I ran a scan on my car this morning. All of the descriptions have at
least one condition for an EGO fault or a fuel condition. I think I'm
going to replace the EGO, any thoughts?
KOEO: 41, 65, 86
KOER: 47, 16
Descriptions from the Actron code manual:
EGO sensor: voltage signal always "lean" (low value) - does not switch
Electrical charging system problem occured - voltage too high (over
Engine control system never went into closed loop fuel operation, or
Transaxle problem - Overdrive Cancel Switch (OCS) was not cycled
during engine run self-test
Transaxle problem - 3/4 shift solenoid circuit failure, or
Electronic Control Assembly (ECA) status - adaptive "rich" limit
reached in fuel control program, or
Wide open throttle Air conditioner clutch (WAC) solenoid - circuit
Exhaust Gas Oxygen (EGO) sensor signal voltage indicates "rich" during
"lean" air/fuel conditions, or
Vane Air Flow (VAF) sensor - voltage signal is too low, or
Transaxle problem - 4x4L switch is closed
RPM too low during Engine Run Self-Test (lean fuel test), or
Idle Speed Control (ISC) RPM out of Self-Test specification, or
Electronic Distributorless Ignition System (EDIS) fault - Ignition
Diagnostic Monitor (IDM) signal not received, or
Exhaust Gas Oxygen (EGO) sensor - signal voltage indicates "rich"
during Engine Run Self-Test (lean air/fuel conditions)
It looks like too low fuel pressure. Before you go and replace parts, know why
you are replacing parts. Plugged fuel filter, bad fuel pressure regulator,
failing fuel pump, all can cause most of the codes.
The sensor only tells the processor what the oxygen level is in the exhaust. If
the fuel pressure is too high or low, the exhaust will have too much or too low
oxygen content in it. So the O2 sensor will read accordingly. Yes there is the
possibility of a bad O2, but instead of guessing and spending money needlessly,
maybe you ought to read up on how the system works. Then diagnose in an
intelligent fashion and replace or repair what is broke. And yes, it is simple,
unless you do not understand the system.
Thanks for the info. No money spent on parts yet, still following
leads to determine the exact problem, as you suggested. Picked up a
fuel pressure tester, instead. As much as fixing the problem, I also
like to tinker, which one reason why I'm still driving a '90. Gives me
something to mess with about every six months.
145,000 and climbing,
Another symptom with this car, the idle has been running high for a
few weeks now, about 1500 RPMs when sitting at a light, etc., with no
pressure on the gas pedal. I took a look at what I think is the
throttle air bypass valve, what's on top of the fuel charging
assembly, air intake, etc., it has a wiring harness connected to what
looks like a solenoid. I thought maybe the high idle could be due to
too much air getting into the intake. When I unplugged the solenoid
from the wiring harness, the idle went back to normal (~1050 RPMs).
After about a minute the engine started choking, I think, with the
idle going down to about 500 RPMs, must be suffocating without any air
I thought. Plugged it back in and it went back to 1500 RPMs.
Could a bad throttle air bypass valve, if malfunctioning, cause both a
high idle and an EGO "always lean" condition if allowing too much air
into the engine? Could this explain the lean condition the EEC is
reporting, if too much oxygen was in the exhaust gasses, while also
raising the idle? Maybe the bypass valve is having an effect on the
EEC to cause a higher idle?
First off look at the code, what does it mean always lean? You are on the
correct track, too much air, or not enough fuel or both. What will give too much
air into the intake? Vacuum leaks, bad PCV valve. The Idle control solenoid
usually does not, but I suppose it can. On a speed density system ( what you
have ) any un-metered air ( intake leak ) will drive up the idle speed, the
larger the leak, the higher the speed. Will a malfunction of the by pass valve
cause high idle, sure can. It will also cause stalling due to not being able to
adjust idle when a load is put on the engine.
email@example.com (Matt) wrote in message
Ran another test, getting KOER 45. Checked the thermactor valve and
getting suction on the outlet (going towards the air box). I think
that's the outlet, because I thought the air is pulsed to the air box
using pressure from the exhaust.
No code 16 this time.
I checked the fuel pressure, reading at 32 psi. The manual says it
should be 39 psi, so definately low. It was time to replace the fuel
filter, so I tried that, but no help. Still 32 psi.
The manual says that the next step is to check for leaking fuel lines,
malfunctioning fuel pump, and leaking injectors. With a 1990 EFI
Escort, can anyone suggest anything else worth checking? Is there a
fuel pump filter as well, near the vicinity of the pump? Also, I have
one of those whiny fuel pumps, original from the factory, if that
The regulator on this car is vacuum actuated, so there should be a
pressure drop between 2 and 10 psi from the factory spec? At least
that's what the pressure tester literature says.
When I turn the ignition off the regulator does go up to about 40 psi.
Increasing the idle speed also drops the pressure from about 34 to
32, I guess that's the effect of the manifold vacuum?
Having the pressure regulator go would be a real bummer! I can't even
see the thing underneath the intake manifold.
I have the chilton and haynes manuals, but no details in either book
on pressure drop at idle, just specs fuel pressure at 39 psi (wish it
said ~35 at idle, would've saved me some head scratching). Having
poured through the manual looking for bits, I picked up the tester
literature on a whim, which is where I was tipped off about the
pressure drop (was a general comment regarding EFI engines). Some
google searching helped put together how the pressure regulator works
with the manifold pressure to manipulate the fuel pressure at
different engine speeds.
firstname.lastname@example.org (Matt) wrote in message
Just to clarify, with the engine running the fuel pressure is actually
hovering at about 34 psi. Shutting the engine off causes the fuel
pressure guage to climb up to about 40 psi. Not familiar with testing
fuel pressure, and looking for some thoughts on interpreting these
readings. Maybe the fuel presure is OK?
I'm going to check it again tomorrow and see how it goes with
unplugging the vacuum to the fuel pressure regulator. If It goes up
to 40 without vacuum, and running at about 34 with vacuum, maybe time
to move on to replacing the EGO sensor.
Thanks for the help,
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