Electronics > Projects, Designs, and Technical Stuff

Catching car's ignition signal

<< < (8/8)

cmcraeslo:
Nice setup you got there. The fuel system simulator - is that your own creation?

I usually deal with aftermarket ECUs, this is the 2nd or 3rd time that I'm trying to do anything "ignition like" on the standard ECU. I have engine simulator, that is able to generate wheel triggering and if you hook up original ECU, it does the cranking, firing up the coils etc. I cant use it in this case as this particular ecu has immo so it doesn't fire up and I wanted to make it simple. As I said, when ecu is operating with low power signals, I can handle that and I'll probably just make an external box that will catch high power signals and convert them into low power (and vice versa).

I'm going to try few other ideas from this topic next week and report if i'm able to get anything on the scope. Current measuring seems pretty good idea although catching correct dwell will probably be tricky in this case due to different firing ramp. What I dont want is to have this tweaking for every other car. Seemed very straight forward job from the distance :(

mikerj:

--- Quote from: cmcraeslo on August 05, 2020, 02:47:52 pm ---
--- Quote from: mikerj ---Why would fuel cut be any slower than ignition cut?  With either one a cylinder could be cut for a single firing cycle if needed.

--- End quote ---

On full throttle, the amount of fuel going into the intake is huge, basically, you could fire all injectors at once all the time and it would not make a difference (would just be more fuel consuming). It takes some time for the air and fuel to mix so cutting 1 or 2 cycles of the injector, does not make a a lot of difference in reality. This is needed when shifting gear because the reaction needs to be instant and the longer you unload the engine, the harder it will shift. Ignition on the other hand is what drivers the car so every interruption in that, disturbs the car, which is what is needed.

--- End quote ---

Great in theory, but popular motorcycle quickshifters such as the Power Commander manage to work perfectly well by cutting fuel.

cmcraeslo:
Motorcycle has never been hard to shift at full throttle. They're very light, basically no load on the gearbox, low torque and very high rpm - you can shift that as long as you're able to disturb it a little. With cars, it's a lot different. Add a turbo with huge load and it will very different scenario. That's why, the solenoid shifters work well on bikes, but struggle with cars.

mikerj:

--- Quote from: cmcraeslo on August 07, 2020, 08:21:39 am ---Motorcycle has never been hard to shift at full throttle. They're very light, basically no load on the gearbox, low torque and very high rpm - you can shift that as long as you're able to disturb it a little. With cars, it's a lot different. Add a turbo with huge load and it will very different scenario. That's why, the solenoid shifters work well on bikes, but struggle with cars.

--- End quote ---

No load on the gearbox because the quickshifter cuts fuel to remove loading!

A friends rally car has a 2L engine making around 285bhp at ~9k RPM with a Sadev sequential gearbox which uses fuel cut for shifting as well, so car engines are not really different.  However with a monster turbo pushing large quantities of fuel into the cylinder I can understand how this could be a problem.

cmcraeslo:
@mikej - would love to see your friend's parameters for the flatshift. Does he only uses fuel or adds fuel cut to the ignition cut/retard combination (that would be my guess).

Navigation

[0] Message Index

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod