Post rebuild engine codes 44,47

3tbird

Registered User
I just had the S&S rebuilt long block installed....but now I have the following check engine codes; 41, 91, 44, 47

I've replaced both O2 senses and still pull the 41, 91 codes after clearing them twice.

Motor run hot on the "R" or "M" on the temp gauge.

The 44 is the 'Thermactor air system fault' .. anyone know what this relates to?

The 47 is the 'vane air flow too low'....again anyone know what this point too as well.

My first guess now is the injectors are weak.....because I have 36 lbs of fuel pressure at idle and 39 lbs under standing trottle jump. (new pump installed)

Please advise and thank you!
 
With out knowing the test you did for the codes I'll post them for you.

41 = Exhaust Gas Oxygen (EGO) sensor: voltage signal always "lean" (low value) - does not switch.

Exhaust Gas Oxygen sensor
The EGO sensor is threaded into the exhaust manifold, directy into the stream of the exhaust gases. The ECA uses the sensor to "fine tune" fuel delivery. The sensor generates a voltage of 0.6 to 1.1 volts when the exhaust gas is rich (low oxygen content). The voltage changes to 0.4 volts or less when the exhaust gas is lean (high oxygen content). The sensor only operates after it reaches a temperature of 660 degrees F / 349 C

44 = Problem in Themactor Air Control system.

Thermactor Air System
An emission control system coof an air pump, air flow control valves (TAB & TAD) and a catalytic converter. The converter removes pollutants from the exhaust stream. An air pump brings outside air (when needed) and sends it either to the exhaust manifold ("upstream") or directly into the converter ("downstream"). The ECA controls the air path for best performance under different engine operating conditions. The air pump always runs when the engine runs. Usually the incoming air is directed to the converter. Air is kept out during extended iding (prevent converter overheat) or during very cold engine starting. Air goes into the exhaust manifold during normal engine warm-up. This helps burn hot, unused fuel vapors in the exhaust stream (reduces pollutants - speeds exhaust warm-up). The TAB and TAD valves may be separate units, or combined into one assembly.

AM-1
Air Management solenoid #1, also called TAB

TAB
Thermactor Air Bypass solenoid. (Sometimes called AM-1.) The ECA energizes this solenoid to apply vacuum (and thus activate) the TAB valve. Normally, this valve allows incoming air to pass into the rest of the system. When Actived, the valve takes the incoming air and dumps it back into the atmosphere. Refer to Thermactor Air System description for more details.

AM-2
Air Management solenoid #2, also called TAD

TAD
Thermactor Air Diverter solenoid. (Sometimes called AM-2.) The ECA energizes this solenoid to apply vacuum (and thus active) the TAD valve. Normally, this valve directs incoming air to the catalyticconverter. When activated, the valve takes the incoming air and directs it to the exhaust manifold.

ECA
Electronic Control Assembly. The "brains" of the engine control system. It is a computer housed in a metal box with a number of sensors and actuators connected with a wiring harness. Its job is to control fuel delivery, idle speed, spark advance timing and emission systems. The ECA receives infomation from sensors, than energizes various actuators to control the engine. Sometimes vehicles have additional computers controlling other functions. These include antilock brake and active suspension systems.

47 = Exhaust Gas Oxygen (EGO) sensor signal voltage indicates "rich" during "lean" air/fuel conditions.
or,
Vane Air Flow (VAF) sensor - voltage signal is low.
or,
Transaxle problem - 4X4L switch is closed

Vane Air Flow sensor
This sensor is a rotary type potentiometer connected to a moveable flap. It is located inside the vane meter assembly - a housing between the air cleaner and throttle body through which all incoming air passes. Flowing air pushes against the flap. The sensor sends a signal based on the flap position. The voltage signal increases when the flap moves because of increased incoming air flow. The ECA determines the amount of incoming air with this sensor. This infomation is used for control of fuel delivery, spark advance and EGR flow

91 = Exhaust Gas Oxygen (EGO) sensor - signal voltage always indicates "lean" either during Engine Run Self-test ("rich" air/fuel conditions) or normal engine operating conditions.
or,
Transaxle problem - Shift Solenoid 1 (SS1) circuit failure.

SS1
Shift Solenoid #1. Located in certain electronically controlled transmissions along with Shift Solenoid #2. The ECA energizes these solenoids (one or both) to engage the desired transmission gear.



Hope that helps,
ThunderSC
 
Last edited:
Outstanding info from ThunderSC

Thank you for the in-depth info!

I have an AUTO X-RAY unit that runs the KOEO and KOER testing.
Car was warmed up and idling fine.

I again scanned the FORD Shop manual and ran across the propane test - vacuum leak check. It denoted the 41/91 codes. The installer did use the rubber O-ring seals for the IC tubes but that doesn't mean they are set right. I have some seal tape to redo them if necessary.

Next step is the propane test....and anything else some-one can think of.


THANKS AGAIN, the help is appreciated!
 
I had the 41 and 91 codes on my car after the rebuild with new O2's

What vacuum are you running? should be around 20 inches with a stock engine.

Did you make sure you had the 3 wire O2's? I added Kooks Headers and used the Bosch number off the Website.

http://www.sccoa.com/faq/supplierpartnumberlisting.php?partnumber

Bosch 15717 and 15718 4 wire sensors that did not work and gave me the 41 and 91 code. Fit the connector...Doh


I should have used (lifted from the post below by blackthndr)

However, you can purchase
replacement 3-wire O2 sensors from Bosch that are longer. #13942-8.5” is the
part number for the stock sensor. #13950-13” are 13 inches long and #13953-
16.5” are 16.5 inches long. With Kooks/SCP short tube headers the 16 inch
sensors fit very well.


http://www.sccoa.com/forums/showthread.php?s=&threadid=12488
 
Reply

The propane test is using bottled propane like you'd use to sweat plumping...but no fire.

Do this in a VERY WELL ventalated place. You open the torch (no fire lit) and go around the injectors, IC tubes, IC and anyother intake locations. If the engine idle speeds up you've found a leak.

PS, warm the engine up first.

I have the 13942 bosch O2 sensors. These work fine on a stock engine with stock exhaust manifolds/down tube.
 
No vacuum leaks

Well I found not vacuum leaks and I'm pulling the 19 inches of vacuum warmed up at idle in gear (auto) 20 in netural.

ANY OTHER SUGGESTIONS TO CHECK?
 
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