MTX stall...O2 codes redux

[shorty]

In the original post 2 weeks ago I told the story of my ride home and how my car stalled; here are the codes I pulled at the time:

KOEO:
172: Oxygen sensor not switching - system is or was lean - Single, Right or Rear HO2S - Fuel control

176: Oxygen sensor not switching - system is or was lean Left or Front HO22SSS - Fuel control

542: Fuel pump open, bad ground or always on - - Power / Fuel Pump Circuits

KOER:
136: Oxygen sensor not switching/system lean Left or Front HO2S - Fuel control

159: MAF sensor is/was out of range - MAF

411: Idle speed system not controlling idle properly (generally idle too high) - ISC

______________

I recieved a lot of advice which I'm trying to implement, here are my initial results:

-CLEAR CODES-
KOEO: 111
KOEO stored: 512

-CLEAR CODES-
KOEO: 111
KOEO stored: 512
KOER: 225

-CLEAR CODES-
Drive car ~5 miles highway, ~5 miles city
KOEO: 114
KOEO stored: 111
KOER: 167, 225

Since 167 indicates I didn't give enough "goose" I re-ran the tests:

KOEO: 111
KOEO stored: 111
KOER: 111

Interesting that the 114 went away for the second test, not sure if that has any significance.

Of greater interest/concern is that the MAF and O2 codes didn't resurface. At this point the codes indicate no problems, but I haven't done anything to fix it. I still have the same fuel in the tank, but today was a lot cooler (40) than on the stall day (75-80).

I appreciate your input,
Rob

 

[Storm-Chaser]

DTC 114

Intake Air Temperature (IAT) / Engine Coolant Temperature (ECT) Sensors


Remember

To prevent the replacement of good components, be aware that the following non-EEC areas may be at fault:

• Coolant level
• Cooling system
• Cooling fan
• Water pump drive belt
• Engine operating temperature
• Engine oil level
• Thermostat
• Air cleaner duct
• Ambient air temperature

This Pinpoint Test is intended to diagnose only the following:

• Intake Air Temperature (IAT) sensor (12A697)
• Engine Coolant Temperature (ECT) sensor (12A648)
• Knock Sensor (12A699)
• Harness circuits: IAT, ECT, and SIG RTN
• Powertrain Control Module (PCM) (12A650)

Description
The Intake Air Temperature (IAT) and Engine Coolant Temperature (ECT) sensors change resistance in response
to temperature. IAT and ECT sensor resistance decreases as the surrounding temperature increases providing a
signal to the PCM indicating the temperature of the intake air or engine coolant.



DA1 |

DIAGNOSTIC TROUBLE CODE (DTC) 116 OR
114: CHECK OPERATION AND INSTALLATION OF
TEMPERATURE SENSOR​

__________________________________________

DTC 116 (ECT) or 114 (IAT) indicates the sensor
is out of Self-Test range. The correct range is 0.3
to 3.7 volts.

Possible causes:

- Low coolant level (ECT).
- Ambient temperature below 10° C (50° F)
(IAT).
- Damaged harness connector.
- Damaged sensor.
* Run engine for two minutes at 2000 rpm.
For NO STARTS:
- GO to |DA3|.
For vehicle STALLS
- GO to Pinpoint Test Step |S1|
* Check that the upper radiator hose is hot and
pressurized.
* Rerun Quick Test
* Is DTC 114 or 116 present?

YES > GO to |DA2|.

NO > SERVICE other DTCs as necessary.​

DA2 |

CHECK VREF CIRCUIT VOLTAGE AT THROTTLE
POSITION (TP) SENSOR​

__________________________________________

• Refer to schematic in Pinpoint Test |DH|.
• Key off.
• Disconnect TP sensor.
• Key on, engine off.
• Measure voltage between VREF circuit and
  SIG RTN circuit at the TP sensor vehicle
  harness connector.
• Is voltage between 4.0 and 6.0 volts?.
  
  
  YES > RECONNECT TP sensor. GO to |DA3|.
  
  NO > GO to Pinpoint Test Step |C1|.​

​

(To give you some idea as to the extent of some of these Pinpoint test procedures, this particular one goes to TEST STEP DA101 !!!)

 

[Mr Anonymous]

Ignore the 114 code, as any time the outside air temp is 50*F or below false 114 codes are possible.

You've already figured out that the 167 and 225 codes were just a result of the KOER procedures not being quite right the first time.

The 512 I wouldn't worry about right now, although it is a bit peculiar to see it.

Did you try cleaning your MAF filaments yet? I still think the MAF is the root of your problem. Going from an ~80*F day to a ~40*F day could have helped bring the fuel trims back to just within spec because of the change in air density. But, you also didn't really take the car on a long enough drive for the PCM to get an accurate picture of the long-term fueling.

If you haven't tried cleaning the MAF filaments yet I'd say try that and then take the car on a good 30 minute test drive in mixed highway/city conditions and see where that gets you.

 

[shorty]

I didn't clean the MAF yet, (but I bought the CRC stuff). My concern is that if I had cleaned the MAF the result of my last test would have indicated to me that I had fixed the problem since the codes went away. As you suggest, I would like to run a more extensive test (on a warmer day) and try to get the code to repeat. Since this will/could also bring about a stall, I need to pick the right time.

Rob

 

[Storm-Chaser]

Actually, the 512 DTC should be addressed first, as the PCED states to resolve the Continuous Memory (CM) faults before proceeding with the Key On Engine Running (KOER) faults.


So unless shorty has used a hand-held code reader that tells whether the other codes are CM codes or not, the PCED recommendation would be to start with DTC 512.

 

[Storm-Chaser]

DTC 512

Continuous Memory
Diagnostic Trouble Code
(DTC 512)


Remember

This Pinpoint Test is intended to diagnose only the following:

• Harness circuit: KAPWR
• Powertrain Control Module (PCM) (12A650)

Description
Not Applicable.



QB1 |

CHECK KAPWR TO POWERTRAIN CONTROL
MODULE (PCM)​

__________________________________________

Continuous Memory DTC 512 indicates the PCM
has experienced a power interrupt in its Keep
Alive Memory (KAM) circuit.

NOTE: If KAPWR is interrupted to the PCM, for
Example when installing a breakout box, or
when battery is disconnected, DTC 512 may be
stored in Continuous Memory.

• Key off.
• Disconnect Powertrain Control Module (PCM).
  Inspect for damaged or pushed out pins,
  corrosion, loose wires, etc. Service as
  necessary.
• Install breakout box, leave PCM disconnected.
• Measure voltage between Test Pin 1 and Test
  Pin 40 or 60 at the breakout box.
• While observing DVOM, grasp the EEC-IV
  harness and wiggle, shake or bend a small
  section while working from the PCM to the dash panel.
• Does DVOM indicate less than 10.5 volts?

YES >

SERVICE open circuit.
REMOVE breakout
Box. RECONNECT PCM.
RERUN Quick Test.​

NO >

RECONNECT PCM. GO
to |QB2|.​

QB2 |

INSPECT ENGINE COMPARTMENT WIRING FOR
PROPER ROUTING​

__________________________________________

• Inspect EEC wiring for closeness to ignition
  components or wires. If EEC wiring is close,
  reroute as necessary.
• Clear Continuous Memory DTC (refer to Quick
  Test Appendix, Section 5A).
• Wait 5 minutes to allow DTC 512 to reset.
• Rerun Key On Engine Off Self-Test.
• Is DTC 512 still present?

YES >

REPLACE PCM.
REMOVE breakout
box. RERUN Quick
Test.​

NO >

REMOVE breakout
box. RECONNECT
PCM. SERVICE other
DTCs as necessary. If
none, testing is
complete.​

 

[Storm-Chaser]

For others looking for background information, here are the reference threads:

Initial thread covering this issue:

95 MTX stall... O2 codes​

Previous problem:

Newbie with codes​

 

[Mr Anonymous]

Actually, the 512 DTC should be addressed first, as the PCED states to resolve the Continuous Memory (CM) faults before proceeding with the Key On Engine Running (KOER) faults.


So unless shorty has used a hand-held code reader that tells whether the other codes are CM codes or not, the PCED recommendation would be to start with DTC 512.

Working on these cars every day, I've found the PC/ED to be pretty much useless most of the time.

There are countless procedures in the various service publications which when compared to logical problem solving in the real world are completely nonsensical. Plus, most of the service procedures often specify the use of various specialty test fixtures such as a break-out-box which few if any SHO owners asking for help on this forum are going to have access to (never mind that Ford techs usually don't/won't use them even if they have access to them).

The bottom line is that the PC/ED, or any other service pub, isn't the be-all and end-all of SHO troubleshooting. Following it with blind faith can result in spending hours chasing a problem which either isn't a problem or can be resolved in 10 minutes using a little intuition and/or real world experience.

shorty, I'll reiterate my point from earlier: for the time being, you're best bet is to IGNORE the 512 code. When I've seen this code it has always been completely unrelated to any underlying issues, and while the diagnostic routines noted above are interesting they're really not going to do anything towards rectifying your stalling issue.

 

[shorty]

No code reader here, I used the paper clip self diagnostic a la "Phoenix Project".

I must admit that while I do have some engine experience it is primarily with older (read: "no dang computer") vehicles. I find chasing codes on the SHO interesting but frustrating. Probably because I'm shooting in the dark. Hopefully I will get the hang of it.

By the way, after checking some other threads I also check for vaccum leaks by spraying WD40 on the rubber intake connectors - no change in idle speed.

Other food for thought that occured to me after the discussion of possible connection issues: The previous owner mentioned having his mechanic replace the subframe bushings. Would this require pulling the engine or otherwise disconnecting much of the harness? The reason I ask is that portions of the harness appear to not be properly attached to clips etc.

Thanks for the input, I only get to work on this car on the weekends (if I'm lucky) and sometimes go for 2-3 weeks without being able to touch it (I work in one town, my garage is in another - this is not according to my master plan, but it is what I have right now).

Rob

 

[Storm-Chaser]

Shorty – spend some of that $100+ you saved and buy a good code reader. You can get the Innova Ford Code Reader (model #3145) from O’Reilly’s for $35.99 or Advance Auto for $29.99 and tax. You can even order a 6-ft extension cord that allows to operate the reader from inside your car....

Ford Code Reader at Advance Auto

Ford Code Reader at O’Reilly’s​

 

[shorty]

ok man, that's probably a good addition to my tool collection. Never bothered to check the price, just assumed it was more expensive. No SHO time this weekend; to busy de-winterizing Mrs Shorty's motorcycles. Thanks for the continued help, will update as appropriate.

 

[Mr Anonymous]

If you need a good code reader, I can send you a few paperclips.

It is a complete waste of money to buy ANY code reader for an EEC-IV car. I say this having access to an MT2500 and an NGS and never, ever, once have felt the need to use anything more than a paperclip to scan an EEC-IV car. There is nothing a scan tool/code reader, whether it's a $10 model or a $10000 model, can tell you that a $.0001 cent paperclip can't.

 

[Storm-Chaser]

And I'm sure *ALL* those paper clips come with readouts that will tell shorty whether he has a KOEO, KOER, or CM code.....

I didn't think so.................

That worthless $30 code reader does....

 

[Mr Anonymous]

And I'm sure *ALL* those paper clips come with readouts that will tell shorty whether he has a KOEO, KOER, or CM code.....

I didn't think so.................

That worthless $30 code reader does....

Let me guess, you've never actually used the paperclip method, right? :shakehead

There is absolutely no need for a readout, just a bit of common sense. If someone doesn't know whether they're running KOEO or KOER codes, they should just close the hood and call it a day.

Hard codes and memory codes come out in order, so it's quite easy to know which is which.

This isn't rocket science. Simplicity is key when it comes to these cars, trying to unnecessarily complicate things accomplishes nothing.

 

[Storm-Chaser]

In the original post 2 weeks ago....

Of greater interest/concern is that the MAF and O2 codes didn't resurface. At this point the codes indicate no problems, but I haven't done anything to fix it. I still have the same fuel in the tank, but today was a lot cooler (40) than on the stall day (75-80).

I appreciate your input,
Rob

So why did the prior Mass Air Flow (MAF) and Oxygen sensor (O2)(HEGO)(HO2S) codes not reappear?

As I previously stated, the previous code-set that included six fault codes, of which three were likely Continuous Memory (CM) codes. The 176 code was a CM code, the 172 code a CM code, and the 542 a CM or KOEO code. The three remaining codes (136, 159, 411) were KOER codes.

Continuous Memory faults are stored when a sensor/component fault/failure is sensed during normal vehicle operation. Intermittent Continuous Memory faults that have not reoccurred in the last 80 “warm-up” cycles (40 cycles in some applications) are erased by the PCM from the vehicle’s CM. Thus its entirely possible that one or even all three of those faults had occurred before shorty’s problem and are totally unrelated and/or no longer occurring. This is reinforced by the fact that none of the codes reappeared during his re-tests, but this does not eliminate the possibility that they were/are due to an intermittent condition that has not reappeared.


This is the primary reason I don't recommend pulling codes using a paper clip. The paper clip trick does not distinguish between retained CM codes and the KOEO and KOER codes generated during their respective tests - you’re only getting half the fault code information.

Why is it important to know whether the code is a CM, KOEO, or KOER fault? One, because in some instances different problems throw the same fault code, depending on whether the fault occurred as a prior condition stored in CM (some times referred to as a hard-fault), as a sensor out-of-range/fault/failure during the KOEO test, or as a sensor out-of-range/fault/failure during the KOER test. Two, because when the fault code is thrown helps determine what is causing the fault. For example, code 513 can be thrown and stored as any of the three (CM/KOEO/KOER). The testing procedure is the same regardless of “when” the code was thrown [set]. However, code 121 can also occur and be stored as any of the three (CM/KOEO/KOER), but the testing procedure is different for each of the three fault types (CM/KOEO/KOER), depending on when the code was thrown/set.


Of the three KOER codes, two common possible causes jump-out between the three DTC routines - wiring (VPWR) and the Powertrain Control Module (PCM).

I'll post the beginning of the DTC routines, where it becomes obvious.


How one chooses to work on their vehicle is entirely their decision. However for those with little experience trouble-shooting the SHO, the Diagnostic Routines will provide most with a methodical Yes/No means of testing the most probable causes at very little cost, versus potentially throwing money down-the-drain. Granted cleaning the MAF sensor has little cost, but you can only prove when it fails to correct the problem - there’s no measurable way to prove it has corrected the problem (or that the MAF was the problem). Measuring voltage output as per the troubleshooting routine will provide a measurable means to see if the sensor is out-of-range. Shorty then has the option of seeing whether cleaning the sensor will bring it back in range, or if it is malfunctioning to the point it should be replaced.

 

[Storm-Chaser]

DTC 172 / 176 / 136

Fuel Control


Remember

To prevent the replacement of good components, be aware that the following non-EEC areas may be at fault:

• Coolant level
• Ignition system
• Evaporative Emission (EVAP) System
• Positive Crankcase Ventilation System
• Secondary Air Injection System
• Exhaust Gas Recirculation System
• Air Intake System / Filter
• Fuel and Engine Oil Contamination
• Electrical System
• Fuel System (ie. Fuel Filter Pump Pressure)
• Intake Manifold, Supercharger, Charge Air Cooler
  Leaks
• Exhaust Manifold System Leak / Plugged
• Engine Cooling System
• Base Engine (ie. cam timing, compression)

This Pinpoint Test is intended to diagnose only the following:

• HO2S / Heater
• HO2S Connection
• Vacuum Systems
• HO2S Relay
• Fuel Injector
• Harness circuits: HO2S GND, HO2S,
  INJ. 1-8, VPWR, and SIG RTN
• Powertrain Control Module (PCM)

Description
The Heated Oxygen Sensor (HO2S) reacts with the oxygen in the exhaust gas and generates a voltage based
on this reaction. A low voltage indicates too much oxygen or a lean condition. A high voltage indicates not
enough oxygen or a rich condition. The fuel injector is a typical on/off device. The amount of fuel delivered is
determined by how long the injector is held open.

[deleted]

 

[Storm-Chaser]

DTC 159

Mass Air Flow (MAF) Sensor


Remember

To prevent the replacement of good components, be aware that the following non-EEC areas may be at fault:

• Coolant level
• Air cleaner element
• Inlet air duct
• Throttle body

This Pinpoint Test is intended to diagnose only the following:

• Mass Air Flow (MAF) sensor (12B597)
• Harness circuits: VPWR, PWR GND, MAF, and MAF RTN
• Powertrain Control Module (PCM) (12A650)

Description
The Mass Air Flow (MAF) sensor is located between the air cleaner and the throttle body. The MAF sensor uses
a hot wire sensing element to measure the amount of air entering the engine. Air passing over the hot wire causes
it to cool. The MAF sensor then outputs an analog voltage signal to the PCM to determine the intake air mass.
The PCM calculates the required fuel injector pulsewidth in order to provide the desired air / fuel ratio.

[deleted]

 

[Storm-Chaser]

DTC 411

Idle Air Control (IAC)
Solenoid


Remember

To prevent the replacement of good components, be aware that the following non-EEC areas may be at fault:

• Coolant level
• Engine not up to operating temperature
• Engine over operating temperature
• A/C input (electrical problem)
• Throttle Speed Control Linkage
• Throttle Linkage

This Pinpoint Test is intended to diagnose only the following:

• Rpm in Self-Test only
• IAC Adaptive Strategy Faults
• IAC Solenoid (9F715)
• Harness circuits: IAC, and VPWR
• Powertrain Control Module (PCM) (12A650)

Description
The Idle Air Control (IAT) solenoid is used to control engine idle speed and dashpot functions. The IAC solenoid is
mounted on the throttle body (on most applications) and allows air to bypass the throttle plate. The amount of air
allowed to bypass is determined by the PCM and controlled by a duty cycle signal.

[deleted]

 

[Storm-Chaser]

DTC 542

Constant Control Relay Module


Remember

This Pinpoint Test is intended to diagnose only the following:

• Constant Control Relay Module (CCRM)
  - EEC Power Relay
  - LFC Relay
  - HFC Relay
  - WAC Relay
  - FP Relay
• Pusher Fan Control Relay
• Harness circuits: B+, KPWR, PWR GND, FP, LFP, HFP, LFC, HFC, PFC, A/C, ACCS, ACPSW, WAC
• Powertrain Control Module (PCM) (12A650)

Description

Constant Control Relay Module (CCRM)
The Constant Control Relay Module (CCRM) interfaces with the EEC-IV system to provide control for the cooling
fan, A/C clutch and the fuel pump. The CCRM may also contain the EEC power relay which provides vehicle
battery power (VPWR) to the Powertrain Control Module (PCM) and EEC-IV system. Refer to the following
schematics for specific CCRM relay control.

Pusher Fan (Thunderbird SC)
The Thunderbird SC has ….

Dual and Single Function A/C Pressure Switch (ACPSW) (also known as Refrigerant
Containment Switch)
The ACPSW is used for additional A/C system pressure control and is also known as the refrigerant containment
Switch. The normally open medium pressure contacts close at a predetermined A/C head pressure. This
Grounds the input to PCM indicating that the high speed cooling fan is required. For the 3.0L SHO and Taurus
Flex Fuel, the medium pressure ACPSW circuit is not wired to the PCM, but is wired directly to the CCRM for high
speed cooling fan control. The normally closed high pressure contacts open at a predetermined A/C head
pressure. This turns off the A/C by opening the A/C demand circuit preventing the A/C pressure from rising to a
level that would open the A/C high pressure relief valve. For additional information, refer to the
Ventilation / Climate Control group of the service manual.

[deleted]

 

[Storm-Chaser]

DTC 512

Continuous Memory
Diagnostic Trouble Code
(DTC 512)


Remember

This Pinpoint Test is intended to diagnose only the following:

• Harness circuit: KAPWR
• Powertrain Control Module (PCM) (12A650)

Description
Not Applicable.


QB1 |

CHECK KAPWR TO POWERTRAIN CONTROL
MODULE (PCM)​

Continuous Memory DTC 512 indicates the PCM
has experienced a power interrupt in its Keep
Alive Memory (KAM) circuit.

NOTE: If KAPWR is interrupted to the PCM, for
Example when installing a breakout box, or
when battery is disconnected, DTC 512 may be
stored in Continuous Memory.​

[deleted]