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Discussion Starter · #1 ·
Seems to be a lot of heresay on FFIM auto stuff, it's 2021 and technology has changed immensely. Still seems like piggy backing the factory ECU is the easiest way to tackle controlling the auto trans. I've searched every forum I could find for two weeks with no real luck. Moving ECU and steering reservoir is easy enough. But 2 questions to overcome, does the MAF need to see airflow for the gas gauge to work and what does the trans need from the TB to function correctly?
 

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Seems to be a lot of heresay on FFIM auto stuff, it's 2021 and technology has changed immensely. Still seems like piggy backing the factory ECU is the easiest way to tackle controlling the auto trans. I've searched every forum I could find for two weeks with no real luck. Moving ECU and steering reservoir is easy enough. But 2 questions to overcome, does the MAF need to see airflow for the gas gauge to work and what does the trans need from the TB to function correctly?
You'd likely still need MAF if you still want the fuel gauge, gotta know the load at a given throttle position
 

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Discussion Starter · #5 ·
You'd likely still need MAF if you still want the fuel gauge, gotta know the load at a given throttle position
That's not really a big concern. I understand what they mean about the MAF for the fuel gauge now. So my only concern is figuring out what to keep plugged in to keep the trans happy
 

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That's not really a big concern. I understand what they mean about the MAF for the fuel gauge now. So my only concern is figuring out what to keep plugged in to keep the trans happy
You see, I don't have an auto and didn't know the auto trans needed to be played with
 

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Are you not able to use say a Lexus V8 TB on the FFIM? Like a LS430 TB? Pretty sure those are very similar wiring wise. I wouldn’t know exactly what the trans needs to see in order to function properly. I would assume just TPS but that’s a LARGE assumption on my part.
 

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I wouldn’t know exactly what the trans needs to see in order to function properly. I would assume just TPS but that’s a LARGE assumption on my part.
Yeah, that’s what I am thinking too. I’ve never researched documentation for what exactly the A650 needs to shift, because I also have an MT. The ETCS-I TB signal wires are VT, VTA, VPA, VPA2. There’s a couple DBW motor wires as well. Mainly there are two TPS signals and two APPS signals, both of which I bet play a role in shifting. I’ll tell you this, a GTE VVTi TB will plug right up and work off the GE VVTi ecu, so that may be an option for you. I don’t think just relocating it to the trunk will do anything. It’s going to need to be attached to the accelerator pedal and functional.
 

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Discussion Starter · #9 ·
Yeah, that’s what I am thinking too. I’ve never researched documentation for what exactly the A650 needs to shift, because I also have an MT. The ETCS-I TB signal wires are VT, VTA, VPA, VPA2. There’s a couple DBW motor wires as well. Mainly there are two TPS signals and two APPS signals, both of which I bet play a role in shifting. I’ll tell you this, a GTE VVTi TB will plug right up and work off the GE VVTi ecu, so that may be an option for you. I don’t think just relocating it to the trunk will do anything. It’s going to need to be attached to the accelerator pedal and functional.
This is what I'm running into with my research. I haven't found one single solid lead on an FFIM swap. I'm wondering if it really would work if I extended all wiring and hid the TB in the trunk that the ecu would be none the wiser
 

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wondering if it really would work if I extended all wiring and hid the TB in the trunk
Man, so I don’t know how much you know about the IS300 ETCS-I DBW TB. So I’m not an expert but I’ll give you a crash course. It’s not a pure DBW setup. There’s a mechanical connection from the accelerator pedal to the TB. This is responsible for like 0-25% TPS. Then from like 26-100% TPS the DBW motor controls the throttle plate. So it’s a hybrid mech/electronic setup, kind of an in between total mechanical and total DBW. Was supposed to afford the ability to limp the car home on mech throttle if there was an issue with the DBW part. So there’s not a sensor on the IS300 accelerator pedal - like modern DBW cars have. The APPS is actually on the TB. So that’s why I don’t think just relocating it will work. It may keep you from getting a MIL but I can’t see how it will help the trans shift without changing values like it does when the throttle cable is connected. If the trans just needed a static value you could ohm the various sensors and and install appropriate values resistors in the throttle body’s place. But I don’t think it’s that easy.
 

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I can tell you that you will need to be selective about your wire choice, i played around with a throttle relocate a few years back and found issues if there was any extra resistance by the wires themselves. I was getting error codes due to the wires. It would be possible to relocate to the trunk, others have done it to fit under the seat or behind the glove box so the trunk isnt much further.
 

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Man, so I don’t know how much you know about the IS300 ETCS-I DBW TB. So I’m not an expert but I’ll give you a crash course. It’s not a pure DBW setup. There’s a mechanical connection from the accelerator pedal to the TB. This is responsible for like 0-25% TPS. Then from like 26-100% TPS the DBW motor controls the throttle plate. So it’s a hybrid mech/electronic setup, kind of an in between total mechanical and total DBW. Was supposed to afford the ability to limp the car home on mech throttle if there was an issue with the DBW part. So there’s not a sensor on the IS300 accelerator pedal - like modern DBW cars have. The APPS is actually on the TB. So that’s why I don’t think just relocating it will work. It may keep you from getting a MIL but I can’t see how it will help the trans shift without changing values like it does when the throttle cable is connected. If the trans just needed a static value you could ohm the various sensors and and install appropriate values resistors in the throttle body’s place. But I don’t think it’s that easy.
This isn't wholly correct.

While the cable/pedal does indeed have about 25% command authority over the actual throttle butterfly, it's only there to give you something if the throttle motor dies. When everything is working correctly, the pedal never mechanically opens the butterfly. It's only when the system malfunctions and the throttle motor goes dead... In this case, the first ~75% of pedal travel is useless - it's only that last 25% of movement that finally starts to act on the butterfly, opening it ~25%.

Aside from this, the particulars of our DBW setup are basically the same as any other DBW arrangement. There is a pedal position sensor with two rheostats - one increases voltage as pedal position increases, and the other DECREASES as pedal position increases. These two redundant signals go the ecu, which in turn sends a signal to the throttle motor to open the butterfly. A TPS sensor then provides feedback to the ecu so that it can confirm the butterfly has moved the right amount (and so the ecu can make necessary adjustments).

I have no idea what strategy the ecu uses to control the transmission, but it seems logical to me that actual throttle position would be more important than pedal position.

The ecu already has diagnostics in place to compare TPS to APS, and determine if everything is hunky dory. So in choosing/calculating shit points and line pressures, I would guess the ecu is paying attention to TPS. But I would assume that would need to be a "qualified" TPS signal, implying the ecu has read both APS signals, decided they were happy, commanded the throttle motor to a target position, and then looked at the TPS feedback signal, and seen the throttle butterfly is indeed in the correct position.
 

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So, does the TPS not need to change, for the transmission to shift?
Not sure about specifics, i just tried running new wires to the remote DBW motor and the TPS and had a spare throttle body set up to see how it could be done. I think i ran the standard TB APS with it cocked over 45 degrees so it would engage direct, but it gave errors which i narrowed down to the dodgy wires i was running. Ran out of time in the end, that was a few years back now, been too busy to bother since then lol
 
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