Achenar

So I've been playing around with my Auterra diagnostic tool a bit.
I've noticed some interesting things regarding absolute throttle position.

Since I purchased my B16 swap, I knew that the TPS sensor was cocked off to one side (not centered), and probably needed adjustment.

In this position, I noticed that with my foot off the throttle, I was registering 5.7% throttle, and at WOT I was getting only 87.5% throttle according to the scan tool.

So I adjusted the TPS sensor to either extreme.

Cocked all the way clockwise, I got an off-throttle reading of 3%, and WOT @ 84%
In the other extreme, I got an off-throttle reading of 15%, and WOT @ 97.8%.

At all of the above positions, I got exactly the same idle, ~700, jumping to 850 when the radiator kicks in.

So, where do I leave the TPS sensor? It seems to me that It'd be most beneficial to get as close to 100% at WOT as possible, no? Is there any downside to having it register such a high throttle reading when idling?



-a

TurboEM1

iTrader: (1)

very interesting sorry i cant help but ill give you a bump because i would like to see an answer.

Also what tool are you using exactly to get this data? Thanks

Achenar

I must admit that my idle this morning was much higher than it was last night. I left the TPS cocked to one extreme (the one that reads 15-97% on my scan tool), and my idle was up to 1800RPM this morning. I wonder why it wasn't that high last night?

Anyways, the Auterra scan tool ( http://www.auterraweb.com/ ) is a device that plugs into the OBD2 port, and goes to a PalmOS compatible handheld. It gives live read-outs of all sensors, trouble codes, measures HP, TQ, quarter mile, and does data logging.

I've since done some more searching and googling about the TPS sensor and I found the spec of setting the TPS sensor to read .5 volts at closed throttle. This makes me wonder what exactly the percentage reading for 'Absolute Throttle Position' is interpretted from on the scan tool. I'll email them and find out.

-a

EnjoyTheRideDC2

iTrader: (1)

You need sleep....Dont forget what happened the last time u were too tired and working on your car....

LOL. j/k. Lets see what Auterra has to say...

Achenar

Thanks for the support

Heheh, I'm betting my chips on the fact that Auterra is calculating % based on total voltage (out of 5 volts). Which means at closed throttle, it's going to read 10% (0.5 volts), and at WOT it should read 90% (4.5 volts).

-a

EnjoyTheRideDC2

iTrader: (1)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Achenar &raquo;</TD></TR><TR><TD CLASS="quote">Thanks for the support

Heheh, I'm betting my chips on the fact that Auterra is calculating % based on total voltage (out of 5 volts). Which means at closed throttle, it's going to read 10% (0.5 volts), and at WOT it should read 90% (4.5 volts).

-a</TD></TR></TABLE>

See, I supported you already....Had I not mentioned that possibility, you may have been fumbled all day....

Achenar

Well Auterra sure has not been much help. Here's the reply I got from them.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">The official OBD II standards defintion is:

Absolute Throttle Position - the absolute throttle position (not the
relative or learned) throttle position. Usually above 0% at idle and less
than 100% at full throttle.

http://www.auterraweb.com/supsen.html

That is the only definition we have. It is indeed normal to have higher than
0% at idle and less that 100% at full throttle.

The OBD II standards do not provide a means of reading just the voltage.


Sincerely,

Auterra Support
support@auterraweb.com
</TD></TR></TABLE>

So I replied back.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Auterra Support,

Thank you for your reply. However this does not answer my question. The OBD2 standards can define the term "Absolute Throttle Position" all it wants, but that does not change the fact that the TPS sensor sends a voltage to the ECU, which your product is somehow interpreting as "Absolute Throttle Position."

Am I to believe based on your reply that the Absolute Throttle Position is simply an arbitrary number greater than 0%, and less than 100%? If so, then my opinion is that this information is worthless.

How is the percentage interpreted? Is it a percentage of the total max voltage? If so, then this would make sense that at off-throttle (sensor sends 0.5 volts), Auterra reports 10% (of the max of 5 volts), and at wide-open-throttle (sensor sends 4.5 volts), Auterra reports 90%. However, this is simply my speculation, which I would be happy if you could confirm or deny.

Thanks,
</TD></TR></TABLE>



-a

EnjoyTheRideDC2

iTrader: (1)

and it took them how long to give you that answer?

NumbNutts I tell ya...

xEnderx

Are you reading the percantage of voltage, or the percentage of throttle opening? Some of the aftermarket scanners are a bit imprecise. Honestly if your TPS was only reading 87.5% of actual throttle opening then you might have some problems with Vtec activation....since TPS is one of the inputs to the ECU for solenoid activation.

Bottom line....everythign is workign correctly I wouldn't worry about it.

IT'S ME DAVID

iTrader: (1)

ROOROWNS

I was pretty sure the three things that were needed for Vtec Activation were;
Oil Pressure
Engine Temperature ( operating Temp)
Speed (over 20)

I Don't think A TPS signal is needed, considering Vtec will crossover no matter what Throttle position as long as you get to the crossover point.

P.S. Please someone confirm this so i am not going around spreading bum info!

Sean

Achenar

Just got another reply

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Our scan tool does not "interpret" or "measure" anything. The OBD II
standards say the ECU send a number between 0 and 100% and the scan tool
displays the value. The ECU and its software is responsible for measuring
the voltage and providing the conversion to a percent reading.

The OBD II specification do not provide any guidance on how the voltage is
converted to a percent. The automakers are responsible for converting
voltage to a percent value. Each make/model/year car can do it differently.
I don't have any of that information.

I'm sorry, you are asking a question that we would have no way of knowing
the answer. That type of information is just not made available.


Sincerely,

Auterra Support
support@auterraweb.com
</TD></TR></TABLE>

Very strange. He's claiming that the number for Absolute Throttle Position is calculated at the ECU. Is this true? If so, how is this number calculated? I wonder if I emailed Hondata if they'd have any idea, lol.

-a

Achenar

When I get home tonight, I'm going to pull out my oldschool voltage meter (lol, anyone have a good deal on a Fluke? ).

I think this is the only way I'm going to discover any correlation between the actual throttle position and the "Absolute Throttle Position" reading from the ECU.

-a

xEnderx

Ooops...yeah, you are right. Sorry man I spent the day working on CVVT systems and I guess my brain got confused. Lol!!!


Good deal on a Fluke....wish I could find one. My Blue Point is a hunk of crap.

Achenar

Okay, here comes some really geeky **** that I just dug up.

Source: http://www.arb.ca.gov/regact/obd02/attacha.doc
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">(2.2) A table, in the standardized format detailed in Attachment A of ARB Mail-Out #95-20, May 22, 1995, incorporated by reference.
(2.2.1) The table must include the following information for each monitored component or system (either computer?sensed or ?controlled) of the emission control system:
(A) corresponding fault code
(B) monitoring method or procedure for malfunction detection
(C) primary malfunction detection parameter and its type of output signal
(D) fault criteria limits used to evaluate output signal of primary parameter
(E) other monitored secondary parameters and conditions (in engineering units) necessary for malfunction detection
(F) monitoring time length and frequency of checks
(G) criteria for storing fault code
(H) criteria for illuminating malfunction indicator light
(I) criteria used for determining out of range values and input component rationality checks

(2.2.2) Wherever possible, the table shall use the following engineering units:
(A) Degrees Celsius (°C) for all temperature criteria
(B) KiloPascals (KPa) for all pressure criteria related to manifold or atmospheric pressure
(C) Grams (g) for all intake air mass criteria
(D) Pascals (Pa) for all pressure criteria related to evaporative system vapor pressure
(E) Miles per hour (mph) for all vehicle speed criteria
(F) Relative percent (%) for all relative throttle position criteria (as defined in ISO 15031-5)
(G) Voltage (V) for all absolute throttle position criteria (as defined inISO 15031-5)</TD></TR></TABLE>

Source: http://www.arb.ca.gov/msprog/o...g.doc

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
(2.2) A table, in the standardized format detailed in Attachment A of ARB Mail-Out #95-20, May 22, 1995, incorporated by reference.
(2.2.1) The table must include the following information for each monitored component or system (either computer?sensed or ?controlled) of the emission control system:
(A) corresponding fault code
(B) monitoring method or procedure for malfunction detection
(C) primary malfunction detection parameter and its type of output signal
(D) fault criteria limits used to evaluate output signal of primary parameter
(E) other monitored secondary parameters and conditions (in engineering units) necessary for malfunction detection
(F) monitoring time length and frequency of checks
(G) criteria for storing fault code
(H) criteria for illuminating malfunction indicator light
(I) criteria used for determining out of range values and input component rationality checks
(2.2.2) Wherever possible, the table shall use the following engineering units:
(A) Degrees Celsius (°C) for all temperature criteria
(B) KiloPascals (KPa) for all pressure criteria related to manifold or atmospheric pressure
(C) Grams (g) for all intake air mass criteria
(D) Pascals (Pa) for all pressure criteria related to evaporative system vapor pressure
(E) Miles per hour (mph) for all vehicle speed criteria
(F) Relative percent (%) for all relative throttle position criteria (as defined in SAE J1979)
(G) Voltage (V) for all absolute throttle position criteria (as defined in SAE J1979)
</TD></TR></TABLE>


Alright, so this doesn't tell me much, but it does tell me that Absolute Throttle Position is calculated from voltage. So what's the formula?

I tried to look up the ISO document 15031-5. I found the link here:
http://ieeexplore.ieee.org/iel...70711
However, I need to be an IEEE member to read the document

So I browsed some more and I came up with this:
http://66.102.7.104/search?q=c...hl=en

(Google cached page from some Tacoma offroad resource ... original no longer exists!)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">THROTTLE POS
- Output Voltage of Throttle Position Sensor Calcu-lated as a percentage: 0 V → 0 %, 5 V → 100 %

Throttle valve fully closed: 7 – 11 %
Throttle valve fully open: 65 – 75 %
</TD></TR></TABLE>

Bingo!
So there you have it. 0 volts = 0% throttle. 5 volts = 100% throttle



Now if I can find some more definitive sources, I'll write Auterra back to inform them what a bunch of tards they are.

-a