TPS closed ADC value changes

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Nightsknight45
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Joined: Thu Oct 28, 2021 2:31 am
Location: Tampa FL

TPS closed ADC value changes

Post by Nightsknight45 »

As the title states, my TPS ADC value when the throttle is closed changes everytime I start the car after having it sit for a few hours. The full-throttle ADC value will stay consistent though. I am using honda CBR1000 bike throttles with an adapter harness I made from the Miata TPS plug to the CBR's TPS. This causes my car to run richer at low rpm and idle, I'm not sure if the TPS itself is at fault or if the wiring is the issue. I verified that the throttle is fully closed physically so I don't think the problem lies there. It's annoying to have to recalibrate the TPS whenever I need to drive...

Tune: https://rusefi.com/online/view.php?msq=1041

High value is closed and low value is full throttle. It's supposed to do that.


Anything I should check before I buy a replacement TPS and redo my adapter harness?
nmstec
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Re: TPS closed ADC value changes

Post by nmstec »

We've had a very similar problem on another car. Please confirm with a multimeter your voltage.

Last time this was a problem with the TPS itself, it was changing resistance with temperature.

Also we can't see your values, because your tune has no logs attached to it.
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Nightsknight45
Posts: 34
Joined: Thu Oct 28, 2021 2:31 am
Location: Tampa FL

Re: TPS closed ADC value changes

Post by Nightsknight45 »

The car is reading around 4.5 volts when closed and around .30-.35 volts at W.O.T. I know those values should be swapped but that's how the honda TPS works in my situation.



Here is a link to a datalog I took yesterday: https://rusefi.com/online/view.php?log=850
nmstec
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Re: TPS closed ADC value changes

Post by nmstec »

I mean check it when hot, then check when cold. See if theres a difference with multimeter.
"Dave B. 5:03 PM
Mark is an ass but by far the most potent combination of knowledgeable ass, smart ass, get it done ass and determined ass. and his ass consistently puts in time."

-Dave B, Hero, Tuner, and probably has a car.
mck1117
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Re: TPS closed ADC value changes

Post by mck1117 »

Nightsknight45 wrote:
Tue May 31, 2022 2:26 pm
I know those values should be swapped
BTW there's no such thing as "should be swapped" - that's the point of the TPS calibration process. So long as the sensor does something linear, it does the right thing. Electronic throttle bodies have a redundant pair of sensors that are usually roughly opposite, so one of them is always "backwards" as you describe, but it's by design.
Nightsknight45
Posts: 34
Joined: Thu Oct 28, 2021 2:31 am
Location: Tampa FL

Re: TPS closed ADC value changes

Post by Nightsknight45 »

nmstec wrote:
Tue May 31, 2022 5:57 pm
I mean check it when hot, then check when cold. See if theres a difference with multimeter.
Ahh I gotcha. I'll post with an update sometime tomorrow
Nightsknight45
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Location: Tampa FL

Re: TPS closed ADC value changes

Post by Nightsknight45 »

mck1117 wrote:
Tue May 31, 2022 5:59 pm
Nightsknight45 wrote:
Tue May 31, 2022 2:26 pm
I know those values should be swapped
BTW there's no such thing as "should be swapped" - that's the point of the TPS calibration process. So long as the sensor does something linear, it does the right thing. Electronic throttle bodies have a redundant pair of sensors that are usually roughly opposite, so one of them is always "backwards" as you describe, but it's by design.
Ok I see what you mean. I guess I was comparing the open and closed values from my stock setup. Thanks for the information
Nightsknight45
Posts: 34
Joined: Thu Oct 28, 2021 2:31 am
Location: Tampa FL

Re: TPS closed ADC value changes

Post by Nightsknight45 »

nmstec wrote:
Tue May 31, 2022 5:57 pm
I mean check it when hot, then check when cold. See if theres a difference with multimeter.
Alright, im getting around 4.33 volts when cold and I got around 4.34 volts when warm. I've seen up to 4.35 when cold previously. This is when the throttle is closed.
Nightsknight45
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Joined: Thu Oct 28, 2021 2:31 am
Location: Tampa FL

Re: TPS closed ADC value changes

Post by Nightsknight45 »

Bought a new tps and the problem seems to have been remedied.
Simon@FutureProof
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Re: TPS closed ADC value changes

Post by Simon@FutureProof »

We also had a similar problem and it was due to sensor drift when it was hot.
Something to do is check the raw voltages/ADC when the sensor is cold and then warm it up to see if it changes.

We were seeing drift in both the low and high end of the sensors signal, solved completely with a Honda CRV sensor.
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