MR2 Owners Club Message Board - View Single Post - 2GR Camry sensitive accel pedal
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post #42 of (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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