2GR Camry sensitive accel pedal - Page 3 - MR2 Owners Club Message Board
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post #41 of 79 (permalink) Old March 24th, 2019, 16:56
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Ok I have the MX which I believe the same as the LX but without the Ford modules. This baby gets 50 PID/sec with a CAN-bus ECU.
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post #42 of 79 (permalink) Old March 24th, 2019, 20:24
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Originally Posted by merryfrankster View Post
We do know that the MIL for these error conditions is removed in our hacked ECU's - which is a great thing because it gives us a usefully functional CEL. I don't know the mechanism of how this is done because I don't know the underlying logic so I don't know if the error condition checking and setting is deleted entirely or just the MIL setting. Beyond this, we do not know what consequences these error conditions may have for engine control. It's been theorized that without transmission input the engine defaults to a engine-stand dyno test mode that is not affected by transmission status however we also know that in our running cars the presence or absence of a speed signal from the transmission does have an effect on the throttle behavior as can the selection of N versus D for shifter status, so the question is not straightforward to answer.
I can answer this one. The ECU has a whole bunch of faults it can throw and when the conditions are met it goes to a table and if there's a code there the code is thrown according to the code's data (for example it could set a fault but not set the CEL or even make it blink). I've simply removed the undesired faults from this table so the underlying behavior is not actually different at all. Note that there a bunch of faults in this table that are set like that. the ECU can throw some faults that Toyota has disabled so disabling faults like this is intended behavior in the ECU.

now with that said, if the throttle behavior is altered because of the transmission, it might be possible to alter some of the sensor transfer curves to put the ECU in a better place. or i might be able to find the different throttle table that it is actually using and change that. even if it is in some default "no trans" behavior there's a damn good chance there's a table for that also. just to give you an idea my notes include 1557 tables and transfer curves on the rav4 tune (8 and 16 bit) and that does not include all the scalars since those aren't marked. some of this is a bit like hunting for a needle in a hay stack. But now that i know how throttle position is represented internally it's easier to run another search. It seems that all the throttle stuff is always 16bit and wide open is represented by the value 11010 (0x022B) and surprisingly that value only shows up in 26 different "clumps" so now that i have that new information it may be easier to find the related maps. but the search also pulls up stuff like this:


i have no doubt that that is DBW related but that looks like two tables that are on top of each other. it would be easy to say that's just a table with 3 axis but i know what those look like in this ECU and that's not what that looks like at all. but if we plot it out it looks like a "resonable" throttle transfer curve. little lumpy but not ridiculous:


Also, the lumpiness may disappear with the axis values. since this isn't a normal table i have no idea what the column header values are. this graph assumes they are equidistant.
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post #43 of 79 (permalink) Old March 25th, 2019, 00:59
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This is good stuff. When I zero in on what variables to log I should be able to generate some tables and transfer functions for comparison with the binary. For now I have started with a series of screen captures. The first one is a test of pedal and throttle travel with engine off. This is in a bone stock 2007 Toyota Camry.

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post #44 of 79 (permalink) Old March 25th, 2019, 01:00
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The second test is with engine running in Park.

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post #45 of 79 (permalink) Old March 25th, 2019, 01:06
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This is a road test under different driving conditions - 1. Launch, 2. Gradual pedal increase in D, 3. Gradual pedal increase, manual select mode, 2nd gear.

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post #46 of 79 (permalink) Old March 25th, 2019, 13:35
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Do you have a good way to log those to text instead?

ideally we want the following so we can figure out the map:
-Pedal Position
-throttle blade position
-mass air flow
-absolute load
-rpm
-road speed
-gear# (is this a pid?)

with the above info it should become obvious which variables control the throttle curve (if any) in a stock application.

Ideally a 2009 or earlier rav4 would be even better to get this info from but while i expect the curves will be different i expect them to be linked to the same type of variables on both applications.
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post #47 of 79 (permalink) Old March 25th, 2019, 15:04
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Ok sure I can log to csv. Any particular test protocol?
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post #48 of 79 (permalink) Old March 25th, 2019, 15:08
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I'll analyze whatever i can get but if i could be picky i'd ask to see the following:

accelerate from 0-70 (or whatever the legal highway speed limit is near you) with the pedal at roughly 10% increments. at 10% it may not make it to 60, just abort the test at whatever speed it starts tapering off at.

That'll allow me to start building a map to visualize the input to output. with that data in hand i'll have more specific tests to run with an MR2 to confirm behaviour there.
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post #49 of 79 (permalink) Old March 25th, 2019, 16:29
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I'll try to get you the best data that I can.

When you say "pedal" which of the pedal PIDs do you mean? The thing that behaves the most like a pedal is the one labeled throttle manifold and goes from about 15% to 81% in range. But there's also those other pedals with behavior that I don't understand.

Is the test to be done in fixed gear? Gear 2 or 3 would work, any preference? I'll try to do both, for comparison.

I'll also check what other other mode 21 Toyota PIDs may be available related to the pedal and throttle.
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post #50 of 79 (permalink) Old March 25th, 2019, 16:31
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honestly this data is slow enough that it's probably best to just log all the pedal & throttle related pids.

i was assuming a sweep through the gears just in Drive because it may be related to gear state and this may help us know that a bit.
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post #51 of 79 (permalink) Old March 25th, 2019, 17:43
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Quote:
Originally Posted by merryfrankster View Post
I'll try to get you the best data that I can.

When you say "pedal" which of the pedal PIDs do you mean? The thing that behaves the most like a pedal is the one labeled throttle manifold and goes from about 15% to 81% in range. But there's also those other pedals with behavior that I don't understand.

Is the test to be done in fixed gear? Gear 2 or 3 would work, any preference? I'll try to do both, for comparison.

I'll also check what other other mode 21 Toyota PIDs may be available related to the pedal and throttle.
As far as I can tell, "Pedal Position D" and "Pedal Position E" are the actual outputs from the pedal. They should show the same data with a different scale. "Throttle position (manifold)" is the one I usually use for throttle blade position. There are a couple of other "throttle position" PID's, and from what I have seen they seem to track with the "manifold" PID, so I don't usually bother with them


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post #52 of 79 (permalink) Old March 25th, 2019, 19:03
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As far as I can tell, "Pedal Position D" and "Pedal Position E" are the actual outputs from the pedal. They should show the same data with a different scale. "Throttle position (manifold)" is the one I usually use for throttle blade position. There are a couple of other "throttle position" PID's, and from what I have seen they seem to track with the "manifold" PID, so I don't usually bother with them
We'll see this better when I have logs, but from looking at the road test video, for pedal D and pedal E

min max range
D 15.7 69.4 53.7
E 32.2 85.9 54

min is at idle, max is at WOT.

This is consistent with engine off.

min max range
D 15.7 69.9 54.2
E 32.2 85.5 53.3

Discrepancies can be attributed to de-synchronization of PID's. So it appears the two pedal signals move in tandem, they appear to have the same scale (or at least same range), but different offset.

The blade position tracks consistently with these pedal positions and it seems the same relationship with engine running or engine off. Just by eyeballing the videos I could give you a preliminary rough transfer function. I'll save that for when we have some numbers to work with.
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post #53 of 79 (permalink) Old March 25th, 2019, 19:42
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Ah what the heck I can't wait for numerical data I am going at it with advanced optical recognition just like any neanderthal would do it. This is what they teach in America's graduate schools.

The chart is at the bottom.

D E blade
15.7 32.2 15.7
25.5 41.2 18.4
14.3 40.0 19.2
19.2 35.3 16.1
19.6 35.7 16.5
21.6 36.1 16.5
25.1 40.8 20.0
25.5 41.2 19.2
29.8 45.9 23.1
31.8 47.8 25.5
33.3 49.0 25.9
34.5 50.6 31.0
34.9 51.0 31.4
36.9 52.9 34.9
37.6 53.7 36.1
38.0 54.1 36.1
39.6 55.7 40.8
41.6 57.6 45.9
42.4 58.0 45.5
42.7 58.8 47.5
45.1 61.2 49.4
45.5 61.6 53.3
47.5 63.9 53.3
48.6 64.7 61.2
52.9 69.0 63.9
51.8 67.8 67.1
58.4 67.8 74.9
58.8 74.9 79.2
68.6 85.1 81.2
69.0 85.5 81.2
69.8 85.9 81.2

PS. This will remain to be proved out but I did not on preliminary analysis detect any change in the shape of these curves under different driving conditions.

PPS. Classic example of sigmoid function.
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File Type: jpg Throttle vs. Pedal.jpg (43.5 KB, 12 views)

Last edited by merryfrankster; March 25th, 2019 at 19:50.
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post #54 of 79 (permalink) Old March 26th, 2019, 19:01
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I have not driven the car yet, but initial testing on the potentiometer are very promising. A pictures worth a thousand words right?



I did find the adjustment to be extremely sensitive, so it's possible that a logarithmic ("audio taper") pot would have been a better choice. Or perhaps an extra resistor in parallel, but I need to read up on that a little. The setting I'm at right now is about 1.6k ohm (out of 10k). I initially wanted a linear pot as I expected (i'm not sure why) to be at a higher resistance than that, which might have put me in the steep part of an audio taper pot. But 16% of full scale should be well within the flatter part of an audio taper.

EDIT: I take that back, based on the chart found on this page http://www.resistorguide.com/potentiometer-taper/ , 16% might well be past the knee point of most cheap audio taper pots (cheap pots actually being two linear slopes, not a true logarithmic curve). And getting into that steep part would make it even more sensitive.

I also found that if I went too far it would throw a P2138: Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation. But it seems happy where I have it now.
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post #55 of 79 (permalink) Old March 27th, 2019, 17:33
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Took it for a test drive this afternoon. Everything worked perfectly. No sign of throttle reduction at any of the RPM ranges that I hit, and the throttle sensitivity is greatly improved (reduced).

I also added a 10k resistor in series between the third pin of the pot and the ground side of the pedal circuit. This dramatically reduced the adjustment sensitivity of the pot, making it much easier to dial in the right value.
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post #56 of 79 (permalink) Old March 28th, 2019, 02:37
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Do you have a good way to log those to text instead?
I made some logs of acceleration runs trying to hold the pedal as much as possible at a fixed position for each run. The raw log file is attached. I did all these runs in 2nd gear. I chose a fixed gear to make it possible to sweep as much as possible of the rpm range on each run.

I made some visualizations based on the log.

The first is load (y-axis) vs rpm (x-axis) with the curves segmented by pedal position (z-axis/color).

The second is MAF (y-axis) vs rpm (x-axis) with the curves segmented by pedal position (z-axis/color).

Note that the pedal position is "Pedal Position E" in the OBD2 variables and it has a range of about 32 (no pedal pressure) to 86 (pedal to floor).

The third is very simple just speed versus rpm but it gives something interesting it shows the effect of the torque converter lockup which I found pretty edifying. I'll let people draw their own conclusions.

The final chart is Throttle Position versus Pedal Position segmented by MAF. Two interesting things in this chart: The concentrations of points in the form of "dots" correspond to the approximate fixed pedal positions that I attempted. And the second interesting thing is I did not get enough data collected at high pedal positions so I'll be repeating and adding more data soon. But the thing is, this is not showing much segmentation of the throttle versus pedal aside from scatter, which is kinda what I intuited and commented on in a previous post.
Attached Images
File Type: jpg LoadvsRPMvsPedal.jpg (89.0 KB, 8 views)
File Type: jpg MAFvsRPMvsPedal.jpg (75.1 KB, 7 views)
File Type: jpg SpeedvsRPMvsPedal.jpg (72.6 KB, 5 views)
File Type: jpg ThrottlevsPedalvsMAF.jpg (62.9 KB, 7 views)
Attached Files
File Type: zip trackLog-2019-Mar-27_18-35-02.zip (58.8 KB, 1 views)
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post #57 of 79 (permalink) Old March 28th, 2019, 18:36
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Thank you for that log. a few things come out of this:

1)Your pedal changes the throttle blade all the way up to 100%. Alex, does your pedal position E go beyond 86?

2)It does not look like the transfer curve between the pedal and the blade is relatively static and does not change with RPM or speed.

I'm wondering if this is a difference between the 5-plug and the 2-plug ECU. I haven't gotten in my car to see if i can feel what you guys are talking about but i assume i would have noticed the top 25% of the pedal not working sometime in the last 10 years or so.

so Alex, what was your raw value min and max on pedal position E?
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post #58 of 79 (permalink) Old March 28th, 2019, 20:38
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I have been using pedal position D for my testing, but as Frank noted, D and E are basically the same just offset.

Stock
Raw min-max on pedal position D: 15.69 - 76.08
Raw min-max on throttle position manifold: 16.08 - 81.57

With potentiometer correction.
"corrected" raw min-max on pedal position D: 12.16 - 58.82
"corrected" raw min-max on throttle position manifold: 16.08-81.57

Compared to Frank's range for pedal position D: 15.7-69.8


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post #59 of 79 (permalink) Old March 28th, 2019, 21:16
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I made a mistake when i said 86. Frank's range in the data given is 32.15 to 71.76 normalize it to start at zero and it's 0-39.61. Your range is 15.69 to 76.08 which means your range normalizes to 0-60.39 which is way wider than frank's. but interestingly Frank's throttle blade never actually goes to 86 so i suspect there's something actually limiting physical travel of the accelerator pedal in his car. as silly as it sounds, like they possibly designed the pedal travel without the carpet in there or something like that.

Frank, can you take the intake pipe off your car and seeing if your throttle blade actually opens all the way on your car?
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post #60 of 79 (permalink) Old March 29th, 2019, 00:41
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When I get back to the vehicle I will re-check this time removing all carpeting. I didn't think it was interfering but there is only one way to make sure. I'll also take a look in the TB.
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