Speed governor/limiter (EU)

[Vlad Soare]

There was one guy posting here last year about his experiences, taking what I think was also a Bullit to the speed limit on autobahn, but I cannot remember the name of that thread. Maybe if you search here, you will find it.

Yes, but his Bullitt was tuned, so it's reasonable to assume that the speed limit (if any) had also been removed.

Sponsored

 

[Vlad Soare]

My GT had indeed a speed limit of 250 km/h in the PCM, but I couldn't test it. I was only able to reach 248 km/h on the dash before I had to slow down.
I've removed it in the meantime, not because I actually intend to drive that fast, but because the idea of an electronic limiter bothers the hell out of me.

Npole's reasoning is correct. No matter how accurate or inaccurate the speedo may be, I expect it to be the reference for the limiter. I mean, if the car knows you should not be allowed to exceed X km/h, and it also knows that you've reached that speed (even if this knowledge may be wrong due to tire size, tire pressure, colour of your eyes, or it being a Tuesday), then it must cut off the gas. Displaying one speed on the dash, while using another speed (calculated God knows how) as a reference for the limiter, would be daft. I don't doubt it's technically possible, but I think it's unlikely.

 

[Michael_vroomvroom]

Indeed, Npole's reasoning is correct. No matter how accurate or inaccurate the speedo may be, I expect it to be the reference for the limiter. I mean, if the car knows you should not be allowed to exceed X km/h, and it also knows that you've reached that speed (even if this knowledge may be wrong due to tire size, tire pressure, colour of your eyes, or it being a Tuesday), then it must cut off the gas. Displaying one speed on the dash, while using another speed (calculated God knows how) as a reference for the limiter, would be daft. I don't doubt it's technically possible, but I think it's unlikely.

Agreed, it would not make any sense. If OP has an odb2 dongle and forscan, perhaps he could use that to verify what the speed limit is set to, since you say you can view it in the PCM.

 

[Vlad Soare]

Unfortunately you can't see it with ForScan. You need a tuning device and software, like HPtuners.

 

[raptor17GT]

i would suspect the primary source of the rotation of the wheels (or gearbox in different cars) will have some accuracy variation as will whatever does the rotation to speed translation as will the display medium. For example, an older car of mine got it's speedo reading direct from the gearbox in 12v pulses, which it then dropped to 5v to send onto the ECU so it knew the speeds and then applied the 180kph speed limiter. So there you have potential for variation between what the speedo displays and what the ECU sees. Does it make a difference in the real world, no it should not.

if your speedo was showing 40 but you were doing 50 and getting tickets all the time then yes it's a problem but showing 272 when you're doing 268? Not an issue. Remember, speedos (in the EU for sure) cannot under read but they are allowed a certain over read.

 

[Michael_vroomvroom]

i would suspect the primary source of the rotation of the wheels (or gearbox in different cars) will have some accuracy variation as will whatever does the rotation to speed translation as will the display medium. For example, an older car of mine got it's speedo reading direct from the gearbox in 12v pulses, which it then dropped to 5v to send onto the ECU so it knew the speeds and then applied the 180kph speed limiter. So there you have potential for variation between what the speedo displays and what the ECU sees.

That's a decent point related to older cars or cars with an analog speedometer display, but OP should have a digital speedometer display (I think all recent EU mustangs have the digital dashboard), so I don't think this would apply in OP's case.

 

[npole]

if your speedo was showing 40 but you were doing 50 and getting tickets all the time then yes it's a problem but showing 272 when you're doing 268? Not an issue. Remember, speedos (in the EU for sure) cannot under read but they are allowed a certain over read.

Showing speed is not an issue, it's computed and will never be accurate.
The question was about more how it reached that read speed, since the governor should read the speed from the same source of the speedo (it's all digital, you can't go wrong or having different values, unless there's a bug in the software).
An explanation is that the two sources would be different, but why? It doesn't make sense to calculate the speed in two different ways.
A more plausible explanation is that we (at least I) assumed that the max top speed set on the EU Bullitt is 263 Km/h, while effectively it's not, but higher.
Another explanation is that my car has a different firmware, with the issues I had with it, and the "tests" ford did on it (including uploading a new software to sort the "misfire issues" I had), thinking that they applied a custom version or a non stock firmware isn't crazy as it sounds.
I think I'll live with the mistery.. until someone else with a EU Bullitt will push it down the road.

 

[Vlad Soare]

We need someone who has a Euro-spec Bullitt and an MPVI2+ interface (or any other tuning device for that matter) to confirm this.
I have an original HPT file from a Bullitt, but it's US-spec, so it may not be relevant.

My Euro GT had 250 in that field.
Maybe Euro Bullitts have a different limit?

 

[npole]

Is it a common interface to find around? I don't know any specific tuner around me... it would be interesting to read my own car to figure it out. Do you know if the dealer and their "official" interface does have this capability?

 

[Vlad Soare]

https://www.hptuners.eu/products/

The software is free for reading, but you need to purchase so-called credits for writing. A 2018+ Mustang requires four credits.

 

[npole]

I have a standard odb2/ELM372 interface (it works with ForScan), their software will work with it?

 

[Vlad Soare]

Sadly, no. The software only works with that particular interface.

 

[npole]

Argh... well I have the inspection next month, I'll ask the guy if he has anything to read the value eventually.

 

[raptor17GT]

That's a decent point related to older cars or cars with an analog speedometer display, but OP should have a digital speedometer display (I think all recent EU mustangs have the digital dashboard), so I don't think this would apply in OP's case.

mm it was driven by PWM so that indicates non analogue though it was a sweep needle system. Anyhow, OP is arguing about how two displays disagree with each other or one onboard system doesn't match GPS, clearly has never watch Aircraft Investigation! For the shts and giggles if there is a hub dyno / rolling road that can read that fast, strap it to the dyno and see what it says v the speedo. So for the sake of a few kph I hope he gets his answers

 

[raptor17GT]

Showing speed is not an issue, it's computed and will never be accurate.
The question was about more how it reached that read speed, since the governor should read the speed from the same source of the speedo (it's all digital, you can't go wrong or having different values, unless there's a bug in the software).
An explanation is that the two sources would be different, but why? It doesn't make sense to calculate the speed in two different ways.
A more plausible explanation is that we (at least I) assumed that the max top speed set on the EU Bullitt is 263 Km/h, while effectively it's not, but higher.
Another explanation is that my car has a different firmware, with the issues I had with it, and the "tests" ford did on it (including uploading a new software to sort the "misfire issues" I had), thinking that they applied a custom version or a non stock firmware isn't crazy as it sounds.
I think I'll live with the mistery.. until someone else with a EU Bullitt will push it down the road.

for safety reasons yes it does but in a car, likely not worth the lines of code.
You assumed a top speed and went past it, therefore your assumption was proven wrong at that point or was it? Absolutely digital can be wrong, like anything it can be wrong. Anyhow, hope you get it sorted

Sponsored