Crank Sensor/Cam sensor

[John W. Stewart]

Bill,

Though GM used both crank and cam sensors in 1996 to control timing, I doubt
that the lack of a crank sensor will cause this problem. If the cam sensor
was bad, you would have erratic running on all cylinders, not just one bank.

Since we have no way to know how Howell programmed ECU, it's tough to
detrmine if that is the  problem. If the car runs fine when cold, and only
runs intermittently rich on one bank during closed loop, your most likely
culprit is a bad O2 sensor ( not likely, since a code would have been set)
or an intermittent connection in the wiring from the sensor to the ECU .
Intermittent problems ( whether high or low resistance causing a change in
the voltage reading the ECU sees) may not set a code because the duration is
to short. If this was the case, you would see the problem you describe, the
ECU would lean out that side and set the code for too lean a mixture.

As mentioned , you could switch sensors from side to side to see if the
problem switches sides. My feeling is the wiring on connectors. Get the VOM
out and check the resistances for the O2 wires on the good side, and do the
same on the bad side. Providing the wiring lengths are not too dissimilar,
they should be close. If one is way off,  you know the problem is in the
wiring or the connector(s). While you're at it, wiggle the connector pins to
see if the values change, if they do, you've found the problem.

John S.
----- Original Message -----
From: <Onebil2mny at aol.com>
To: <diy_efi at diy-efi.org>
Sent: Saturday, July 07, 2001 8:41 AM
Subject: Crank Sensor/Cam sensor


> I have a question concerning the GM ECM# 18188021...  According to the GM
> manual I am using, both the crank sensor and the cam sensor are used to
> determine #1 tdc and thus to calculate the computer will calculate the
> correct sequence with a 1 in 6 chance of getting it wrong. Could the lack
of
> a crank sensor coupled with a bad cam sensor cause this rich on one bank
> problem I am experiencing? It is a seemingly random condition.
>
> Thanks!
> Bill K
> --------------------------------------------------------------------------
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