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Only car #1 slows down when empty

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I'm running D132 cars with FUEL = ON setting on the CU.
I have noticed that the car on controller #1 progressively slows down when it runs out of fuel. Other cars do not.

So I did a test...

If I take the car on controller #2 (say) and re-assign it to #1, it too will slow down when out of fuel. If I then put it back on #2, it does not return to it's previous behaviour. Instead it continues to slow down on empty.

In other words, any car that is raced using controller #1 is now permanently programmed to slow down on empty tank, irrespective of which controller it is moved to after that.

I am running firmware from 13-Apr-2021 but have noticed this behaviour in previous releases as well.

Anyone else out there seen this?
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That's how it works.

Fuel = ON means the car remembers how much fuel it has. That's cool and all, but it's just a number. It doesn't actually affect how the car drives. For this kind of fuel, the amount of fuel in the tank stays in the car, no matter what ID it's on.

Fuel = Real means the CU controls how much fuel each car has, because it can also change how much power the car has depending on how much fuel it has. For this kind of fuel, the tank stays with the ID, not the car.

It's possible that I'm not understanding your explanation, but you might not have performed your test correctly.

With Fuel = ON (not Real), drive a car programmed to ID #1 until it runs out of fuel and slows down. Then, program that car to ID #2 and run it. It should be slow because it's out of fuel. Pull into the pit and refuel. Now, program the car back to ID#1. It should behave as it would with a full tank. This is because the CAR stores the fuel level in this mode.

With Fuel = Real, drive any car on ID #1 until it's out of fuel. remove that car, and put another car in it's place. Does it also drive as if out of fuel? Refuel it. Then, put the original car back on. It should now drive as if it has a full tank. This is because the CU stores the fuel level in this mode.

Now that I've said that as if I'm 100% sure I'm correct, I will say that I'm not 100% sure, and that I hope anyone with confidence will either corroborate that, or explain that I'm wrong. :)
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Hey Greg,

Thanks for the reply.

I now understand that that this is how it works but (for me) only on ID #1.

All my other cars on IDs 2-6 DON'T seem to slow down when they run out of fuel.

I'ts kind'a weird.
That IS strange.

Are you using any kind of software to control the system, such as an app through the App Connect?
You're real/on description is wrong, Greg. If you have a pit lane adapter unit in the track, the CU tracks fuel use, not the car chip. Real mode just means the CU will slow the car with a full tank, and speed the car up with an almost empty tank.

I refrained from answering this one, because there really isn't anyway for the described behavior to occur w/o some kind of software intervention. Or just someone mis-interpreting what they are seeing.
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Thanks, Bruce. I knew I was getting something wrong.

Is it the Fuel track, specifically, that's needed? The pit lane turnout pieces don't change this mode, just the Fuel sensor track being in the circuit, correct?

So, no Fuel sensor means cars track fuel, Fuel sensor in place means CU tracks fuel.

Fuel ON just means it's tracked, Fuel REAL means the car slows down with a full tank. In BOTH of these modes, and empty car just hobbles around with it's lights flashing (if present)?
The Carrera handling of fuel usage and the differences between fuel <on> and fuel <real> seem quite complicated and difficult to remember. And perhaps implemented with reduced functionality with some of the third party D132-compatible decoders? And if I remember correctly there are differences between BB and CU in how fueling at pit stops is handled between in-car decoder and the base unit?

Thanks to MrFlippant and b.yingling for helping clarify these subtle details.

Im a bit lost but if I understand the OP then the cars fuel usage behaves differently when re-assigned to another car ID... That is really strange.

Is this behaviour consistent with every car? If only one car doing this then could be a decoder microcontroller issue.
To answer Bruce's question, yes, I am running SmartRace software and I have used it to program fuel levels but the observed behaviour happens even without the software.

I've been doing more testing (without SmartRace) and have now discovered another of my cars (a red Ferrari 448 GTE) that never runs out of fuel even when I lower the fuel setting on the CU to 10%.

But that same car under SmartRace control does actually consume fuel during a race.

I'm kind'a over the slowing down thing. I don't think I care anymore if all the cars don't behave the same in this regard. In a serious race everyone will pit and refuel anyway.

The Ferrari's behaviour still has me intrigued however.
Some late model Ferrari (I forget the exact one) had an issue with the decoder FET that makes it run too fast. You might not mind it running too fast (depending on your layout and preferences) but this issue also affects the fuel usage, it will hardly use any fuel. Best to fix the problem.
The Ferrari is likely being slowed- but it has a FET that hides it.

Fuel use on Carrera is not that complicated. On a Black Box system (been over ten years now since they were sold), or a CU w/o a pit lane adapter track (again- ten+ years since pit lanes didn't include one of those), the car chip tracks fuel. Can't be reported to software, and there are likely third party chips that won't track fuel use.

On a CU system with a PLA- which is anything built and bought in the last ten+ years- the CU tracks fuel, the car chip does not, so fuel levels can be reported to software, and the car chip doesn't have anything to do with it. Fuel switch set to ON means fuel is turned on. Fuel switch set to REAL means fuel is turned on, and the CU will change a car's driving behavior to simulate the weight of fuel in the tank.

That's pretty much it.

The slowing of empty cars and flashing of lights does differ from PLA equipped systems and non-PLA equipped systems. But the latter are so rare, and their owners are so used to using them (after 10+ years) that it isn't worth going into.
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Interesting Bruce about the PLA systems, but I won't ask

Some info on cars that have FET issues...

The car decoders from the manufacturing line up to late 2018 are mostly OK. (It only became an issue in late 2018)

Car decoders from the start of 2020 are ok.

There was a period where they were not. There is a list of affected cars on another forum but...

Here is a link with the details that you may need to fix a decoder that is affected. Hopefully your retailer or distribution channel can help you but the link might be of help otherwise. There is another thread but probably not recommended if you haven't already followed along (it goes on for many pages) The fix uses a 2cent part.

One little thing that isn't mentioned in that link is that the resistor needs to be packaged on the board as tightly as possible to fit back into the chassis of some cars. Smaller resistors are better for the fix if you can find them.
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