TP and WOT

[malave7567]

Originally Posted by Shutter

this just confirms my undying hatred for DBW

Coming from an LS3... the throttle plate never read 100% open, it's max was also somewhere in 80-90% I think. Another drive-by-wire vehicle.

Makes me sometimes miss my carb'ed Toyota 3TC engine lol

[continuecrushing]

It just sucks that you tell the car to do one thing(simple things, like, not have crappy throttle response haha) and it takes your input into consideration but then does whatever the hell it feels like. Step on the gas pedal 50% while on the freeway? You must want WOT! WEEEEEEE!!!

Clutch and gas pedal are by far my biggest complaints(only really) of this vehicle

[glamcem]

I think this explains the weird pedal feel that I have been having for a while, when stepped on the gas (WOT) car feels like it doesn't want to move as opposed to partial throttle and gradually increasing the speed..

As I understand this is not something that can be fixed with tune

Any update/ remedy on this issue? or we simply need to live with this ?

:/

[roddy]

I miss throttle cables.

[Kodename47]

Originally Posted by glamcem

I think this explains the weird pedal feel that I have been having for a while, when stepped on the gas (WOT) car feels like it doesn't want to move as opposed to partial throttle and gradually increasing the speed..

As I understand this is not something that can be fixed with tune

Any update/ remedy on this issue? or we simply need to live with this ?

:/

I'm not sure this thread has really revealed any issues. Just because the different logging software don't show 100% on the TPS doesn't mean that the throttle isn't at maximum opening.

What you're actually describing when you stamp on the pedal could be transient retard at work and/or the transition into OL isn't smooth. Any of that can be fixed by a tune.

Alternatively if you think the throttle response is rubbish, go have a play with the throttle tables.

[glamcem]

Originally Posted by Kodename47

I'm not sure this thread has really revealed any issues. Just because the different logging software don't show 100% on the TPS doesn't mean that the throttle isn't at maximum opening.

What you're actually describing when you stamp on the pedal could be transient retard at work and/or the transition into OL isn't smooth. Any of that can be fixed by a tune.

Alternatively if you think the throttle response is rubbish, go have a play with the throttle tables.

I understand the differences between various logging softwares but the difference between WOT and partial throttle is pretty obvious ..throttle cannot be 100% for sure..
and it seems like it's not something that can be fixed easily with tune otherwise there would be a fix for that..

[Kodename47]

Originally Posted by glamcem

I understand the differences between various logging softwares but the difference between WOT and partial throttle is pretty obvious ..throttle cannot be 100% for sure..
and it seems like it's not something that can be fixed easily with tune otherwise there would be a fix for that..

So you've actually measured the throttle plate opening? If not, how are you sure? I'm also not sure of the symptoms you're on about, but I bet it has nothing to do with throttle angles. Best bet, log it and post it and it may give you a clue as to what's actually happening rather than random speculation.

[glamcem]

Originally Posted by Kodename47

So you've actually measured the throttle plate opening? If not, how are you sure? I'm also not sure of the symptoms you're on about, but I bet it has nothing to do with throttle angles. Best bet, log it and post it and it may give you a clue as to what's actually happening rather than random speculation.

I never looked at the throttle angles and am not sure how someone can measure the throttle plate opening..with that said, I took some logs and saw the throttle position on WOT has never been over 82% ..it is pretty noticeable when on WOT so I am not dreaming I thought I had some heat soak issues at track since that's where I spend most of my time on WOT, for street driving though car always feels faster (partial throttle ).

I will take a few more logs with partial throttle but I am willing to bet you it will be different

[Kodename47]

Originally Posted by glamcem

I never looked at the throttle angles and am not sure how someone can measure the throttle plate opening..with that said, I took some logs and saw the throttle position on WOT has never been over 82% ..it is pretty noticeable when on WOT so I am not dreaming I thought I had some heat soak issues at track since that's where I spend most of my time on WOT, for street driving though car always feels faster (partial throttle ).

I will take a few more logs with partial throttle but I am willing to bet you it will be different

I don't understand:
A) What issue you're encountering
and
B) Why you think partial accerator pedal will give you a larger throttle opening?

Unless of course the mapping has been adversely changed? Which tuning platform are you on?

[glamcem]

Originally Posted by Kodename47

I don't understand:
A) What issue you're encountering
and
B) Why you think partial accerator pedal will give you a larger throttle opening?

Unless of course the mapping has been adversely changed? Which tuning platform are you on?

Did you read all the posts in this thread? I'm experiencing the same exact issue what everybody does here..

Sluggishness on WOT,

2) And because car feels very weak and something is limiting the power.. It's been discussed here and also few other threads..

If you're not FI it may be harder to notice since all things combined (parasitic loss/load etc) it's a lot more apparent on a more powerful car.

[arghx7]

A throttle (which is a butterfly valve) is a non-linear device. Those who think that somehow they were linear on cable throttled engines are remembering with rose-colored glasses.

So here's the opening area of the valve vs airflow rate through the throttlebody relationship. Notice how it's totally non-linear? It's more like logarithmic. Once you're at about 50% opening area the throttle barely restricts the airflow.



Now in the image on the right below, you can see throttle rotation degrees vs opening area relationship... totally nonlinear. On the left you can see that at WOT (pressure ratio = 1), air flow is moving at its normal rate as the engine draws it in (on an n/a engine) or a turbo pushes it in. As the throttle closes it speeds up until you reach the flat area, the sonic area, where air velocity is steady. This is why a throttle valve and an accelerator pedal need to behave differently at small opening angles.

It worked the same way with cable throttles, except you were stuck with whatever linkage design the throttlebody came with. You could also feel in the gas pedal when crap had built up in the throttlebody, and you had idle air control solenoids, fast idle valves, and other parts that could break down as the engine aged.

As for the 80% vs 100% reading from your various tools:

It's a 0-5 volt sensor. If the reading is based on actual voltage vs max voltage, it will never hit 100%. Why? If it hit 100%, as in 5 volts, it would indicate an electrical fault. The upper and lower bounds of the voltage range are for basic diagnostic checks (open or short circuit) and are ignored. That's why there are PIDs for relative throttle angle.

[Kodename47]

Originally Posted by glamcem

Sluggishness on WOT,

2) And because car feels very weak and something is limiting the power.. It's been discussed here and also few other threads..

If you're not FI it may be harder to notice since all things combined (parasitic loss/load etc) it's a lot more apparent on a more powerful car.

TBH, most of this thread is about understanding the logged TPS output and not much else, I don't see any other real issues.

I am FI and I definitely don't have the issue you're on about. My TB shows maximum opening all the way to redline.

So, either your DWB tables have been made incorrect or potentially you have another issue causing the car to run poorly on WOT. It could be a multitude of factors but I can't forsee it actually being throttle body related, unless you have a faulty TB.

[glamcem]

Originally Posted by Kodename47

TBH, most of this thread is about understanding the logged TPS output and not much else, I don't see any other real issues.

I am FI and I definitely don't have the issue you're on about. My TB shows maximum opening all the way to redline.

So, either your DWB tables have been made incorrect or potentially you have another issue causing the car to run poorly on WOT. It could be a multitude of factors but I can't forsee it actually being throttle body related, unless you have a faulty TB.

OP

I've noticed in a lot of logs that at WOT the TB is actually closing up to about 10% as the revs climb. Is this the ECU trying to limit power/load, or is that actually the optimal opening?

I would think that fully open would always be the best for power?

Here's one log that shows it clearly:

http://www.datazap.me/u/wparsons/mar...log=0&data=1-2

and another

Mine appears to do the same. Here is a look at my most recent log: http://www.datazap.me/u/luckrider/e8...zoom=2863-3245

I did realize that I am not pushing the throttle 100% though. I used to bury it into the floor and I noticed that full throttle is not as WOT as buried in the floor WOT. Here is an old log that goes over 100%

that is exactly what I am seeing when on WOT so I don't think I am the only one who is experiencing it. the thing is, WOT delay was noticeable on the stock cars that I test drove before I made my purchase, my wife's Outback also had the similar feel on WOT but I think that's due to Torque management..I thought after the tune it would go away but it didn't

[Kodename47]

Originally Posted by glamcem

That is exactly what I am seeing when on WOT so I don't think I am the only one who is experiencing it. the thing is, WOT delay was noticeable on the stock cars that I test drove before I made my purchase, my wife's Outback also had the similar feel on WOT but I think that's due to Torque management..I thought after the tune it would go away but it didn't

We've already cleared up what happens in logs should have no detriment on what's happening while on WOT. That's understanding the TPS and logs, which is what I said.


As for a delay on WOT, do you mean when stamping on the accelerator pedal? That really has little to do with the throttle opening and more to do with other maps, not surprisingly usually transient maps. What makes you think that the tune isn't to blame?


But believe what you will, clearly you're determined that the throttle is at fault for all of this so I'll now let you get on with that....