Ke-Jetronic theory.(explained)

[brianm@earendel.org (brianm@earendel.org)]

Thanks for the input AL.

The useful things that we've gained out of this.
Remapping the ignition for a KE-jetronic car is easy.
basically if you want the normal inputs to still function startup, idle 
etc, knock retardation it can. we can just add on.

The FPGA board + some I/O chips will allow us to do anything we want to 
the ignition including having an RPM based changeover. its simply not a 
big deal with our cars.

Al. Thanks for the input together we'll get this down pat.

On Sun, 26 Jan 2003, Allyn wrote:

> > Well the thermotime switch turns on the 5th injector if the temperature of
> > the engine block is below a certain temp ( ce-efficient of linear
> > expansion switch, and if there is fuel flowing thru it. ( I believe,  this
> > is a odd little detail, it just normally effects starting. )
> 
> this works kinda like the blinker bulb in your christmass lights. if its
> cold enough, a temp sensitive contact closes. when current goes through the
> contact, it heats it to some degree, causing it to open. related to cis-e,
> the thermo-time switch contains the contact which carries current to the
> cold start valve. if its cold enough, the contact is closed, and goes
> through a cycle of opening/closing as it heats/cools during cranking
> (switching the cold start valve on/off like the christmass lights are). the
> colder it gets, the longer it takes to heat up the switch contact, resulting
> in longer pulse width in colder temperatures.

The the documentation didnt reference if there was a pressure or flow 
switch in the thermotime to make sure that if you werent cranking or 
running the 5th injector was on or off.

> 
> > It is prolly an IGBT,
> > but that depends on when your car was made it could be a PNP transistor.
> 
> high power switching mosfets. newer units may use igbt, but that technology
> wasnt cost effective when out cars were built.

Bosch references 3 types. I remember 2: a high power PNP setup,and an IGBT 
setup. not MOSFETs. My guess is the large return spike would short them 
out.
 >
 
> > (depending on your
> > car -- 16v dont have 3 wire O2 sensors, 8v's do).
> 
> every 16v i've had uses a 3-wire, as well as digifant 8v's

I just eyeballed the GRM car it only had 1 but it has a TT race down on 
it...My mistake.

> 
> > If it needs to adjust it, it changes the rate of the frequency
> > valve on your airflow plate buzzes at.
> 
> this is for 8v, isnt it? 16v's dont have frequency valves. for 16v it varies
> the DPR current, which is DC and has no frequency. varying DPR current
> affects internal control pressure, effectively changing the 'gain' of fuel
> output vs. air flow sensor plate position (in the end, changine mixture).

same idea different valve type. I've just been working on the bunny ... 
forever. The documentation is a little vague on some of this stuff. Please 
remember that this research comes mostly from the web and im missing my 
16v bently. any body got a loaner spare?

> 
> > It also adjusts the idle with the
> > idle stabilization valve. Im not sure how, but it has to do with how air
> > get recirculated.
> 
> yup, it bypasses the throttle valve. as for how, it varies the pulse width
> of an ~400 hz square wave going to the ISV. the valve inside the ISV cannot
> physically move that fast, so it sits at the average voltage present. longer
> pulse width leads to higher average, opening the valve further.
> 
> Al
> 

-- 
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Brian 
88 16v $2003 GRM challenge car http://www.grmotorsports.com
84 0v Next years car got parts?
82 2.0L Topless bunny -- Knock Ignition and bigger clutch. next.
90 90q20v doing daily driver duty. 
91 VFR750F everybody needs a 11-12 sec vehicle.

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