ION Project Papers & Info Sources

[garfield at pilgrimhouse.com]

On Sat, 9 May 1998 11:26:30 +0300, "Joachim M. Wagner"
<1028-156 at online.de> wrote:

>What influence does this ion sensor
>have on the e.f.i. or ignition system?? And what are the output signals
>created from ECU given to the engine???

Eh? You musta just joined the thread. This has been discussed
previously, so I'll just give ya a summary, and you can crawl up the
thread for more of the details.

The ionization sensing gives two basic things to the ECU. One is signals
to tell it if a jug fired or not (which they use instead of a cam
sensor, and also for misfire detection). The second input to the ECU is
an analog signal (is read by an A/D in the ECU) representing the actual
analog ionization current, which they scan with the A/D to detect things
like knock. This information is used to modify spark advance, boost
limits, and even enrichment (enrichment is tried if backing off on adv &
boost alone doesn't do the trick, according to the Saab manual).

There are no special inputs TO this IGN signal from the ECU, other than
the normal ones to tell the plugs to fire. So it's basically a simple
CDI system, with special sensor technology using the plugs, to return
correct plug firing, and detonation/pre-ignition info to the ECU. That's
it in a nutshell.

Anything very clever done to the analog Ionization current is being done
INSIDE the ECU by the cpu, once the A/D is read.

Gar