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nothere
30-08-2004, 04:30 AM
here is a link to what may be THE knock control system. Among other scenarios the spark plug is charged (becomes a sensor)and informs a computer of what has happened in that cylinder, the computer then advances, retards or maintains timing.
So you have an instant reading of what has happened in a cylinder after ignition. It can interpet knock and misfire. If your water injection had failed the plug would inform the ignition circuit if the cylinder had detonation.
this is one result of a search for " ion sensing ignition systems"

http://www.fs.isy.liu.se/~larer/Projects/main.html

b_boy
09-09-2004, 09:26 AM
Yes, that paper has been cited on the boards but in a different context. Saab supposedly built some cars with Wi and that system but they never made it out to the people. Richard L. mentioned they were bought by GM at the same time and maybe that killed the program.

A sensor like that might be just the trick for tuning WI.

Richard L
13-09-2004, 12:14 AM
The ionisation knock detection technique is very clever and accurate but at the same time requires a great deal of processing power, I believe the ECU has a very powerful DSP chip on board.

From the article, you can see how the controller was able to recover after receiving a large change in frame-front propagation speed due to the humidified air.

You would equally be impressed how the system also copes well with water injection rate beyond 25% w/f ratio!

See the link below:

http://www.aquamist.co.uk/dc/coollinks3/index/rally/saab/press/press.html

Such a shame that the WI never made it to the productin line. :sad:

SaabTuner
20-09-2004, 12:02 AM
Hey, I posted a link to the PDF version of that dissertation a while back. I agree the IGS system would be ideal for WI.

My Saab uses the Trionic 7 engine management (considerably more complex and more powerful than the Trionic 5 they were using in that test) ... I hope to eventually be able to modify it as they have, only internally. I'd love to be able to market a chip for WI using an Ion Feedback signal.

A few other cool things that Ion signal can do:

1. It can measure (if calibrated) the EGT for each cyllinder, for each individual combustion. That could make tuning much easier as you could more easily spot differences in EGT between cyllinders.

2. The ion peak represents the burn rate multiplied by the cyllinder pressure, and is a VERY good knock descriptor. Almost unwaveringly a cyllinder will detonate when the BRxCP is equal to some fixed amount for any given octane. If the air temp goes up, coolant temp goes up, or ignition timing is too far advanced it will all show up on that curve, and as long as the peak is kept below the knock threshold for that octane there won't be any detonation.

3. It can detect the A/F in each cyllinder for each combustion. That could be a very useful thing for the ECU to know, as it would give it immediate feedback about the results of its injector duration and throttle position etc.

4. By far the most amazing thing it can do is spot combustion differences. Differences in combustion of up to 20% are normally seen. Only the very highest end of that 20% causes knock. If you could use a feedback signal to design a piston/combustion chamber that caused say 10% variation instead of 20% you could theoretically increase the power 10% without detonation.

Sorry if I sound a bit over-enthusiastic ... I've been sorely temped to just whip out my ECU and play with it ... but obviously that would be a fool's errand as I simply don't have to tools, or software, to do anything with it. :( Oh well.

I may have also thought of a quicker way for the ECU to get a feedback schedule for ignition timing without resorting to the computation of two gaussian curves to match least-squares fit scenarios. It'd be really wicked to see if I could impliment that with a good WI setup for mileage purposes.

Adrian~

SaabTuner
23-12-2005, 03:04 AM
This company's Ion-Sensing system was brought to my attention recently: http://www.delphi.com/pdf/ppd/pwrtrn/gas_ignics.pdf

Now you can adapt the Ion-sensing knock system to almost any vehicle. :)

SaabTuner
23-12-2005, 03:05 AM
This company's Ion-Sensing system was brought to my attention recently: http://www.delphi.com/pdf/ppd/pwrtrn/gas_ignics.pdf

Now you can adapt the Ion-sensing knock system to almost any vehicle. :)

Greenv8s
23-12-2005, 01:57 PM
That looks dead sexy, but how much ????