more on code 2141

[Bernard Littau]

> Hey guys,
>   Thanks for the advice. I checked the O2 sensor today by way of the male
> connector and got 4.5 ohms. I did the test with the engine off and cold.
> Is my
> O2 sensor good? More on the symptoms: it surges and the engine light comes
> on
> at low RPM under load. Boost doesn't feel nearly as urgent, but I still
> get
> 1.8 bar. Still gettin only code 2141.

Hi Jason,

Your check engine light coming on and the 2141 code are very unlikely to
have anything to do with your O2 sensor.

A resistance test is not really helpful with the O2 sensor.  Best is an
oscilloscope, but a fast volt meter will suffice.  See:
http://www.sjmautotechnik.com/cis_waveform.html
at the bottom for a typical O2 sensor waveform.

Basically, at idle, hot, the O2 sensor should hover around 0.5 volts, but
should be fluctuating.  A steady reading would be a sign of a problem, even
if it were 0.5 volts steady.  See:
http://www.sjmautotechnik.com/injector.html#osens

Your ECU is telling you that the engine is running too lean and is knocking.
It claims the knock will not go away with full retard (code 2141).  The
check engine light illuminating while driving means the ECU cannot regulate
the system to be within safe parameters.

Do the fuel volume and fuel pressure tests.  See:
http://www.sjmautotechnik.com/ficis.html#fuelp

Another possibility might be your intake temperature sensor.  I had the
check engine light illuminate while driving several years ago when I first
got the 5ktq.  I don't recollect what codes the ECU was throwing, so I don't
know if your situation is the same.  In my case, the intake temperature
sensor connection was intermittent.  When the temperature sensor connection
went disconnected (resistance is infinite), it looked to the ECU like way,
way, hot air, so it tried to compensate by retarding the timing.  I had the
check engine light illuminating anytime I went above 0.8 bar.  My car had a
replaced intake temperature sensor -- I could tell by the yellow wrecking
yard paint on the sensor, and by the amateur solder joint where the sensor
was attached to the harness.  You might inspect the harness leading to the
intake temperature sensor, which is mounted into the intercooler near the
intercooler output to the intake manifold.
See:
http://www.sjmautotechnik.com/10vcoolt.html#airt

Yes, it might be a bad knock sensor.  See:
http://www.sjmautotechnik.com/10vknock.html

See:
http://www.sjmautotechnik.com/support.htm
I have no affiliation with Scott, but his web site has not only saved me
$$$, but has also made the difference between owning a well running 5ktq and
junking it.

Best,

Bernard Littau
Woodinville, WA
'88 5ktq