Throttle Opening-Put to bed

20Titan05 · 01-16-2006, 10:10 AM

I've seen some people post about getting 100% opening on the throttle plate. A while back, I posted this:

For Nissan, throttle position is measured in 1/8th incriments, so 80% = 8/8ths = WOT. 78% is more than likely a rounding error, so some guys might see 82%. If someone is seeing 100%, that's probably because that's the way that tool reads it.

I finally read some of the resonses and I wanted to clear this up.
Some friendly responses:

I don't think I'll listen to any of your "engineering expertise" if you think that 8/8 = 80%

Another one:

how can you possibly control proper a/f ratio with 1/8 increments on the throttle plate? Plus, imagine how your truck would feel at under normal or WOT driving with a plate that opens and closes in 1/8 increments...

Luckily, SCR38 checked and said: (thanks SCR38!!)

I connected my OBD scan tool and at full throttle opening it indicated 79.2%. It changed as the accelerator pedal was moved, but never went over the 79.2%.

Please understand, I'm not saying that the plate opens in 1/8th incriments. That would be terrible. I'm only saying that it is MEASURED in 1/8th incriments and that at 8/8ths, its WOT. For some reason, many tools indicate "%" as the measurement unit which causes alot of confusion. It should say 80/80 at WOT or something like that.

So without any mods, you're getting 100% throttle opening. If a "black box" claims to give you 100% throttle opening, then at best, they're just changing the way its measured/indicated on the tool.

scr38 · 01-16-2006, 11:37 AM

I do not agree that the throttle opening is measured in 1/8 increments. I did check what the OBD readout software reads while the throttle is opened. There is a way to see the throttle plate open. With the key on, but with the engine NOT running put the shift selector in D. Remove the intake tube at the throttle body so you can see the throttle plate. Have someone press the throttle slowly to the full open and closed position several times. You will see the throttle plate move smoothly from the closed position to full open. The readout on my software shows 79.2 % open when the throttle plate is full open, and reads out smoothly from 0 to 79.2% and back to zero. It is not reading out in 1/8 increments, but in .01% increments. The actual throttle position sensors have a analog output, between .36 volts and 4.75 volts.
I don't know why the OBD software reads out only 79.2% when the throttle plate is fully open. It could be due to the fact that Nissan does not refer to throttle opening in %, but in degrees.
When I make acceleration test runs and check the OBD readout I see that the throttle goes to full opening, and stays there until I let off the accelerator. It does not cut back the opening after reaching a specific RPM as some have suggested.
Bottom line - MY throttle plate is going full open when I push the pedal down, and stays there until I let off. The fact that my software says that it is 79.2% open isn't a big concern to me.

*TitanFan59* · 01-16-2006, 12:07 PM

This is one of those I say tomato you say toma to things. We all win.

20Titan05 · 01-16-2006, 01:16 PM

TitanFan,
You're so right!

SCR38, you're right too, and I thank you! I'm not sure how else to say that the throttle is measured in 8ths, but can be adjusted and indicated by a measuring tool in any incriments, as you said. The only reason I say anything about the "8ths" is to make sense of the fact that 80% (which should say 80/80) is actually WOT. You know that and have proved it.

Enough said. As long as nobody's looking for 100% throttle opening anymore, then we all win.

Armada · 01-16-2006, 03:11 PM

Now that everybody is right, one simple question: Regardless of what the instruments say and how you interpret them, does the dang throttle open all the way with the petal to the floor? Yes or No, please. Scr38 says yes. Is that right?

scr38 · 01-17-2006, 07:53 AM

Quote:

Originally Posted by Armada

Now that everybody is right, one simple question: Regardless of what the instruments say and how you interpret them, does the dang throttle open all the way with the petal to the floor? Yes or No, please. Scr38 says yes. Is that right?

----Yes----

**loufish** · 01-19-2006, 05:50 AM

Your OBD toll, is it reading the requested throttle opening, or the actual throttle opening...?
When I had my truck dyno'ed at Stillen several months ago, he spoke to me about the difference between what the gas pedal was doing vs the actual throttle plate opening, he claims off the line the throttle does NOT open all the way when the pedal is floored(hard WOT drag style start), and he also claims during shifts the plate will close & re-open during the shift.
I'm just sharing what I was told, not stating as fact...
An OBD tool should be reading 2 parameters, requested throttle, and actual throttle...

20Titan05 · 01-20-2006, 01:41 PM

Quote:

Originally Posted by loufish

When I had my truck dyno'ed at Stillen several months ago, he spoke to me about the difference between what the gas pedal was doing vs the actual throttle plate opening, he claims off the line the throttle does NOT open all the way when the pedal is floored(hard WOT drag style start), and he also claims during shifts the plate will close & re-open during the shift.
I'm just sharing what I was told, not stating as fact...
An OBD tool should be reading 2 parameters, requested throttle, and actual throttle...

The Stillen guys are right. Since we have an electronic throttle, or "drive by wire" as some people say, at times, the pedal and throttle body opening don't match.

The drag style start delay is to prevent a jumpy start in "normal" driving because the electonic motor can open the throttle nearly instantly. I know that would be great for drag racing, but not in a parking lot at the grocery store. The delay works for all throttle openings, its just easier to see at WOT. I don't have the facts, but I would guess all manufacturers do the same thing.

At the shift, the throttle closes slightly to smooth out the shift. Again, not great for racing by good every day.

I think the WOT shifts for Titan are too soft. Anyone else agree?

Armada · 01-20-2006, 03:23 PM

That's what I was thinking too. Torque management system trying to do the thinking for us. Anyone figured out how to work around that.

I know we have the "burnout" wiring work-around posted elsewhere here, but that probably only deals with the safety issue of limiting throttle advance while braking.

**loufish** · 01-20-2006, 09:52 PM

Quote:

I think the WOT shifts for Titan are too soft. Anyone else agree?

I do! I like a little firmer shifts, not hard banging, just quick & firm.
We need a torque managment tweak, if you had a cable on the throttle it would open just as fast as the pedal was floored, but the TM programing denies us...
So we need a more aggressive timimg curve and a throttle that follows the pedal exactly...and while I'm still in the dream mode throw in a set of 4:10 rear gears!

Thrust_Titan · 01-25-2006, 04:37 AM

Quote:

Originally Posted by 20Titan05

I've seen some people post about getting 100% opening on the throttle plate. A while back, I posted this:

For Nissan, throttle position is measured in 1/8th incriments, so 80% = 8/8ths = WOT. 78% is more than likely a rounding error, so some guys might see 82%. If someone is seeing 100%, that's probably because that's the way that tool reads it.

I finally read some of the resonses and I wanted to clear this up.
Some friendly responses:

I don't think I'll listen to any of your "engineering expertise" if you think that 8/8 = 80%

Another one:

how can you possibly control proper a/f ratio with 1/8 increments on the throttle plate? Plus, imagine how your truck would feel at under normal or WOT driving with a plate that opens and closes in 1/8 increments...

Luckily, SCR38 checked and said: (thanks SCR38!!)

I connected my OBD scan tool and at full throttle opening it indicated 79.2%. It changed as the accelerator pedal was moved, but never went over the 79.2%.

Please understand, I'm not saying that the plate opens in 1/8th incriments. That would be terrible. I'm only saying that it is MEASURED in 1/8th incriments and that at 8/8ths, its WOT. For some reason, many tools indicate "%" as the measurement unit which causes alot of confusion. It should say 80/80 at WOT or something like that.

So without any mods, you're getting 100% throttle opening. If a "black box" claims to give you 100% throttle opening, then at best, they're just changing the way its measured/indicated on the tool.

DTC P1705 THROTTLE POSITION SENSOR

Description

Electric throttle control actuator consists of throttle control motor, accelerator pedal position sensor, throttle position sensor, etc. The actuator sends a signal to the ECM, and ECM sends signals to TCM with CAN communication.

CONSULT-II Reference Value

Item name: Condition: Display value (Approx.)

ACCELE POSI Released accelerator pedal. 0.0/8

Fully depressed accelerator pedal. 8/8

THROTTLE POSI Released accelerator pedal. 0.0/8

Fully depressed accelerator pedal. 8/8

On Board Diagnosis Logic

This is not an OBD-II self-diagnostic item.
Diagnostic trouble code “P1705 TP SEN/CIRC A/T” with CONSULT-II is detected when TCM does not receive the proper accelerator pedal position signals (input by CAN communication) from ECM.

Possible Cause

Harness or connectors
(The sensor circuit is open or shorted.)

DTC Confirmation Procedure

NOTE:

If “DTC Confirmation Procedure” has been previously performed, always turn ignition switch “OFF” and wait at least 10 seconds before performing the next test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.

WITH CONSULT-II

1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “DATA MONITOR” mode for “A/T” with CONSULT-II.
3. Start engine and let it idle for 1 second.
4. If DTC is detected, go to AT-125, "Diagnostic Procedure" .

helomech · 01-25-2006, 07:27 AM

Quote:

Originally Posted by Armada

That's what I was thinking too. Torque management system trying to do the thinking for us. Anyone figured out how to work around that.

I know we have the "burnout" wiring work-around posted elsewhere here, but that probably only deals with the safety issue of limiting throttle advance while braking.

I read something about not being able to burnout with the break pedal held down. My truck will smoke the tires while holding down the break pedal is there something wrong?

**loufish** · 01-25-2006, 04:31 PM

Quote:

I read something about not being able to burnout with the break pedal held down. My truck will smoke the tires while holding down the break pedal is there something wrong?

Mine does NOT...I disconnected one of my brake switch wires, and gave it a try....here comes the smoke!
I don't know why it seems some trucks have this issue and others do not...sorry

helomech · 01-25-2006, 09:17 PM

Quote:

Originally Posted by loufish

Mine does NOT...I disconnected one of my brake switch wires, and gave it a try....here comes the smoke!
I don't know why it seems some trucks have this issue and others do not...sorry

Thanks the first time I read about this I ran outside and tried it and I could smoke the tires for as long as I want. My only concern is that this is supposed to be a safety feature in case the throttle sticks.

20Titan05 · 01-26-2006, 02:31 PM

Quote:

Originally Posted by Thrust_Titan

DTC P1705 THROTTLE POSITION SENSOR

Description

Electric throttle control actuator consists of throttle control motor, accelerator pedal position sensor, throttle position sensor, etc. The actuator sends a signal to the ECM, and ECM sends signals to TCM with CAN communication.

CONSULT-II Reference Value

Item name: Condition: Display value (Approx.)

ACCELE POSI Released accelerator pedal. 0.0/8

Fully depressed accelerator pedal. 8/8

THROTTLE POSI Released accelerator pedal. 0.0/8

Fully depressed accelerator pedal. 8/8

.

You're the man! Thanks for that detail.