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Old 02-13-2005, 01:12 PM
A264172 A264172 is offline
Ta ra ra boom de ay
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Originally Posted by Duke2.6
Connect the VOM to the O2 sensor output - pull the connector apart just enough to get the probe in without disconnecting O2 sensor from the circuit. A VOM should measure about 450 mV. If you can test the O2 sensor with a scope, it will show the wave form and the output should jump back and forth between about about 0.2 and 0.8 volts a couple of times per second. This is the best test for O2 sensor health. Also test the O2 sensor heater, which is the two wire connector. Check for system voltage on the harness end, and continuity on the 02 sensor pigtail.

Your high CO readings indicate a rich mixture, so the Lamda system is probabably not functioning properly. A common culprit is a faulty O2 sensor. The Lamda engine temperature sensor could also be fauly - sending a false low temperature signal, so the system always thinks the engine is cold, or it could be the EHA or control unit problems.

Got 14.xV from heater connection (Brown=ground)
I got a reading (by puncturing sensor side of black wire to ground) of 0.451V at start up (coolant temp 80C) slowly (over 20-25min) descending to 0.349V.
Increase of rpm to 2500 would raise reading to about 0.360V at bottom end of the reading.
That and this...
Originally Posted by A264172
1) at X11 (ignition on engine off)
pin 3 red banana to V/F/C/Ώ/mA/uA
pin 2 black banana to COM
Dial set to % duty
reading 30.1
are leading me to coolant Temp sensor...

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:

Last edited by A264172; 02-13-2005 at 01:30 PM.
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