Throttle Position Sensor Adjustment-and the reasons why!

[Frostbite]

This is a post I had hoped Supertuner would make. Since he didn't I felt compelled to ask this question. I adjusted mine from .75 to 1.0. (not the 1.07) Perhaps I should have moved it even further? Is the reading at WOT more important than the reading at idle? I also see several guys have measured their TSP setting at idle. Should it be done at idle or just with the key turned on as I did?
Is adjusting the TPS like adjusting the timing on a car where you turn the distributor to advance the timing until you hear audible pinging and then back it off a hair? I also notice when I do this on a car or truck that my economy improves right along with the drivability and power.
Am I comparing apples to oranges here or does the TPS (at least in laymans terms) function similar to a distributor? I understand that the TPS sends signals to the ECU(?) and through the digital engine management somehow adjusts the timing of the flame front and from this point on I could use some schooling. Thanks. PB

 

[welterracer]

A TPS is not a distributer.... But it is related to the function of timing controled by the ECM...


WHen you give your sled gas at the throttle the ecm reads the voltage and then adjusts timing to give the best performace..

Too high of a reading can cause alot of problems but i noticed on mine that you cannnot adjust it that far to get it out of control..

There is very litte adjustment !!

 

[race24x]

I was a GM tech for 8 years I understand the basics for TPS but arent there other sensors that contibute to timing of the engine. On a car there are knock sensors air flow sensors o2 sensors etc that all send data for the ECU to make decisions. Do we have these sensors as well or is it a basic system of x amount of throttle means x amount of timing advance retard?

 

[SUPERTUNER]

This is a post I had hoped Supertuner would make. Since he didn't I felt compelled to ask this question. I adjusted mine from .75 to 1.0. (not the 1.07) Perhaps I should have moved it even further? Is the reading at WOT more important than the reading at idle? I also see several guys have measured their TSP setting at idle. Should it be done at idle or just with the key turned on as I did?
Is adjusting the TPS like adjusting the timing on a car where you turn the distributor to advance the timing until you hear audible pinging and then back it off a hair? I also notice when I do this on a car or truck that my economy improves right along with the drivability and power.
Am I comparing apples to oranges here or does the TPS (at least in laymans terms) function similar to a distributor? I understand that the TPS sends signals to the ECU(?) and through the digital engine management somehow adjusts the timing of the flame front and from this point on I could use some schooling. Thanks. PB

PB...I don't always have the chance to check the message boards as much as some of you would like me too but you are always welcome to e-mail me with any questions or call. KliesECP@aol.com (203)756-7019 M-F 9AM 6PM. Sorry but I am a busy man. I try to help as much as I could.

To answer your questions...Setting the TPS (not TSP) to 1.0 at idle will suffice. The range of movement on volts is going to be the same regardless because the throttle lever range of movement doesn't change when adjusting the TPS. You do indeed adjust the TPS with the engine shut off, key in the on position, kill switch on and the throttle shut. What it does is influence the TPS to begin the timing advance earlier thereby putting heat in your combustion chamber sooner during an acceleration run. It is not a real drastic move and even with the TPS banged up as far as it will go shouldn't cause any poor running characteristics as I believe Yamaha didn't give it enough range of adjustment to allow self termination of the engine. I don't like your analogy to comparing it to a distributor. Just try setting it the way that I describe and you will be okay.

Freddie

 

[lakercr]

Freddie - any concern with doing this to a turbo RX running 6-8lbs boost with a thicker head gasket? If it shifts the power curve left I don't see a problem, as I'm still spooling up and not yet at max. boost. Wouldn't mind your opinion though...

 

[kawman]

to change timing you need to get the adjustable cam sprockets atleast that is the best way but not the only way

 

[Frostbite]

Supertuner, I appreciate the fact that I over simplified this system so more people (including myself) could understand a little more what we are actually doing in adjusting the TPS. I appreciate you taking the time to respond.
Now my only question is: Is more voltage better since there is very little adjustment and we simply can not adjust this component into the engine self destruct window? I'm sure I saw 1.24 on my meter before I retarded it back to 1.0. Thanks for all your responses. I just like to have a good rationalization for doing what we're doing. PB

 

[POWERHAULIC]

kawman, you are referring to cam timing, this discussion centers around ignition timing. These two are related, but not the same.

 

[MR.HAPPY]

Should you definitely use 10 range plugs after doing this?

BR

 

[lakercr]

If I understand Supertuner's explanation correctly, all you are doing is shifting the power curve (picture a graph) over to the left by about 600 rpm. You aren't making any more power, you're just getting it sooner in the rpm band. I doubt this adjustment would require any other changes.

 

[LazyBastard]

I was a GM tech for 8 years I understand the basics for TPS but arent there other sensors that contibute to timing of the engine. On a car there are knock sensors air flow sensors o2 sensors etc that all send data for the ECU to make decisions. Do we have these sensors as well or is it a basic system of x amount of throttle means x amount of timing advance retard?

Knock sensor is the same as for the DCS on SRX02/Viper04/Venture04. If knock is detected, it WAAAAY retards the timing.

O2 sensor is for fuel injection - if high O2, increase fuel. If low O2, decrease fuel.


Ignition timing on RX1 is controlled by a number of inputs;
RPM,
TPS,
Temperature.


Please note that RX1 is NOT equipped with DCS, so if you overadvance the timing, it CAN blow the motor. Also, just because it doesn't IMMEDIATLY self-destruct doesn't mean that it won't shorten the life.

 

[Ted Jannetty]

Here is my 2 cents, since this was my idea.
Last year I had heard grumblings about TPS being out of adjustment and causing poor fuel mileage, so while we were on the dyno I asked for a Digital Volt meter and proceeded to check the TPS voltage at idle and full throttle, I found it at .703 volts at idle and 3.4 volts at WOT.
Every 5 volt referenced system I have ever delt with always specs out at .9 Plus or Minus .1 ( .80-1.0 ) and 4.0 to 4.5 volts at WOT, with the exception of very early GM cars that used .5 to .6. These early GM also needed to see 4.0 -4.5 volts at WOT.
I had a feeling this would change the timing curve, good or bad I did not know, so I moved the TPS to 1.07 for no other reason except that that is far as it would go at current Idle speed setting.
( Keep in mind that you should set your idle speed before setting TPS as they are related)
We then made a pull and saw substantial gains from 4,000-7,000 rpm where you spend most of your time cruising on the trails, with almost no difference from 7,000 to 10,000

You can expect maybe a better holeshot with low engagement, better throttle response at trail speeds and possibly better fuel mileage, probably nothing on top end as you are out of the range where it made a difference.

Only futher testing out on the trail with careful record keeping will tell for sure wether or not this really has any effect on any of the above.

Lets keep this open and try and keep careful records so we have good information to verify good or bad.

 

[SUPERTUNER]

Freddie - any concern with doing this to a turbo RX running 6-8lbs boost with a thicker head gasket? If it shifts the power curve left I don't see a problem, as I'm still spooling up and not yet at max. boost. Wouldn't mind your opinion though...

I would not recommend that you advance timing in any manner with a turbocharged vehicle. In fact to run increased boost levels, it is desireable to retard timing thereby curbing detonation that will increase with boost.

Of course, all this is relative to what kind of combustion chamber heat is being generated in the first place. Advancing timing on an already too cool CC will make more power as long as it doesn't overheat the CC but it is risky if you ever want to make more boost.