Recap of the SAI circuit

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12-20-2011, 11:40 AM

#421

ilko

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Quick question - will this help against a CEL with a cat bypass, or does the ECU register it as a separate system altogether?

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12-20-2011, 12:59 PM

#422

Lorenfb

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".13 - .09mV with the SAI pump running"

So it's possible that 0.0 volts could be problematic, as it may be too low
of a voltage. The key is reports from '97/'98 owners.

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12-20-2011, 01:48 PM

#423

Slow Guy

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Quote:

Originally Posted by Lorenfb

Right, but it won't tell you whether the DME ECM accepted the voltages
and passed the SAI test. Remember, the way the 993 OBDII monitor
system functions is that all the monitor tests must complete before any
tests will be indicated when reading the monitor tests via an OBDII
scanner.

From my experience it's a 3 then 5 scenario on my '97 993. (previous '97 993 too)

Will link to a previous post on this asap.

This thread

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12-21-2011, 12:17 PM

#424

Lorenfb

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"From my experience it's a 3 then 5 scenario on my '97 993."

Right, the first three are basically inconsequential, i.e. they basically never
have a problem getting set. The other five are the key ones that are
all emissions related and never appear to an OBDII scan until ALL successfully
complete not like USA OBDII vehicles and later Porsches, e.g. 996/997 that
show individually as completed.

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12-22-2011, 10:52 AM

#425

ltc

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Quote:

Originally Posted by Lorenfb

".13 - .09mV with the SAI pump running"

So it's possible that 0.0 volts could be problematic, as it may be too low
of a voltage. The key is reports from '97/'98 owners.

90 to 130 microvolts is pretty damned close to zero volts, so I don't believe your statement is valid in the context of this discussion.

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12-22-2011, 12:01 PM

#426

Lorenfb

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".13 - .09mV with the SAI pump running"

My error in not seeing the mv. Is it really mv? If that's the case, that brings
into question whether an accurate reading from the tester used has any validity
in what the actual value really is, as most/all live data values are only accurate
in the mv range and not in the microvolt range. The key, as mentioned
before, is to have someone/many with '97/'98 vehicles provide feedback.

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12-23-2011, 02:42 AM

#427

william_b_noble

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Interseting - still no posts saying that it works. surely someone has installed this thing.

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12-27-2011, 10:29 AM

#428

rc16

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Quote:

Originally Posted by ltc

90 to 130 microvolts is pretty damned close to zero volts, so I don't believe your statement is valid in the context of this discussion.

I believe there an error in the oxygen sensor voltages mentioned. It should read V and not mV. A voltage output of .2 V correspond to a lean mixture, a reading of .8 V is rich and around .5 V indicates a good running mixture.
rc16

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12-27-2011, 01:47 PM

#429

C4S993

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Please add me down for ONE completed unit.

Patrick
170k miles 1996 C4S
Full engine rebuild 22k miles ago and now SAI light back on.

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01-01-2012, 07:32 PM

#430

rdevany

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I measured 0.000V to 0.014V with clean ports and SAI pump running (pins 3 and 4 on left side sensor before the cat). Oscillation of the voltage above 0.000 began about 15 seconds after start. The pump stopped at 1 minute and voltages then rised rapidly to levels above 0.1V.

These results suggest that the DME could be monitoring these low voltages..i.e., the oscillations suggest that mixture adjustments are being made by the DME (the other 3 O2 sensors were operational in my test), and the upper range of the measurements are within 10% the known DME voltage monitoring range (i.e., 0.1 to 0.9 V).

Based on these results, I concur that more data is needed....i.e., either the actual SAI flag code contained in the DME or more results from installation of the test circuit.

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01-01-2012, 10:22 PM

#431

Ash

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Added: added C4S993

Added (by Lewis): latest additions to 2nd Round List (via PM request): jgingera, maestromaestro, ptsheridan

This list for the first round of boards is now closed. I've started a Waiting/Back-up list below for those that missed this first run.

Quick reminders:
1) unless otherwise noted, it's assumed you are asking for an assembled unit.
2) enclosures are optional - feel free to update/ Post a reply/ PM and I'll update the list if you are looking for an enclosure.

Payment Info posted by Lewis (from post #147):
Once assembled, I will start sending PM's so folks can provide me their shipping addresses. Inside the package will be the unit, a hardcopy of the schematic, a hardcopy of the PCB layout and a return address envelope. When you get the unit and everything is OK, just use the envelope to send payment. I am a trusting person when it comes to RL members, so I have no problem sending out the units prior to receiving payment.