NetNews Usenet Archive 1992 #23/NN_1992_23.iso/spool/rec/autos/tech/14119

Internet Message Format | 1992-10-16 | 3.0 KB

Path: sparky!uunet!charon.amdahl.com!amdahl!rtech!pacbell.com!tandem!hood!bill
From: [e-mail] (Bill Norcott)
Newsgroups: rec.autos.tech
Subject: Re: Ford Tempo '86 problem
Message-ID: <[e-mail]>
Date: 16 Oct 92 18:04:05 GMT
References: <[e-mail]> <[e-mail]>
Sender: [e-mail]
Reply-To: [e-mail] (Bill Norcott)
Organization: Tandem Computers, Inc.
Lines: 45
Nntp-Posting-Host: hood.tsg.tandem.com

In article <[e-mail]>, [e-mail] (Bill Norcott) writes:
|> In article <[e-mail]>, [e-mail] writes:
|> |>
|> |>    This car has a EFI system .  Two years ago it had the controler
|> |>   computer replaced (the car was recalled by the dealer).
|> |>     Now the car has a (I believe) related problem.  When the engine
|> |>  is cold the car runs OK.  After driving for about 15-20 minutes,
|> |>  when the engine warms-up, the engine runs irregularly and then
|> |>  it stalls.  After that I have to restart the engine at every stop.
|>
|> Sounds like the oxygen sensor may be going or gone.  It is what
|> controls the fuel/air mixture to the injector once the engine has
|> warmed up and has gone from open loop (idle mode) to closed loop
|> operation.  I have an '87 Topaz with the same engine.  I am thinking
|> about changing my oxygen sensor.  I was having similar problems
|> before with the drivability when warm but fixed it by setting the
|> idle air speed adjustment screw to make it richer.  But this means
|> that when cold you have to hold down the gas for a minute after a
|> cold start.  The poor power on hills & stalling points to a too lean
|> mixture, so the O2 sensor may be bad.
|>

To follow up, I replaced the oxygen sensor on my Topaz yesterday at
~83,000 miles.   Following this I re-adjusted the idle speed
adjustment screw so the car again starts on the first turn of the
key and no longer stalls -- this let more air in but leaned-out the
mixture when the car warms up.  Previously, I had seen erratic idle
and loss of power when the car warmed up.   With the new O2 sensor
the problem is completely fixed, i.e. the cold starts are perfect,
and the warm-engine driveability problems have vanished.  For the
first time in the year I've owned it, the cold starts and warm
engine driveability are perfect.  It also solves a mystery which I
was unable to completely diagnose until I read the ongoing thread
about oxygen sensors.  On Fords, the sensor has a LOT to do with
engine performance but it the engine CPU does not detect its failure,
i.e. no engine codes for it.  It was a pain in the neck to get to
though, I had to raise up the car on ramps to get at the thing and
jam my hand in there to get at it.

--
---------------------------------------------------------------------|
Bill Norcott            GUARDIAN POSIX project
Tandem Computers, Inc.
10600 N. Tantau Avenue        PHONE:  [phone]
Cupertino, CA   95014        EMAIL: [e-mail]