no it wasn't unrelated, and yes I am going to fuel cut
no it's not harzardous, as I've looked into it. There arn't too many ways of doing it. The Astra/Cav TC works in the same way if it needs a quick response (drop clutch in 1st!), it cuts fuel. Normal driving it reverts back to the throttle sdjustment, but that doesn't give a quick enough response to stop you breaking traction in 1st gear fun
i reckon i can get wheel slip all the way up the main road mate, if you are gonna push it, the fuel could be cut for 20 odd seconds.
with the huge amount of air going in, running lean aint a good idea, but i dont know how efficient these systems are, maybe it will be an instant cut, but running my sort of power then it would be constantly cutting in when its wet lmao
(a) if theres no fuel in a cylinder, it won't fire, i.e. no power output. If I cut two injectors evey two revs, thats half power! that will stop the wheel spinning pretty quick!
(b) If it cuts in, it will give you maximum traction, as it should respond quick enough to maintain effective grip.
Don't see how efficiency comes into it TBH mate, I cut the power feed, it stops! efficient or not. However, if I altered the throttle body like, the Vauxhall TC does, then I would suffer from the problem you mention, the engine responds too slow to a butterfly position change, so injector cut it must be. (They fuel cut on vauxhalls, BTCC cars, and F1 cars )
Only inertia from the flywheel would be able to keep the wheel turning, and theres not enough power in the flywheel to spin a wheel.
The alogrythm isn't as cut n shut, as wheel spinning, cut power til it isn't, then apply max power. It needs to work in a closed loop, in the same way the ECU responds to fueling + the lambda sensor + a knock sensor.
This will be the hardest part to get right, i.e. how much power to try and apply, too much, and it'll break traction, if it does, then it's not a traction control unit!
they also rebuild btcc and f1 cars every 100 miles or summat and we all know how good vauxhalls are
i probably just got the wrong end of the stick, i wouldnt want to purposefully misfire my engine on any cylinders
if there is definately zero fuel in each cylinder just before the injector would theoretically fire and you miss it out then its not gonna ignite, but i dunnae like it.
I think Rob has a point - unless you make the traction control almost 'digital' - the moment you try and soften off the way it cuts in and out you will go through a lean period which does ignite - combined with the sort of ignition advance you'll be running at the point where it cuts in it'll detonate, no question about it.
it takes surprisingly little fuel in the mixture to combust - I accidently turned my FPR down to 0 psi awhile ago and the engine would almost idle, purely on the tiny bit of pressure the pump could deliver straight into the fuel rail.
TC systems which work by cutting engine power invariably use ignition timing control as the primary cutting mechanism - purely controlling fuel going in is not a good idea unless you make it completely on/off - but that'll make it terrible to drive...
Maybe modern cars do fuel cut, but one thing is a car manufacturer/bosch spending millions on making sure the technology is reliable - another thing is a garage mechanic doing experiments! Sounds like a possibly very expensive experiment to me.....
Time for a bit of brainstorming.
you could make an anti-spin device absolutely external to the engine and its management?
I´m thinking... What if one could make the ECU believe that the engine is knocking excessively, and the ECU would then retard ignition?
Could perhaps work, provided that the ECU is actually able to retard timing enough to sufficiently back down on power. And provided that the ECU wouldn´t take too long adjusting back to optimal timing.
OK, I've discussed this on DIY_EFI a while ago, and the majority of people on there were happy to say that fuel cut would be fine.
The 'better' way if you want to complicate the system a little is to retard the timing, it doesn't make the system much more complicated, and maybe I'll even include that on the prototype board so that I can monkey with it. err, infact it maybe easier.
The cycle works by cutting an injector out altogether, i.e. for one whole intake stroke, that cylinders injector is OFF, no fuel. It's an SFI system, so theres no chance of sucking in fuel from another injector. Also, there will not be enough fuel vapour around the inlet manifold to ignite in the cylinder. The result is just a misfire, if I wanted to be safer still, I could impede the spark on that cylinder too.
On some systems, i.e. traction control within turbo applications, it's common just to cut the spark. This has the result of chucking the unburnt fuel out, and keeps the turbo spinning. But I didn't look too far down that road. I felt that there was more chance of detonation whilst compressing the fuel mixture than if I cut the fuel on the cylinder.
hmmm, maybe I'll cut spark + fuel then on that cylinder.
I have known these systems to be OK, and work on 4 and 5ltr cars in America, where a few projects have already been successful.
The Knock sensor cannot be used to adjust timing enough, all the Motronic 2.5 system has apparently is the 98 + 95 RON maps, I would need to retard further than that if I wanted to stop breaking traction. There is also only two states, and I can't guarantee what the ECU will do.
Retarding the timing has a fast response, and allows smoother power adjustment.
I can take control of the coil I suppose, and then I can either cut spark, or retard the timing. It's only 1 extra input
ahh, yeah, forgot about that site, theres a few good signals on there.
There are teeth all the way around, and then two teeth missing at CLY1 TDC.
I've no idea at the moment, how I'm going to detect CYL1 TDC. That might seem strange after what I've just said, but all the timings are dependant on engine revs! It's not so easy to detect CYL1 TDC at 1k rpm, and CYL1 TDC at 6k rpm. The 'break' signal is a different length at all rpms