Do modern car computers prevent conversion?

Post by **AgentSpanky** » Wed, 04 Jun 2008, 04:53

Hi all,

I'm just beginning to plan out a conversion, and am looking at a donor car that is reasonably modern (ie waterproof and reasonably comfortable).

I'm pretty confident that given an old Mk II Escort, I could whack an AC drive and motor with a few batteries in without a massive amount of trouble. It occurs to me, though, that with modern cars, it might not be so easy - has anyone got some pointers?

I'm thinking that I would like to keep the inside as stock as possible, with the exception of removal of the gear lever. The dash would be standard, albeit with a charge meter and perhaps diagnostics.

The problem as I see it could be that all the electronic systems in the modern car are so tightly coupled that ripping out the engine might do more than just lighten the load on the front wheels..

A hypothetical situation:

After removing the engine, I no longer need the engine computer, so toss that.

As part of the integrity/security systems, the body computer interrogates the engine before enabling the ignition circuit, as well as the airbags. Getting no CAN response, the airbags are disabled.
Since the wheel speed sensing logic was integrated in the engine computer, there is no wheel speed feedback, either.
The reverse lights are on a LIN network, and were enabled via a switch on the gearbox, also binned.
On the same network, as a safety precaution due to the reverse lights not responding, the brake lights are also disabled.
The clutch actuator 'keep alive' signal is no longer happening (clutch thrown away), so an error scrolls continuously across the message area in the dash...

Is this the sort of stuff that happens in new cars when you throw half of them away? This is the part the scares me the most about the whole process - ending up with a car with some system(s) crippled by the absence of some innocuous part I threw away earlier, when it wasn't powered up and I couldn't tell.

Any advice, reassuring stories/tales of disaster?

Thanks..

Post by **markrmarkr** » Wed, 04 Jun 2008, 18:13

I was worried about exactly the same thing, and basically concluded that there are only two options:

1. Steer clear of new cars.

2. Learn how to deal with car computers. This isn't as bad as it sounds. In fact there was an article in last months Australian Personal Computer (APC) about it, which makes it look like a walk in the park. But somehow I doubt it.

The other annoying thing about it is using parts from a modern car may be a problem too. I'm thinking of electric power steering. Typically at high speed you need less assistance from the power steering, and thus may save some energy when traveling at speed. If you don't have it wired up, it may go to a default mode and still work, and even pass rego inspection, but there will likely be little improvement in energy-economy.

Also a lot of the modern digital controllers have this option, so it may be worth investigating. Particularly AC controllers, but I've even seen some motors with it.

I'd be very interested to see if anyone has any actual hands on experience of this stuff too.

Post by **Thalass** » Tue, 10 Jun 2008, 18:17

That is a good point, Spanky. I was thinking about it the other day, driving my wife's 06 corolla around. It would make a great conversion car for her, as the driving experience would not change much. But if I was going to convert a car for my wife and spawn to drive around in, there's no way I'd be disabling the airbags or other safety features.

Perhaps if the motor controller could hook into the CAN bus and emulate the various things that were removed during the conversion? I don't know of any motor controllers that do this, but if I was to design my own that is something I'd look into.

Post by **AgentSpanky** » Fri, 27 Jun 2008, 06:14

..I'm still looking for a copy of that magazine at the Library - someone always has it out!

The controllers have outputs to control various accessories? Wow - I hadn't heard about that. That sounds very complicated for the controller..
I've done a bit of work with automotive CAN networks, and know how demanding the various sub-systems can be with regard to frequency and content of messages. I'll have to investigate, and get back to the forum.

I'm still pretty keen on the idea of airbags and abs, etc.. Hopefully it won't prove to be too much of a hassle.

Post by **a4x4kiwi** » Fri, 27 Jun 2008, 15:31

This is a real concern for newer vehicle conversions. I think a good inspection of the factory service manual (if available) for a vehicle should reveal what relys on what.

I will be interested in your findings AgentSpanky. (if thats your real name)

I know Les in Sydney (not on this forum unfortunatly) is doing a brand new Triton. It would be interesting to know how he is working around these systems.

Regards,
Mal

Post by **Richo** » Sat, 28 Jun 2008, 04:14

Which car has all of those?
I don't want it cos the brake lights stop if the reverse lights fail!

Aren't airbags a dummy device that when power is applied it blows - get and aftermarket accelerometer and measure the peak for stupid driving going over bumps and sidesways or a short rally stint etc then set it 2-3 times higher.
I'm sure you could figure out how to rewire a brake and reverse light.
Why keep the clutch anyway do you want to rev your quiet eV motor at the lights?
The speed sensor is still there I doubt that it need to got to the computer for ABS/ALB.
The speed sensor for the dash is in the gearbox usually and is likely to not going into the computer. Otherwise fit an aftermarket speedo/odo.

Problem solved.

Go the Escort - they have more character than the modern plastic cars.
Plus it's rear wheel drive should make it a good eV conversion.
There was also heaps of rally/performance parts to upgrade to to make breaking and handling better.
Stick on some big forrest arches and you got yourself a real head turner - esp if you pull from the lights at warp speed!

Post by **AgentSpanky** » Mon, 30 Jun 2008, 17:21

Richo wrote:Aren't airbags a dummy device that when power is applied it blows - get and aftermarket accelerometer and measure the peak for stupid driving going over bumps and sidesways or a short rally stint etc then set it 2-3 times higher.

I'm totally not going to set the limit myself. There is a lot of maths and filtering to prevent unintended deployment, as much as unintentional non-deployment. Manufacturers spend literally man-years tuning the algorithms. From Wikipedia:

Today, airbag triggering algorithms are becoming much more complex. They try to reduce unnecessary deployments (for example, at low speed, no shocks should trigger the airbag, to help reduce damage to the car interior in conditions where the seat belt would be an adequate safety device), and to adapt the deployment speed to the crash conditions. The algorithms are considered valuable intellectual property. Experimental algorithms may take into account such factors as the weight of the occupant, the seat location, seatbelt use, and even attempt to determine if a baby seat is present.

As far as I know, in the states new cars must detect the weight of a front seat passenger and make allowances for that in the rate of deployment. The difficulty is developing this algorithm has led to Tesla motors (as well as Lamborghini, I believe) getting special exemption despite not having this capability to sell their cars legally.

Richo wrote: I'm sure you could figure out how to rewire a brake and reverse light.
Why keep the clutch anyway do you want to rev your quiet eV motor at the lights?

I can absolutely retrofit some non-networked light clusters, but I want to keep as much stock as possible, for reliability (and to not waste my time rewiring!).
I don't want the clutch, that's my point. Once removed, I want all the other sub-systems still to function, hence my question.

Richo wrote: The speed sensor is still there I doubt that it need to got to the computer for ABS/ALB.
The speed sensor for the dash is in the gearbox usually and is likely to not going into the computer. Otherwise fit an aftermarket speedo/odo.

Modern cars all have electronic dashes - the speedo dial is actually a small stepper motor that you send a CAN message to: "Display 4350 RPM, please".
I will be throwing away the gearbox and driveshaft, anyway, so if the speed sensor was there, I wouldn't have it anymore. I can pretty easily send the correct CAN message to the dash cluster, but it might require some other message that I don't know about to fully function, again, hence my question.

Richo wrote: Stick on some big forrest arches and you got yourself a real head turner - esp if you pull from the lights at warp speed!

I totally agree that would be easier, and certainly fun to have a very quick electric MkI - but I still would prefer a waterproof, soundproofed car with ABS, etc. I will look into it further, but appreciate your thoughts..

Thanks

Post by **Richo** » Tue, 01 Jul 2008, 07:01

Ah so you think an accelerometer with FFT on DSP might be the go for the airbag...Hmmm I'll have to think about that some more.

Is there a "CAN sniffer"?
You could use it to monitor/save the transmission with a laptop while you drive.
That way you can see what code they sent to all parts of the car including the digital dash, reverse lights and brakes.

Ummm if you are throwing away the gearbox and the driveshaft how will you transfer the power?
Will you be direct to the diff/cv's?

Anycase since you are direct can you put a sensor on your motor and send the info to the dash?

Post by **Richo** » Tue, 01 Jul 2008, 07:06

Anyone willing to test out the airbags til I get it right?!?

Post by **AgentSpanky** » Tue, 01 Jul 2008, 15:15

lol. that's what i was thinking..!

Any descent CAN diagnostic nodule can 'sniff' the network, and log all messages. The only hassle with that is figuring out which of the several thousand messages a second are the ones you're interested in!
If on the other hand, it is possible to get a manual of all the messages a particular model uses, then it would be relatively simple (if not a little time consuming) to fake any or all messages required with a simple microcontroller stuffed in the network, somewhere..

Yes, two smaller AC motors direct drive to the rear: smaller I^2.R losses, same top speed, although two controllers.

Absolutely I can send my own speed message to the speedo cluster, my original fear was there would be some other message/notification it needed that I was unaware of..

-

Still no-one with any practical experience of any of these problems with a nice simple answer?

Post by **Kecon** » Wed, 23 Jul 2008, 02:13

Hi AgentSpanky, All e-pilots and Wannabees

I'm from Denmark and total new here, but nice forum You got here.

I have been thinking of my own conversion too for some time now.
This about a newer donorcar to get Airbag and ABS, have also been of my conserns.

I read about an american guy who converted a total new 2007 Yaris, but he is guite scarse about details. When I asked him he only replied "No problems with the electronics, easy system to integrate with" but I'm not quite sure he was telling all !?

http://www.electricyaris.com/

Post by **Richo** » Wed, 23 Jul 2008, 03:20

http://www.electricyaris.com/

Working link (Spaces removed)

Post by **Kecon** » Wed, 23 Jul 2008, 03:58

Thanks Richo

Post by **markrmarkr** » Wed, 23 Jul 2008, 16:00

I found this on the site for an open source Corolla based in Finland. This was in the FAQ:

1.11. How will the driving control systems (ABS, ESP) used in modern vehicles operate when the original fossil-fuel engine is repelaced by an electric motor?

Even with their fine titles and complicated calculations, driving control systems only generate commands that either speed up or slow down the vehicle’s engine. These can be measured and adapted to suit electric motors. In most cases, these transducers and computers associated with driving safely are located in separate units located around the vehicle. Interfering with these during the conversion process is not the intention. The upgrade system is connected to the vehicle network and distributes information in the same way as in the fossil-fuel arrangement.

here is a link.
http://www.sahkoautot.fi/eng

So it looks like they are addressing the issues but we don't get any visibility. I found this a bit dismissive, but in fairness they are concentrating on the Finish community at the moment. I guess it's about time English speakers got some of their own back.