ECU rule / standalone question (I promise I searched first...)

[veeman]

Can anyone summarize the new clarification on the ECU rule for IT cars or point me to the discussions here in these forums? I just looked for a while in the archives and can't find the info.

I was talking with some other IT racers and thought I heard that it's possible to run Megasquirt on some IT VW's...

This would make sense for ITB Golf's/Jetta's that could run electronic injectors because of the Digi allowance (some of those came with digi and vin rule allows cross-pollenization), but from what I read it wouldn't apply to ITC rabbits / rocco's since they always had purely mechanical injectors (plain Jane CIS). Is that right?

I could get by using the hall distributor for ignition signal, however, another recent post (concerning a BMW) here seemed to indicate that since pulley's are free, a toothed wheel could be added.

I've got some experience with 034 EFI (somewhat like Megasquirt) and think there would be some reliability / simplicity advantages to switching from CIS.

[JoshS]

I could get by using the hall distributor for ignition signal, however, another recent post (concerning a BMW) here seemed to indicate that since pulley's are free, a toothed wheel could be added.

Sure, you can add a toothed wheel ... but there's no allowance to add a sensor to read from that toothed wheel.

[GTIspirit]

Sure, you can add a toothed wheel ... but there's no allowance to add a sensor to read from that toothed wheel.

Maybe I didn't interpret this correctly:

9.1.3.D.1.e.

Any ignition system which utilizes the original distributor for
spark timing and distribution is permitted. Internal distributor
components and distributor cap may be substituted. Crankfire

ignition systems are prohibited unless fitted as original equipment.

I interpret this as saying that if you car didn't come with a crank trigger wheel, i.e. toothed wheel, you can't add one. So this now creates a disparity with newer vehicles that came from the factory with a toothed crank trigger wheel, meaning the open ECU rule benefits newer cars more than older cars. While I understand the SCCA doesn't try to make a completely level playing field, some cars are inherently faster than others, I'm pretty sure the SCCA wouldn't intentionally make a situation where some cars are offered more of an advantage than others.

9.1.3.D.1.a.6.

The engine management computer may be altered or
replaced. A throttle position sensor and its wiring may
be added or replaced. A MAP sensor and its wiring may
be added. Other existing sensors, excluding the stock air
metering device, may be substituted for equivalent units.

Maybe this is a tortured interpretation, but a four-window hall effect sensor has the same purpose as a crank sensor. But then there is the provision that original distributor must be retained.

[Ron Earp]

Oh boy!

[JeffYoung]

GTISpirit, in the humble opinion of this singular (and I am not speaking for the whoel ITAC here, they had good reasons for the result) that is exactly what was done (maybe inadvertently) -- newer cars with cam and crank position sensors can more readily take advantage of the open ECU rule v. older cars that read that position from the distributor.

My own personal experience with a Haltech system has been a nightmare trying to get a reliable signal from the distributor to the ECU.

Note that a crankwheel is legal because pulleys are free. But that doesn't get you where you need to be: you need a sensor too. As Josh notes right now, the rules don't specifically allow for the moving the sensor from the distributor to the crank even though the "equivalent" sensor rule doesn't talk about location.

Last, there is the prohibition on crankfire meaning no way no how can you fire the ignition (you could fire the injectors assuming your sensor is legal) with the added crank wheel.

On the other hand, note that MAP sensors and TPS sensors are already allowed to open up the playing field and make it easier to install an aftermarket ECU.

My understanding on why MAPs and TPSs were allowed is that they were perceived as having no performance advantage, while a crank wheel sensor does.

I think there is some arguable performance advantage to a MAP and a TPS on cars that don't have them -- they clarify and improve some of the inputs to the ECU.

But, the bottom line for me is that a motor's total power is restricted by design, cam and compression. Plenty of muscle car tests out there that show carbed cars making as much ore more peak power than an ECU unit. Where the ECU helps -- sometimes a lot -- is area under the cover, and that is the real advantage we are talking about here.

The issue is should we make it easy to open that up to all varieties of fuel injected cars by making all sensors legal, or should we try to limit creep and restrict the sensor rule?

Arguments on both sides.

[Ron Earp]

The issue is should we make it easy to open that up to all varieties of fuel injected cars by making all sensors legal, or should we try to limit creep and restrict the sensor rule?

Arguments on both sides.

You know my feelings on this and as the owner of a carbed race car I have the most to lose: open the damn rule up and let the fuel injected cars use any ECU and any sensors needed to make them work. At least the ECU cars would all be on a level playing field.

The carb guys, well, we chose our cars and they are getting on up there in years. Mine is 35 years old this year and almost 40 years old since penned and designed in Japan. C'est la vie.

[veeman]

Thanks for the input guys... Leaving the ignition aside, would it be considered legal to sub out the electronic (digifant style) injectors for the CIS mechanical units?

The version of 034 that I have can fire the injectors off of the existing hall sensor signal (although it's not what some people would argue to be the best method) and the digi injector cups / fuel rail *should* fit the 1.6 head (they fit my 1.8 GTI head). The TPS signal, intake air temp and vac signal should also be legal for that setup...

I just tried to comb through the GCR and I can't find a reference to the injector type...although it does indicate in the ITC spec line for the car that the rabbit that I have uses "Bosch CIS Injection"

[jlinfert]

Can anyone summarize the new clarification on the ECU rule for IT cars or point me to the discussions here in these forums? I just looked for a while in the archives and can't find the info.

I was talking with some other IT racers and thought I heard that it's possible to run Megasquirt on some IT VW's...

This would make sense for ITB Golf's/Jetta's that could run electronic injectors because of the Digi allowance (some of those came with digi and vin rule allows cross-pollenization), but from what I read it wouldn't apply to ITC rabbits / rocco's since they always had purely mechanical injectors (plain Jane CIS). Is that right?

I could get by using the hall distributor for ignition signal, however, another recent post (concerning a BMW) here seemed to indicate that since pulley's are free, a toothed wheel could be added.

I've got some experience with 034 EFI (somewhat like Megasquirt) and think there would be some reliability / simplicity advantages to switching from CIS.

No rabbits or roccos in IT period. Only the golf and jetta had Digi.
You can absolutely use the stock hall sensor with Megasquirt. There are several advantages to megasuirt, 1: better power 2: better fuel economy (yes on a race car!)
3: reliabilty 4: adjustability 5: inexpensive (I do installs with tuning and all parts for about the same price as a plug and play that is a megasquirt variant (just the hardware)

[veeman]

>>No rabbits or roccos in IT period. Only the golf and jetta had Digi.

By this do you mean that something like megasquirt wouldn't be legal for rabbits/scirocco's in ITC since they never had digi to begin with? Just trying to clarify... and yes, the reasons you listed are exactly why we'd want to go that direction. My car is running great (although a bit rich right now) and as much as I *cough* love CIS, something more modern / with easy parts availability would be a step forward