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Ion-sensing w/knock control

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Ion-sensing w/knock control

Posted by Morris Ahten at August 04. 2009
How about adding a Ion-sensing system similar to the Delphi or Saab Trionic systems. Searching the web there is lots of information regarding the operational specifics and some circut design. I believe that is the way to handle Knock detection and provide more efficient engine operation. How about it? Thanks, Mo-

Re: Ion-sensing w/knock control

Posted by Ashley Duncan at August 05. 2009

Yeah, we have looked at that before...   Note that we have recently developed a new clever digital knock detection device and added full individualy cylinder knock detection features to all G4 ECUs.

Re: Ion-sensing w/knock control

Posted by Daniel Powell at August 06. 2009
How sensitive is this "clever digital knock detection device" to noise? Specifically all the knock sensors I've run in the past have been fooled by the noise of shattering rock against the bash plates underneath the engine.

Re: Ion-sensing w/knock control

Posted by Morris Ahten at August 14. 2009
My understanding is an ION-Sensing system is very sensitive and able to make adjustments as necessary for each combustion cycle. Using a small electric current running through the spark gap, it can sense combustion efficiently, and detect knock with extreme accuracy. Again my understanding is this type of system is superior and less costly then a "knock box". Try and put yourself in the manufacturer's place. My guess is since Link has created their own seperate detection system and need to realize a return on their investment, it does not make sense to engineer a new strategy, even if it's better and more cost effective then their existing design. I was really hoping LINK was going to engineer ION sensing ignition system. Ashley, thanks for responding to my earlier post, and please let me know if I'm on the mark here. Best regards, Mo-

Re: Ion-sensing w/knock control

Posted by Morris Ahten at August 14. 2009

Previously Morris Ahten wrote:

My understanding is an ION-Sensing system is very sensitive and able to make adjustments as necessary for each combustion cycle. Using a small electric current running through the spark gap, it can sense combustion efficiently, and detect knock with extreme accuracy. Again my understanding is this type of system is superior and less costly then a "knock box". Try and put yourself in the manufacturer's place. My guess is since Link has created their own seperate detection system and need to realize a return on their investment, it does not make sense to engineer a new strategy, even if it's better and more cost effective then their existing design. I was really hoping LINK was going to engineer ION sensing ignition system. Ashley, thanks for responding to my earlier post, and please let me know if I'm on the mark here. Best regards, Mo-

One more note --- ION sensing does work on an individual per cylinder basis using the spark plug as the sensor. :) Thanks again to all!

Re: Ion-sensing w/knock control

Posted by Morris Ahten at August 14. 2009
There is a considerable amount of informatoin on the VEMS website regarding ION sensing, how it works, and specific elements. Some links are broken, however thie is a considerable amount of information. http://www.vems.hu/wiki/index.php?page=IonSense I recommend having a look at this. Like I said, I would be thrilled if LINK would implement a similar technique. C'mon Ashley! talk'em into developing this! Cheers, Mo-

Re: Ion-sensing w/knock control

Posted by Phil Williams at August 17. 2009

I've had a look at the information you have provided. Seems like a good idea, but i  disagree with "Again my understanding is this type of system is superior and less costly then a "knock box"." for the simple fact that 99% of vehicles on the road do not run CDI from factory which means this would need to be installed before even considering the costs of the knock controller. Installation would also be far more difficuilt as each spark plug needs its own interface, where with the standard method one knock sensor can be used to detect individual knock on up to four cylinders using data windowing techniques.

We appreciate the suggestion but I don't think any development will be done on this anytime in the near future.

Re: Ion-sensing w/knock control

Posted by Morris Ahten at September 18. 2009

Previously Phil Williams wrote:

I've had a look at the information you have provided. Seems like a good idea, but i  disagree with "Again my understanding is this type of system is superior and less costly then a "knock box"." for the simple fact that 99% of vehicles on the road do not run CDI from factory which means this would need to be installed before even considering the costs of the knock controller. Installation would also be far more difficuilt as each spark plug needs its own interface, where with the standard method one knock sensor can be used to detect individual knock on up to four cylinders using data windowing techniques.

We appreciate the suggestion but I don't think any development will be done on this anytime in the near future.

Hi Phil! Thanks for replying to this post. For the rest of the readers of this forum, I'm adding a little more information which better explains how ION-Sensing ignition system works. It's included below in bold text. Link's ECU's are clearly very well engineered. I think it's a business opportunity to be one of the only aftermarket manufacturer's to offer something like this with your products. It would offer Market differention from your competitors. My hope is perhaps Link would re-consider offering this type of system. ION-Sensing seen as a very realistic technology to utilize. It's offerred by numerous OEM's and it's becoming more wide-spread all the time. - GM 4 Cyl engines using the Delphi engine Mgt use this type of control. Even the lowly Chevy Cobalt! - Harley-Davidson bike engines, - Saab uses in their Trionic ECU, - BMW on the M5 V10 and M3 V8 - Porsche --------------------------------------------------------------------------- Ion sensing measures the electrical resistance of the burning gas in the chamber via the spark-plug gap. A burning hydrocarbon flame contains free ions, which can carry a small electrical current. The electrical resistance of the flame is dependent on many things, one of them being the pressure of the gas (higher pressure -> lower resistance). If the gas does not burn, it is an isolator (infinite resistance). A lot of modern gas kitchen appliances use that property to sense if the gas flame is lit to find out when the ignitors can be switched off. Saab uses ion sensing in models. During knock there are pressure waves and spikes in the burning gas the chamber. These pressure waves (a few kHz frequency) get accoustically conducted into the engine block. That's what a knock sensor listens to. They also show up as rapid oscillations of spark-gap resistance that can be detected there even better, but more expensively because of the relatively large processing requirements. Those oscillations of resistance are not susceptible to false noise from piston slap or general engine noise. Engine phasing can be determined as well. If the ECU has control over individual coils, it fires 2 coils at the same time like a waste-spark system, using the 2 cylinders that are 360 deg out of phase (one at the end of the compression stroke, the other at the end of the exhaust stroke). Then measures on which cylinder the spark results in buring gas and from that knows which cylinder is at or near the top of the compression stroke. Because of the pressure sensitivity of resistance it is also possible (with a lot of realtime signal processing) to determine the peak pressure point in the cylinder and from that fine-regulate ignition timing. Ignition misses (once the correct engine phase is known) can be detected also because they result in infinite resistance of the spark gap (no burn). From the signal shape of the resistance curve over crank degrees one can also diagnose partial burns where the gas did not ignite fully. Again requires a lot of signal processing and averaging because the burn process is statistical and changes from stroke to stroke. All the best, Mo-

Re: Ion-sensing w/knock control

Posted by Ashley Duncan at September 18. 2009

Hi Morris,

   Thanks for taking the time to look into ion sensing.  We appreciate your feedback.  As with all feature requests, your ideas will be added to our requests list.  All requests are prioritised based on customer and dealer feedback and scheduled for development.  Should ion sensing become a highly sought after feature you can be assured that it will be added to our ECUs in good time...

Ashley

Re: Ion-sensing w/knock control

Posted by Danny Cornutt at January 05. 2011
Has there been any accommodations for ion-sensing yet? I am looking for an ecu that will support this feature.
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