90 Ford Escort 1.9 EFI - KOEO and KOER Codes

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?
Thanks! Matt
KOEO: 41, 65, 86 KOER: 47, 16
Descriptions from the Actron code manual:
KOEO 41: EGO sensor: voltage signal always "lean" (low value) - does not switch
KOEO 65: Electrical charging system problem occured - voltage too high (over 17.5), or 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
KOEO 86: 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 failure
KOER 47: 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
KOER 16: 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)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dang, ain't nothing simple? Never would have thought of fuel pressure, just assumed that the EGO sensor went bad. Not sure how fuel pressure factors in, however.
Thanks, Matt

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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, Matt

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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?
Thanks, Matt

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@hotmail.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 helps.
Thanks, Matt
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Snip.

the regulator and pump.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.
Thanks, Matt
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

For example Tempo/Topaz the fuel pressure engine running is a minimum of 45 psi. Most information given from testers, do not go into detail for each vehicle you can test with it.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.
Thanks, Matt
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@hotmail.com (Matt) wrote in message

Whoops, I read that thermactor thing wrong, looks like the exhaust pulls air into the air box.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@hotmail.com (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?
Thanks, Matt
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Fuel pressure engine running should be 35 to 40 psi. Fuel pressure engine not running about 40. With the vacuum line to the regulator removed you should see close to 40.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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, Matt
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.