]

Off topic but I just discovered that brand new AFMs are now available.. for about $300

For those of us keeping mostly stock... um.. should we not get one while we can??

[Latitude48]

Off topic but I just discovered that brand new AFMs are now available.. for about $300

For those of us keeping mostly stock... um.. should we not get one while we can??

I don't know where you can find one that cheap as both the normal 944 and the 951 rebuilt models are close to $900 each from Porsche.

Personally, I'd put the money towards a MAF system such as the Storch VE.

[danmartinic]

https://944online.com/air-flow-meter-944-turbo/

https://www.europaparts.com/mass-air-fl ... 24C8nIBHq9

https://www.pelicanparts.com/More_Info/ ... yPassCat=Y