Cat converter question

[NEGeorgia]

Hey guys,
Interesting forum lots of great info.
1994 Ford Ranger 4.0
I was wondering if a converter would cause a repeated code 137 ? (HEGO sensor rich)
I got that code KOER --
I have replaced both O2 sensors and MAF.
The MAF fault was repaired with MAF replacement.
I was reading some older posts on this sight and found a scenario that is just about the same as my concern , it suggests that the ECM is the culprit..
I have always seen and experienced that a ECM won't tell on its self.
The cat converter rattles some if you hit it with a dead blow hammer and was wondering if it could cause an inaccurate 02 reading.
Maybe i am thinking to deep.
Thanks guys for any input.

 

[arco777]

A bad converter alone won't usually throw a code, but it should not be rattling - it has probably fallen in and needs replacement. You may be able to get away with a universal fit unit. I installed one on a Firebird a while back made by Magnaflow and it worked great for a low price.

Converter rattle pretty much always indicates damage, but when you get a new one - don't hit it with a hammer

PCM failure is rare. I doubt that is your problem.

Something is probably causing your engine to run rich. Have you made any changes to it lately?

 

[NEGeorgia]

It started to run bad and light came on.
After I replaced both O2sensors it seems to run better but after 10 miles the check eng light came back on with code 137 koer.
I have checked the wiring from o2 vehicle conector back to ECM and it checks good.
I need to find out info about looking at Ecu input and output @ecm when running to what is going on ( live data )
Thanks

I have cleaned TB
Plugs & wires
Both o2 sensors
Replaced MAF for code 159 - that code is gone now

 

[MrShorty]

I need to find out info about looking at Ecu input and output @ecm when running to what is going on ( live data )

You might review Glacier991's "primer on code readers and scanners" thread in the computer control forum. http://www.explorerforum.com/forums/showthread.php?t=80707

You seem focused on the computer/sensor/electrical side of things in diagnosing this. Remember that other things (in particular problems in fuel delivery) can contribute to these conditions. One thing I might do in this situation is pull some spark plugs on the offending side and see what they look like. If they look sooty or otherwise also indicate that it is running rich, then the computer side of things is probably doing just fine. If the spark plugs look more like it is running lean (false rich indicated), then I would look further into the computer side of the problem.

 

[NEGeorgia]

Thanks Mrshorty,
I have read a lot of your posts and you seem versed in drivability issues.
I will pull the plugs and check that..
Thanks for your input.

 

[NEGeorgia]

Ok so I pulled the plugs and inspected.
Due to the fact that they are new and not many miles were put on them -- they look good,
No black.
The 137 code keeps coming back and sometimes the MAF code koeo & Koer.
The funny thing about it is sometimes it will run great and other times when pushing the gas you can feel a surge and no power increase when applying gas.
Anyone have a wiring schematic ?
I would like to check signal return back to ECM from the MAF and the drivers side o2 sensor. Brake out box would be nice.
I have checked sensor grounds.
Can an ECU be temperamental and cause this condition ???

 

[arco777]

Here is the EEC diagram I have for a 94 Ranger 4.0L. This is different from a 94 Explorer.

 

[arco777]

Here's the pinout of the connector for the PCM on a 94 Ranger 4.0L. This is different from a 94 Explorer.

Note that this is a view of the connector, not the PCM pins. To orient yourself, the easiest way I found was to reference the slant of the pins and locations of the empty ones. I believe there are also tiny pin numbers somewhere on the connector.

 

[NEGeorgia]

Thanks Arco777 that's just what I was looking for.

 

[NEGeorgia]

Update :
After getting wiring schematic from arco777 I proceeded to check wiring from sensors to ECU. Wiring good.
I pulled the ECU from its mounting and had to open it up and look inside to see if anything on the board was burnt. Sure enough there was a burnt diode , so I traced out the circuit on the board and it went to the o2 sensor pin at Ecu.
I sent the ECU out to blue streak to have repaired ($106.00) and installed back in truck.
Truck runs great now and no CEL on.
Thanks for your help Arco 777 and Mrshorty .

 

[arco777]

Thanks for the follow up! It will help others. Glad you got it resolved.

 

[mr cribb]

A bad converter alone won't usually throw a code, but it should not be rattling - it has probably fallen in and needs replacement.
Converter rattle pretty much always indicates damage, but when you get a new one - don't hit it with a hammer

Guess I need to replace my cat, it rattles like crazy. Thanks for the tip Arco.

 

[mazda1949]

94 ranger loss of power code 137

Update :
After getting wiring schematic from arco777 I proceeded to check wiring from sensors to ECU. Wiring good.
I pulled the ECU from its mounting and had to open it up and look inside to see if anything on the board was burnt. Sure enough there was a burnt diode , so I traced out the circuit on the board and it went to the o2 sensor pin at Ecu.
I sent the ECU out to blue streak to have repaired ($106.00) and installed back in truck.
Truck runs great now and no CEL on.
Thanks for your help Arco 777 and Mrshorty .

I just got through chasing one doing the same thing, code 137 and no power after it warmed up. pulled the ECM and had 2 bad capacitors. Fixed it myself thanks to this forum and Radio shack!!!