Re: Fuel Enrichment Device

[brett@kodak.com (Brett VanSprewenburg)]

> 
> At 06:55 PM 1/14/98 -0800, you wrote:
> >> 
> >> I've been studying the Bentley manual, and the EC article on the Techtonics
> >> Tuning CIS-E fuel enrichment device.  I'm more than 90% of the way into 
> >> reverse engineering it.  (I'm an engineer by trade, so I feel qualified
> >> in using such statements :-) )  What I've got left to learn is whether or
> >> not the cold running enrichment is put on a duty cycle by the OX sensor
> >> control module, which sends the signals to the control pressure regulator.
> >> If it is, I believe that I can beat it by doing my own timed cycle, which
> >> would reset the systems' duty cycle.  Well, I don't even know if it's 
> >> going to be a problem yet.  I can you this though, the TT module doesn't
> >> address it if it is an issue. 
> 
> The differential pressure regulator( I think thats the one you're talking
> about) is controlled by a current, and you don't switch it off/on, but
> rather give it varying current levels, in the mA range.

Yes, of course I know this is how it works, but that's not how the TT device
works, that's how the Autotech device works.  If you read the manual, you'll
also discover that that the control unit DOES go into an approximately 40
second duty cycle for enrichment under SOME circumstances.  I am going to
run some tests to find out if the way the TT module does the fuel enrichment
causes the control box to run this duty cycle or not. 

> I have some reverse
> engineered data on the Autotech device someone else wrote up a few years
> back. The Bentley I believe has some info as to what the current range is.
> I think it can go from 120+ mA in cold start mode to around 15-20 mA at
> full throttle to -40mA or so during closed throttle deceleration. 

This is approximately correct.

> Unfortunately, I have yet to posess either Autotechs or TT module, and so I
> can't completely disassemble one to see what they're doing.
>    Trying to rely on automotive journalists to explain how electronics work
> can be quite futile, and I don't know that I'd rely on their description to
> reverse engineer the device.

To be perfectly honest, there's only ONE piece of information that I needed
from the EC article, and that was was mA rating to the control module should
be feeding the regulator.  From this I can work backwards to the proper coolent
temperature sensor input.

>  I designed a fuel enrichment device for the
> motorcycle market, and explained several times exactly how it works to both
> people at work, as well as journalists, and whoever asked. But when I saw
> an article describing the product, the description was so far off, I was
> amazed. The journalists were getting their description of the products from
> marketing people, both of whom felt they should modify my accurate
> description of how the thing worked. But since neither had a clue about
> electronics, the resulting product description had the product wired into
> the wrong sensors, reading the wrong signals, and calculating the
> enrichment incorrectly.

The EC article on the TT device is correct in describing how to wire up the
enrichment module.  

>   The document I have detailing the reverse engineering of the Autotech
> module appears to be written by someone who knows electronics, and from it
> it appears that the Autotech module simply modified the DPR current at full
> throttle. 

I believe that the Autotech device will modify the control current to the
regulator at different RPMS, and not just under full throttle, at least that's
what their write up on their web page implies.  They make a big deal out
of their RPM sensing capabilities.

> It did it in a very simple way. I had some ideas on how to
> improve the design, I've just got too many electronics projects going on at
> work to start up another one at home. But basically, instead of going to a
> fixed enrichment current like the Autotech module, just add an adjustable
> current source in parallel with the DPR wiring. 

You don't really want to do this, because you have no way of checking the
fuel/air ratio.  That's why the mA rating from the EC article is so important.

> 
> Brad
> >> 
> >> I may just publish the specifications on my web site, whenever THAT becomes
> >> a reality.
> 
>   If you have specs, feel free to email them to me, I'll add them to the
> other info files I have on my site.
> 
> Brad
> 

Sure thing!

==Brett
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