ETB with single TPS input - 2016+ GM/Daewoo

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ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

Is it possible to allow using ETB with only one TPS signal? The 2016-2023 Chevy Spark has ETB but only one TPS. Maybe I can connect the same signal to primary and secondary TPS channels?
GM LV7 throttle controls
GM LV7 throttle controls
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

Wow interesting!

Do you have part number? Do you have a unit on a bench outside of car? Did you confirm if it's analog wire or maybe SENT?
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

PS: just finished my coffee and now I really think that GM 12673014 is SENT

Good news is microRusEFI can be modified to work with SENT. Do you have specific plans for this Chevy Spark?
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by mck1117 »

Or, if this is for an ETB retrofit to some other engine, there is probably another ETB that’s mechanically the same, but analog TPS instead of SENT that may be easier to use.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

Update, it is SENT. That is not a term I was familiar with before now, but the pinout for the factory ECU (Bosch E84) says SENT1 for the TPS pin. I assumed it was a potentiometer based on the symbol on the diagram, as well as the diagnostic info in the manual describing variable voltage.

What would it take to make MRE work with SENT ETB? I do have a 40mm Bosch Motorsport ETB here that I can make work, I'm guessing that would be the simplest solution.

The engine is an LV7 1.4L from a 2017 Spark. I have swapped it into an off-road vehicle with a hydrostatic transmission. This sort of drive arrangement requires a variable speed engine governor, to smoothly limit the maximum engine rpm to protect the pumps from overspeed, and to provide constant rpm regardless of engine load. A normal rev limiter will not work, it needs to provide full power at governed rpm. I currently have it running on the factory ECU, using an ESP32 microcontroller for governor. The ESP32 measures RPM, uses a PID loop and two analog outputs to simulate the Chevy accelerator pedal. The problem I'm having is that the OEM throttle control is not direct or linear. A very small change in pedal position input results in very large change in RPM, especially in the 3000-3600 rpm range where I need to govern the maximum speed. At 3000 RPM, a 0.5% change in pedal position results in 500 rpm change or more, and even using the factory pedal as input it is very difficult to hold the engine at a steady rpm manually. So my ESP32 governor, which works well on another engine with a servo attached to a manual throttle body, cannot control this engine without a lot of hunting and surging. There are no options for editing the throttle control in the factory ECU, and the ECU goes failsafe if I try to take control of the ETB directly, so I have decided to try an aftermarket ECU. I already have a MRE that's not being used so that's why I'm here.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by mck1117 »

MadGoatCustoms wrote:
Sun Feb 12, 2023 6:41 pm
What would it take to make MRE work with SENT ETB? I do have a 40mm Bosch Motorsport ETB here that I can make work, I'm guessing that would be the simplest solution.
Yes, running a conventional analog throttle body is the simplest solution.

SENT support on rusEFI is in its infancy, and if you want something that "just works", SENT is not the best route.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

Have to remove one capacitor, and I would have to add a couple of lines of code. Looks like myself and Matt have different takes on it - my take please consider being first real SENT user :)
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

I've got no problem being the test mule for SENT, but I would like to have this project wrapped up as soon as possible. I can dedicate nearly unlimited time to testing, and I have a very good understanding of hardware and electronics, but I'm a novice when it comes to coding. I did write my own code for ETB control with the ESP32, but I got stuck when trying to overcome static friction. My control works pretty well using just a PID loop and feedforward, but has trouble making small changes in position. I suspect it would work well enough on a normal car, but for a governor control which is constantly changing direction or making small adjustments to maintain a preset rpm I'm not so sure it would be acceptable. I think my next move is to hook up a spare analog ETB with MRE on the bench and see how it responds compared to my own controller. I haven't looked into the code, it's mostly over my head, does rusefi compensate for throttle friction?
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

OK, I wired up a Bosch 0280750149 ETB. I'm impressed with the ETB control, no doubt it will work fine for me. So now it's a matter of fabricating an adapter to fit it to the engine, or getting the SENT TPS to work and use the original ETB. AndreyB, How soon could you have firmware available for testing SENT?
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

70% chance to have it by Saturday
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

Sounds good, let me know when you have something. I still need to set up my triggers and other stuff.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

MadGoatCustoms wrote:
Sun Feb 12, 2023 10:37 pm
OK, I wired up a Bosch 0280750149 ETB. I'm impressed with the ETB control, no doubt it will work fine for me.
Any chance you could upload your happy tune and a good long happy log? Having some issues with my own bench setup at the moment want to compare your logs against mine.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

Nevermind another bench setup works as expected.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

I've discovered an issue with my setup. ETB only works with USB connected. As soon as I disconnect the USB cable from my laptop the throttle powers off. Reconnect and it powers on. It doesn't matter if Tunerstudio is running or not. Any idea what's wrong?
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by mck1117 »

MadGoatCustoms wrote:
Mon Feb 13, 2023 6:02 pm
I've discovered an issue with my setup. ETB only works with USB connected. As soon as I disconnect the USB cable from my laptop the throttle powers off. Reconnect and it powers on. It doesn't matter if Tunerstudio is running or not. Any idea what's wrong?
we've seen this before, can you hop on our slack channel and we'll chat? https://rusefi.com/forum/viewtopic.php?t=1198
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

Not much progress so far but hope to have news by Tuesday
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

No rush. I made an adapter to fit the Bosch ETB with analog TPS. Engine is running and tuned well enough for some testing. Throttle control is much better (more linear and predictable) than with the stock ECM with it's torque based control strategy, but I'm still not sure if it's going to work. Seems that governing engine speed across a wide range of RPM and varying loads is a lot harder than I could have ever anticipated.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

AndreyB wrote:
Sun Feb 12, 2023 10:38 pm
70% chance to have it by Saturday
Done

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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

Awesome. I should have time to test it on the Chevy Spark engine in the next day or two.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

Another thing I wanted to mention, GM is using 10kHz to run the ETB, and it is virtually silent. When I use the ESP32 at 10Khz it makes an audible noise, but less than MRE at 3khz. The noise is not an issue for me, I am just curious why we are limited to 3khz, the TLE9201SG is good up to 20khz.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

Code: Select all

! Matt says: The problem is the driver chip. Tle9201 can't do 20k. The drivers are too slow. On purpose to reduce EMI
#define ETB_HW_MAX_FREQUENCY 3000
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

?? The data sheet for TLE9201SG says it can work up to 20khz.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by mck1117 »

That 20khz line in the datasheet is sort of a lie.

The datasheet says this:
image.png
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So while it's "good" up to 20khz:

Worst case the switching time of a full cycle could be 80us. 1 / 80us = 12.5khz.

Best case the switching time would be 10us.

Best case 10us switching time at 20khz would be 10us worth of switching in a 50us cycle. During that switching time, the device is dissipating significantly more power, since partly on MOSFETs are a resistor.

The total power dissipation for an hbridge like this is roughly:

frequency * (E_rise + E_fall) + duty * P_on

where
E_rise is the energy dissipated during turn on
E_fall is the energy dissipated during turn off
P_on is the (resistive) dissipation while on

Increasing the frequency increases total dissipation because while the duty is the same, you're incurring more instances of the fixed cost of the switchings.

The other concern is linearity - if a significant amount of your cycle is occupied as the switch time, 40 vs 50 vs 60% duty cycle will not linearly map to 40-50-60% current as they should with ideal switches.

I've tried a TLE9201 with a real throttle at higher frequencies, and even managed to hit overtemp protection from the inefficiency of switching more often.
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

I removed C53 from my MREv5.4 and connected ETB SENT signal wire to AN temp 3, selected AN temp 3 as SENT input and GM type 1. I get error "No ICU on selected SENT pin".
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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by AndreyB »

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Re: ETB with single TPS input - 2016+ GM/Daewoo

Post by MadGoatCustoms »

Do I need to use AN temp 2? In latest snapshot firmware it lets me select any of the AN temp inputs.1&2 were already used for IAT and CLT so I picked AN3, and removed it's corresponding capacitor C53. What does "no ICU" mean?
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Re: ETB with single TPS input - 2016+ GM/Daewoo

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Re: ETB with single TPS input - 2016+ GM/Daewoo

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