Autonerdz forums

I was searching around on the net for pressure transducers that will display dynamic pressures and I came up with some companies that sell them. The interesting thing is - they are built in to an actual spark plug! (there are other models) I am wondering if they will actually measure combustion pressures!???? As you can imagine, this could be a very useful tool! Here is the link to the sites. http://www.avlditest.com/?id=148&L=1
http://www.optrand.com/products.htm
http://www.intertechnology.com/Kistler/Pressure_Model_6117B.htm

I haven't analyzed the data sheet in detail yet, and I dont know if they are available to the end user....
But i am going to find out!

I believe the article is stating the transducer is installed along side an actual secondary circuit; it is a functioning plug.

I'll probably get shot down here but here goes 

Whilst these are very important for evaluating engine performance/design from an engineering stand point, I would see limited diagnostic information from combustion pressure and flame front characteristics.

Brad

I agree with you guys - to a point. If you don't have a huge computer to analyze the flamefront and 'knock' there is limited diagnostic value in these specialized transducers for us as techs. 
What I really find interesting about these is that i would expect to see them on cars for engine controls soon - once they become affordable.

Also, after some research, these are quite a bit different than a wps and a rigged plug. Some are specifically designed to show very specific information of whats going on in a cylinder. Some will show peak combustion pressures only, others are a lot more sensitive and show even more info - like the controlled explosion at the peak of the compression waveform.
Personally, I would be interested to see the even higher pressures created when the spark plug actually fires in a dynamic test. However, we can't really know until they become affordable and someone uses them for diagnostic purposes.
Also note that I listed it as possible future transducer in the title. Some of these (to actually show the controlled explosion)cost well over 1200 bucks apiece - not to mention the plug reach and gap would have to vary for each vehicle under test. Also, the hookup on most is through fibre optics. This is simply not practical for a technician. In that I have to agree!
You guys are brave - as much as a WPS costs - and useful as it is - there is no way I would put it under combustion pressures!
Here is another link to some waveforms created by these sensors - and how they are made. The same technology is going to be incorporated into injectors and glow plugs....
http://www.optrand.com/Papers/fisita98/fisita98.htm
I find new technology to be always interesting - keeps you ahead of the game a bit.....

Irwin,

I believe some of your information is flawed. It appears you are referring to permanent fault codes. For 50 percent of all 2010, 75 percent of all 2011, and 100 percent of all 2012 and subsequent model year vehicles (including 2012 model year medium-duty vehicles with 2011 model year engines certified on an engine dynamometer), before the end of an ignition cycle, the OBD II system shall store confirmed fault codes that are currently causing the MIL to be illuminated in NVRAM as permanent fault codes (as defined in section (g)(4.4.6)).

http://www.arb.ca.gov/regact/obdii06/19682clean.pdf (2.2.5)

The MIL will not be illuminated after a code clear, however, the permanent fault code does stay in memory until the PCM has run the exact monitor that failed it originally and then runs it and it passes. Once that happens, then the OBD system will clear it on its own. This was implemented to prevent cheating during an I/M program test.

As far as uninterrupted mode $06 data goes, I'm not so sure about that. My understanding is the only change here is for PFC storage.  

This technology is already on the road today.  Though it's not a gasoline engine the VW 2.0L TDI uses glow plugs that are cylinder pressure sensors as well.

http://www.beru.com/english/produkte/psg.php

Carl Grotti wrote on Jan 23^rd, 2011 at 4:47am:


It may be so, I haven't seen any of these vehicles yet. I think that 2012 models, so aug 2011, we'll be seeing the change. As far as I understood it, the dtc's will be set in the same manner (consecutive drive cycles... etc.) but the method for clearing them will change. Right now if i clear a code it clears out all of the diag. info, so the mode 6 data is reset, with the changes coming up, when a code is cleared it will not clear out the diag. info. So in order to truly clear dtc's we will need to prove them out. And when a code is cleared, you will only be clearing out that code. I also hear that the smog license requirements will include a hands on test for those who want to test and repiar, as well as a new test for testers only. I'm in california, so not sure if these changes will be effective in other states. In either case, we will be seeing soem changes, there's been talk of a ticketing sys. that will send a ticket by mail if a driver's eng. light has been on for longer than 30 days! (we'll see about that one).