Ignition cut

[Andres]

Anyone out here have ever implemented their own ignition cut or fuel cut system. I´m aware that there are some commercial systems that do so, but i´m wondering how they do it, if they use power transistors or something like this and which ones. We want to implement fuel and ignition cut in our injection system and we are looking on how to do it.

Equipo F-SAE USB
Universidad Simón BolÃ*var
VENEZUELA
www.formulasae.grupos.usb.ve (http://www.formulasae.grupos.usb.ve)

[B Lewis @ PE Engine Management]

Hello Andres,

Our system (PE-ECU-1) will do ignition or fuel cut automatically based on overspeed or a digital input (for shifting, traction control, etc). In order to do the ignition cut, we just don't charge the coils for those cycles. What system are you using? If you would like some specific help on implementing this into a system that doesn't offer this feature, contact me offline at brian@pe-ltd.com

Brian Lewis
Performance Electronics, Ltd.
www.pe-ltd.com (http://www.pe-ltd.com)
"Complete Engine Management Systems for $798"

[Mi_Ko]

We would need one too. Our Haltec doesn't have an ignition or fuel cut option, which we would need for clutchless shifting.

If someone has an cheap alternative how to build it, please let us know.
(Or if someone has an cheap spare ECU)

2002/03 University of MARIBOR - Team Member

[B Lewis @ PE Engine Management]

Mi_Ko,

If you are interested in a new system, we sell one to FSAE for $798 and includes ECU, harness, crank trigger wheel, software and manual. It is well suited for small, 4-cyl engines and will handle fuel and ignition (both with cuts available).

Here is a link to what other customers (including FSAE teams) have said about the system: Testomials (http://www.pe-ltd.com/testimonials.htm)

Check the system features at: PE-ECU-1 Features (http://www.pe-ltd.com/products/ecu_hardware.htm)

If you have any questions, please contact me. If you stick with the Haltech, contact me offline (brian@pe-ltd.com). I can offer some suggestions about how to do this. Good luck.


Brian Lewis
Performance Electronics, Ltd.
www.pe-ltd.com (http://www.pe-ltd.com)
"Complete Engine Management Systems for $798"

[Mi_Ko]

Thanks Brian!

I know your sistem. I'm not our engine guy, but if I would choose a ECU it would be yours. (Are you planing to send someone to formula student?)
BTW:
Does the unit has a launch control function? This is one thing i'm missing, because we had some problems with spinning wheels at the accelaration. (together with the tyres. We lost at least 0.5s at the event because of that)

The trouble is, we have a small, and I mean SMALL, budget (Slovenia is a small land and nobody is interested in sponsorship). We'll have to run our old haltec (We know it's crap) until we find a good sponsor.

We already have some ideas how to do the cut. (some relays on the coils wired with the shifting button) But whe will sure have problems when doing this. I'll contact you when we come so far. (And sure for a new ECU,... in the near future)


Thanks for now.

2002/03 University of MARIBOR - Team Member

[Chris Boyden]

You could try and put a power mosfet or an N-channel HEXFET from International Rectifier with the Drain and Source connections in series with the coil driver output. If you keep the transistor in a "normally on" state by keeping the gate high. The Resistance from the drain to the source of these HEXFETS are very very low, therefore it doesn't absorb very much of the voltage that will be tranferred to the coil input. When the ignition cut is needed, take the gate of the transistor low, which will turn it off and prevent the signal from energizing the coil.

This is what I was planning on doing at first, but if you use an ECU that has an input that will trigger an ignition cut, then it's too much work.

[BeaverGuy]

Our team uses the lower rev limiter on our MSD for an ignition cut during shifts. The method works but it isn't ideal.

[Igor]

If you're using a relay to cut the 12V feed to the coil(s), put a 20V 5W zener across the contacts to prevent them from burning up. (we didn't use a setup like that, but I imagine the contacts will be much happier with the zener)

Igor

[Daygo Nighthawk]

We run a Electromotive TEC-II on our test bed car, and it has an auxillary rev-limiter function. I recently wired it up with a relay for shift-cut (for those on our team who aren't very good drivers/shifters). We have paddle shifters and beefy solenoid shifters (convenient but heavy, and sucks on a car without an alternator on it..). Using this aux rev limiter isn't an ideal for shift cuts, and on downshifts, it doesn't help much. Also, it removes our ability to use that aux rev-limit for launch control (independent launch control function, at least..) Basically, we had an extra relay in shop and it took all of 5 minutes to set-up, so I just went with it (cheap and easy, just how our old car was built). An op-amp in this situation would speed up the cut-response delay.

A hint on 'standalone' ignition cut: all you have to do, is make zero voltage DROP across the coils.. as for fuel cut, the same goes for voltage across the injectors.

___________________________________
College is a fountain of knowledge . . .
and the students are there to drink.

[Andres]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Boyden:
You could try and put a power mosfet or an N-channel HEXFET from International Rectifier with the Drain and Source connections in series with the coil driver output. If you keep the transistor in a "normally on" state by keeping the gate high. The Resistance from the drain to the source of these HEXFETS are very very low, therefore it doesn't absorb very much of the voltage that will be tranferred to the coil input. When the ignition cut is needed, take the gate of the transistor low, which will turn it off and prevent the signal from energizing the coil.

This is what I was planning on doing at first, but if you use an ECU that has an input that will trigger an ignition cut, then it's too much work.<HR></BLOCKQUOTE>

Boyden, that´s what im looking for a Power Depletion Mosfet so its normal position will be on (whithout the need of an external voltage applied to the gate), and when the time come to cut the ignition a voltage signal from a microcontroller can "turn the transistor off" to disconnect the coils. But i havent been able to find any Power Mosfet that can handle the current needed by the coils to do ignition.

Equipo F-SAE USB
Universidad Simón BolÃ*var
VENEZUELA
www.formulasae.grupos.usb.ve (http://www.formulasae.grupos.usb.ve)

[Chris Boyden]

Dude, Check out irf.com
They have some n-channel enhancement mode mosfets that'll handle up to 150 http://fsae.com/groupee_common/emoticons/icon_eek.gif amps, (yea ,150 amps) with the proper heat sink. You can also put a high voltage (up to 100 volts, 12 volts no problem) Darlington pair inverter (ULN2803, www.ti.com (http://www.ti.com)) connected to the gate of the power transistor. You'll get the same action as a depletion mode device, which I cannot find. The darlington driver will accept TTL inputs and you can control a 12 Volt device on the output.

[Andres]

I wanted a Depletion Mosfet to have a simplified circuit, but you are right the Darlington pair and the Transistor will do the job. I will keep looking for the Depletion Power Mosfet, maybe there is one that i can use. Thanks for the advice, i´ll check also the irf website

Equipo F-SAE USB
Universidad Simón BolÃ*var
VENEZUELA
www.formulasae.grupos.usb.ve (http://www.formulasae.grupos.usb.ve)

[Ryan Schoffer]

you can just cut the signal from the crank angle position sensor to cut the fuel and spark

the factory ECU will throw a code, but thats no biggie

Vehicle electronics leader

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[Frank]

rough as guts approach.. I LOVE IT

[B Lewis @ PE Engine Management]

Mi_Ko,

We don't have an explicit launch control function with the PE-ECU-1 but with the ignition/fuel cut inputs and adjustable outputs, it's pretty easy to do. The next generation ECU will have it in addition to alot of other nifty features (Is 60 meg of datalogging enough for everyone? http://fsae.com/groupee_common/emoticons/icon_wink.gif

If I can help, drop me an email offline at brian@pe-ltd.com

Brian Lewis
Performance Electronics, Ltd.
www.pe-ltd.com (http://www.pe-ltd.com)
"Complete Engine Management Systems for $798"

[DoItDoug]

Got a release date for that new PEL ECU version? We've got a launch control setup for this year already, but we WILL be switching to a new ECU next year and would like to start setting things up on a spare dyno ASAP. We'd love to find a system with ECU functions integrated with traction/launch stuff (without selling off kidneys to afford it!). Keep us posted...

Doug Temple
'02 VT FSAE
www.vtmotorsports.com (http://www.vtmotorsports.com)

[ben]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by DoItDoug:
Got a release date for that new PEL ECU version? We've got a launch control setup for this year already, but we WILL be switching to a new ECU next year and would like to start setting things up on a spare dyno ASAP. We'd love to find a system with ECU functions integrated with traction/launch stuff (without selling off kidneys to afford it!). Keep us posted...

Doug Temple
'02 VT FSAE
http://www.vtmotorsports.com<HR></BLOCKQUOTE>

For an ECU with integrated traction and launch control check out www.dtafast.co.uk (http://www.dtafast.co.uk).
The P8Pro is £850+VAT (VAT is 17.5%) not sure what the deal is with US customers on that.

All Formula Student teams get 25% discount from them, so I suspenct they'd do the same for an American team.

Ben

University of Birmingham
www.ubracing.co.uk (http://www.ubracing.co.uk)

[B Lewis @ PE Engine Management]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by DoItDoug:
Got a release date for that new PEL ECU version? We've got a launch control setup for this year already, but we WILL be switching to a new ECU next year and would like to start setting things up on a spare dyno ASAP. We'd love to find a system with ECU functions integrated with traction/launch stuff (without selling off kidneys to afford it!). Keep us posted...

Doug Temple
'02 VT FSAE
http://www.vtmotorsports.com<HR></BLOCKQUOTE>

Hi Doug,

We will have Beta versions ready this Winter. Full production should be around Spring '04. What are you guys using now and what do you like/dislike about it?

Brian Lewis
Performance Electronics, Ltd.
www.pe-ltd.com (http://www.pe-ltd.com)
"Complete Engine Management Systems for $798"