Re: 87 16V running rough
- From: David Craig <britton101@xxxxxxxxx>
- Date: Fri, 02 Jun 2006 22:41:12 GMT
Theo and Blah,
Thank you so very much for your input. I value each posting and will
put your advice to good use.
Thank you again,
Dave
On Fri, 2 Jun 2006 19:23:56 +0000 (UTC), blah <blah@xxxxxxxx> wrote:
Theo <grideout@xxxxxxxxxxx> wrote:
87 16V running roughOn my '89, I've had lots of O2 sensor issues. Mine
used to run a bit rich on startup, then would lean out after warm up. I
had a cracked downpipe, and I don't know if that affected things by
allowing a blast of outside air to come in. Anyway, I finally addressed
the problem when, during very wet weather or snow, the car wouldn't rev
up over idle. I resoldered the wires and heat-shrinked the connection
and that helped the major problem. If a little water gets in there, it
will never get out.
If you have to do this, make sure to stagger the cuts and as Theo said,
use heatshrink, not electrical tape. Cracked exhausts have a habit of
making O2 sensors read incorrect values, so make sure the exhaust is in
good shape before assuming a problem is related to the O2 sensor. Also,
the O2 sensor will have no impact on the performance of the car for the
first 90 seconds or so of operation.
On mine there's an electrical connection near the firewall, under the
hood, on the passengers side, from the oxygen sensor. I used to unplug
that when the car was running too rough to drive, and the car would then
smooth out because the shorted out oxygen sensor was out of the loop.
You could try unplugging the O2 sensor at that location and see if,
after a few seconds, it smooths out. If so, you know where the problem
originates.
Contrary to many peoples' beliefs, unplugging the oxygen sensor will not
cause it to go into limp home mode, it will simply ignore the oxygen
sensor. So Theo is correct, you can always try unplugging the O2 sensor.
Another time I had rough idle, and I did all the differential pressure
regulator current tests etc., and everything was fine. I then cleaned
the round shiny air intake plate. It was sticking (it should lift up
easily and Germanically smoothly) until I cleaned some oil and gunk off
it. That helped a great deal. That plate is discussed in the Bentley
manual. For some reason I'm blacking out on the exact way to access
it, or what it's called... I'll get back to you.
There's a rubber boot with a large hose clamp, just loosen the hose clamp
and remove the boot. Lift the plate with a magnetic pick-up tool. It
should move easily and smoothly. If not, clean it, if it still doesn't,
try to fix it, but most likely you are looking at getting a new (used) one
-- you don't want to know how much they cost new.
There's always the dreaded idle air stabilizer valve... someone once
told me to tap it with a hammer to see if that clears up rough idle, but
it never seemed to.
It amazes me how much people like to blame the idle stabalizer valve for
all their maladies. I'm not saying they never have problems, but I think
its heavily misdiagnosed. If you suspect the idle stabalizer valve, first
thing to do is unplug it and see what happens. If there is no real change
then its probably not the ISV. If there is, remove the ISV and clean it,
then try again. The flapper should move easily, and when released from
an open position return to an almost shut position. If nothing has
changed, the first thing to do is suspect an air leak. Primary air leak
sources are the fuel injector seals, and any vacuum lines or rubber
boots. All lines and boots must be crack free, and tightly sealed. Loose
hose clamps are unacceptable. Try spraying ether (car starting fluid)
anywhere that is suspect. Also try squeezing rubber boots. If the idle
changes, even slightly as a reaction to any of this, there is a leak. An
air leak can easily cause a perfectly functioning ISV to create a
hideously unstable idle.
As others have said, the coolant temp and thermo-time switches could
cause rich running. Disconnect the wires to those things and check the
connections and wires. I recently had to re-solder the wires to the
coolant temp sensor. Corrosion and heat damage to insulation are
common. Bad CTS wires or sensor itself, on my car, caused very
difficult cold starts, but did not affect running once the car was
started and warmed up.
On CIS-E cars the thermotime switch is *ONLY* used to aid in starting the
car when cold. The operative word here is "STARTING". Once the you are
no longer cranking the start, the thermotime switch is completely out of
the picture. In order to have a failed thermotime switch affect a car
while running, you would also have to have a faulty ignition switch and
wiring simultaneously. A faulty CTS could absolutely cause problems. Its
just a resistor with a temperature coefficient, so its trivial to test
(just measure the resistance when warm and cold and compare to the chart
in the Bentley.
.
- References:
- 87 16V running rough
- From: Wayne Faas
- Re: 87 16V running rough
- From: Theo
- Re: 87 16V running rough
- From: blah
- 87 16V running rough
- Prev by Date: Re: Older car insurance
- Next by Date: Re: 1987 Cabriolet
- Previous by thread: Re: 87 16V running rough
- Next by thread: Re: Cabrio parts
- Index(es):
Relevant Pages
|
Loading
