Tps voltage

[Colorobo]

If the tps voltage is higher is there more fuel or less. I am still running lean closed air screws and that helped. had them open 1/2 a turn and had a pop cough of idle. Thanks RP

[docc]

So . . . good question and worth working through. Moved this topic to Technical Topics . . .

Stand by. Pretty sure good answers will flow from your good question.

[docc]

Short answer is: no, you cannot add or subtract fuel simply by rotating the TPS.  While this was once thought, it turns out the TPS baseline is entirely about indexing the ECU "map" to the throttle body openings. Best to index it accurately.  Take a look at the "Decent Tune-up" procedure. It is a great starting point.

 

[Lucky Phil]

6 minutes ago, docc said:

So . . . good question and worth working through. Moved this topic to Technical Topics . . .

Stand by. Pretty sure good answers will flow from your good question.

Higher the voltage the more fuel.

Ciao

[Lucky Phil]

3 minutes ago, docc said:

Short answer is: no, you cannot add or subtract fuel simply by rotating the TPS.  While this was once thought, it turns out the TPS baseline is entirely about indexing the ECU "map" to the throttle body openings. Best to index it accurately.  Take a look at the "Decent Tune-up" procedure. It is a great starting point.

 

Ok docc, I will be happy to stand corrected here but if you move the TPS to a higher voltage output for the same throttle plate position wont that be telling the ecu that the throttle is open a greater amount than it actually is and "by and large" give longer injector duration for a given rpm because it thinks the throttle is actually open more than it is?

Thats always been my understanding, I might be wrong. You set the base TPS voltage with the throttle plates closed to give the ecu the shut limit and then it calculates throttle plate position from there. If say you have the plates closed but set the TPS voltage at 3 deg open the ecu will supply fuel or injector pulse width advanced 3 degrees across the board which would generally mean more fuel. I may have missed something here, others may know the details better.

Ciao

[docc]

2 minutes ago, Lucky Phil said:

Ok docc, I will be happy to stand corrected here but if you move the TPS to a higher voltage output for the same throttle plate position wont that be telling the ecu that the throttle is open a greater amount than it actually is and "by and large" give longer injector duration for a given rpm because it thinks the throttle is actually open more than it is?

Thats always been my understanding, I might be wrong. You set the base TPS voltage with the throttle plates closed to give the ecu the shut limit and then it calculates throttle plate position from there. If say you have the plates closed but set the TPS voltage at 3 deg open the ecu will supply fuel or injector pulse width advanced 3 degrees across the board which would generally mean more fuel. I may have missed something here, others may know the details better.

Ciao

I always thought that, too.  And even tried to "add fuel" that way on the idea that the motor must be "lean."  Just turns out more complex than that because of the "mapping."

@Meinolf understands this better than anyone I know. 

[Lucky Phil]

11 minutes ago, docc said:

I always thought that, too.  And even tried to "add fuel" that way on the idea that the motor must be "lean."  Just turns out more complex than that because of the "mapping."

@Meinolf understands this better than anyone I know. 

Hopefully he'll chime in.

Thinking about it docc the "overall richening" issue not being valid will be because at some points in the map and engine operating envelope the fuel pulse width and therefor delivery will actually be reduced at least not increased due to volumetric efficiency considerations at different rpm and load points. 

Ciao

[docc]

16 minutes ago, Lucky Phil said:

Hopefully he'll chime in.

Thinking about it docc the "overall richening" issue not being valid will be because at some points in the map and engine operating envelope the fuel pulse width and therefor delivery will actually be reduced at least not increased due to volumetric efficiency considerations at different rpm and load points. 

Ciao

Yessir. That is what I gathered from it being more than just linear.

Like when I just put bigger jets in my Holley spreadbore . . .

[MartyNZ]

1 hour ago, Colorobo said:

If the tps voltage is higher is there more fuel or less. I am still running lean closed air screws and that helped. had them open 1/2 a turn and had a pop cough of idle. Thanks RP

TPS voltage affects more than just injection duration. Injection and ignition timing are also affected.  See https://www.v11lemans.com/forums/index.php?/topic/17865-v11-ecu-diagnostics-and-reprogramming/&do=findComment&comment=207884

The engine is transformed from smooth & sweet to brutally rough if you set the TPS wrong. Try it, but be ready on the kill switch. 

[Lucky Phil]

19 minutes ago, docc said:

Yessir. That is what I gathered from it being more than just linear.

Like when I just put bigger jets in my Holley spreadbore . . .

My friend at one point was modifying Harley pressure regs to be adjustable ( same ones as our bike runs) so you could easily richen the whole map. He accepted it was a band aid because he knows a lot about efi stuff but it was "good enough" for the Harley guys and actually solved the running issues they had at the time. I spent some time assembling them and setting them on the test rig.

Ciao

[Lucky Phil]

1 minute ago, MartyNZ said:

TPS voltage affects more than just injection duration. Injection and ignition timing are also affected.  See https://www.v11lemans.com/forums/index.php?/topic/17865-v11-ecu-diagnostics-and-reprogramming/&do=findComment&comment=207884

 

The engine is transformed from smooth & sweet to brutally rough if you set the TPS wrong. Try it, but be ready on the kill switch. 

Yes of course, a good refresher. Thanks

Ciao

[docc]

Best I can gather from all the respectable contributors is that if you really want that much more out of a V11,  take off the license plate and back it up to a Roller 8 Valve.

Just be willing to give up your quickie RedFrame, if ya gots one. 

Otherwise, the V11 can really be tuned very finely, of you are wiling to take the time and trouble.