5.0 running rich pulled codes 21, 31, 44, 22, 66

will1992 · Aug 9, 2010

my 92 mustang has been running really rich and today and it finally happened the cel came on so i pulled the codes. here is what i got

koer:
code 21- ect out of range

code 31- pfe, evp or evr circuit below minimum voltage

code 44- thermactor air system inoperative-right side

koeo continuous memory:
code 22- bp sensor out of self-test range

code 66- maf circuit below minimum voltage

i have checked the salt and pepper shakers, and i also checked the ecu but i didnt find anything wrong. the car has a "new" j/y maf, ne egr sensor off of a explorer 5.0, new map/bap snsor and new ect. it is running a bit rich, i almost passed out from the fumes. i have a exhaust leak on the pass side so that prob would explain the thermactor code. i have performed a cylinder balance test and got a 9. the intake smells like raw gas or exhaust in the throttle body. where should i start checking

Mustang5L5 · Aug 9, 2010

Kinda funny that all the new sensors you installed are the ones displaying codes.

The exhaust leak could cause the code 44...and this won't affect the way the car runs.

All the other codes are major....ESP 21, 22 and 66.

I would suggest testing or a new ect, maf and bap...but you said you just changed these? Did you erase the codes after and retest?

will1992 · Aug 9, 2010

yeah after i replaced the maf, ect, and bap/map i left the negative battery cable unplugged for a day and started her up and got no codes, now after running a few times the Cel came on and i got the codes. how do i test those sensors?

jrichker · Aug 10, 2010

Code 21 or 116 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor.
Note that that if the outside air temp is below 50 degrees F that the test for the
ECT can be in error. This code may go away as the engine warms up, so don't dump the codes
on a cold engine

The ECT sensor has absolutely nothing to do with the temperature gauge. They are
different animals. The ECT sensor is normally located it the RH front of the engine in
the water feed tubes for the heater.

The ACT & ECT have the same thermistor, so the table values are the same

ACT & ECT test data:

Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate
readings.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is
a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower
intake manifold, the voltage readings will be lower because of the heat transfer.

Voltages may be measured across the ECT/ACT by probing the connector from
the rear. A pair of safety pins may be helpful in doing this. Use care in doing it
so that you don't damage the wiring or connector.

Here's the table :

50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.

50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms

Diagram courtesy of Tmoss & Stang&2birds

CODE: 31 (KOEO) - EVP circuit below minimum voltage. Sensor removed or disconnected, Vref (5 volt reference voltage supplied by the computer) missing or broken wire or bad connection in circuit. Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or MAP sensor located on the firewall near the center of the car. Use the black/white wire for the ground for the DVM.
With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Pull the passenger side kick panel and measure the voltage at the computer. You will need to remove the plastic cover over the wires and probe them from the backside. A safety pin may prove very useful for this task. Use pin 27, EVR input (brown/lt green wire) and pin 46, signal ground (black/white wire) to measure the voltage. The orange/white wire is Vref and should always be 5 volts -/+ .25 volt. Be sure to measure Vref at the EGR sensor to rule out any broken wires or bad connections.
Measuring the voltage at the computer helps you spot broken wiring and intermittent connections.

Codes 44 & 94 - AIR system inoperative - Air Injection. Check vacuum lines for leaks, & cracks.

Revised 28-Oct-2009 to correct code definitions and operation.

Code 44 RH side air not functioning.
Code 94 LH side air not functioning.

The computer uses the change in the O2 sensor readings to detect operation of the Thermactor control valves. When the dump valve opens, it reduces the O2 readings in the exhaust system. Then it closes the dump valve and the O2 readings increase. By toggling the dump valve (TAB), the computer tests for the 44/94 codes.

Failure mode is usually due to a clogged air crossover tube, where one or both sides of the tube clog with carbon. The air crossover tube mounts on the back of the cylinder heads and supplies air to each of the Thermactor air passages cast into the cylinder heads. When the heads do not get the proper air delivery, they set codes 44 & 94, depending on which passage is clogged. It is possible to get both 44 & 94, which would suggest that the air pump or control valves are not working correctly, or the crossover tube is full of carbon or missing.

Testing the system:
Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect
the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump
the pump's output to the atmosphere or pass it to the next valve.

The next vacuum controlled valve directs the air to either the cylinder heads when the engine is cold or
to the catalytic converter when the engine is warm. Disconnect the big hoses from the back side of the
vacuum controlled valve and start the engine. Apply vacuum to the valve and see if the airflow changes
from one hose to the next.

The two electrical controlled vacuum valves mounted on the rear of the passenger side wheel well turn the
vacuum on & off under computer control. Check to see that both valves have +12 volts on the red wire.
Then ground the white/red wire and the first solenoid should open and pass vacuum. Do the same thing to
the light green/black wire on the second solenoid and it should open and pass vacuum.

Remember that the computer does not source power for any actuator or relay, but provides the ground
necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side
will go to ground or below 1 volt as the computer switches on that circuit.

The computer provides the ground to complete the circuit to power the solenoid valve that turns the
vacuum on or off. The computer is located under the passenger side kick panel. Remove the kick panel &
the cover over the computer wiring connector pins. Check Pin 38 Solenoid valve #1 that provides vacuum
to the first Thermactor control valve for a switch from 12-14 volts to 1 volt or less. Do the same with pin
32 solenoid valve #2 that provides vacuum to the second Thermactor control valve. Starting the engine
with the computer jumpered to self test mode will cause all the actuators to toggle on and off. If after
doing this and you see no switching of the voltage on and off, you can start testing the wiring for shorts to
ground and broken wiring. An Ohm check to ground with the computer connector disconnected & the
solenoid valves disconnected should show open circuit between the pin 32 and ground and again on pin 38
and ground. In like manner, there should be less than 1 ohm between pin 32 and solenoid valve #2 and pin
38 & Solenoid valve #1.

If after checking the resistance of the wiring & you are sure that there are no wiring faults, start looking at the
solenoid valves. If you disconnect them, you can jumper power & ground to them to verify operation. Power &
ground supplied should turn on the vacuum flow, remove either one and the vacuum should stop flowing.

Typical resistance of the solenoid valves is in the range of 20-70 Ohms.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

See http://forums.stangnet.com/attachment.php?attachmentid=50636&d=1180923382 for a very nice drawing of the Thermactor Air System (smog pump) plumbing

If you have a catalytic converter H pipe, you need to fix these codes. If you don't, then don't worry about them

Code 22 or 126 MAP (vacuum) or BARO signal out of range. The MAP or BARO sensor is pretty much the same sensor for both Mass Air & Speed Density cars. The main difference is where it is connected. Mass Air cars vent it to the atmosphere, while Speed Density cars connect it to the intake manifold vacuum. Its purpose is to help set a baseline for the air/fuel mixture by sensing changes in barometric pressure. The MAP or BAP sensor puts out a 5 volt square wave that changes frequency with variations in atmospheric pressure. The base is 154 HZ at 29.92" of mercury - dry sunny day at sea level, about 68-72 degrees. You need an oscilloscope or frequency meter to measure it. There a very few DVM with a price tag under $40 that will measure frequency, but there are some out there.

The MAP/BARO sensor is mounted on the firewall behind the upper manifold on 86-93 Mustangs.

Baro or MAP test using frequency meter - run the test key on engine off. The noise from the ignition system will likely upset the frequency meter. I used a 10 x oscilloscope probe connected from the frequency meter to the MAP/BAP to reduce the jitter in the meter's readout.

If it is defective, your air/fuel ratio will be off and the car’s performance & emissions will suffer

Some basic checks you can make to be sure that the sensor is getting power & ground:
Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.
Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery cable. It should be less than 1.5 ohm.

The following power on check requires you to turn the ignition switch to the Run position.
Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or EGR sensors. Use the black/white wire for the ground for the DVM.

Code 66 MAF below minimum test voltage.
Insufficient or no voltage from MAF. Dirty MAF element, bad MAF, bad MAF wiring, missing power to MAF. Check for missing +12 volts on this circuit. Check the two links for a wiring diagram to help you find the red wire for computer power relay switched +12 volts. Check for 12 volts between the red and black wires on the MAF heater (usually pins A & B). while the connector is plugged into the MAF. This may require the use of a couple of safety pins to probe the MAF connector from the back side of it.

There are three parts in a MAF: the heater, the sensor element and the amplifier. The heater heats the MAF sensor element causing the resistance to increase. The amplifier buffers the MAF output signal and has a resistor that is laser trimmed to provide an output range compatible with the computer's load tables.

If you have a K&N flat panel filter or other filter that requires oiling, excess oil may coat the MAF sensor element and cause problems.

The MAF element is secured by 2 screws & has 1 wiring connector. To clean the element, remove it from the MAF housing and spray it down with electronic parts cleaner or non-inflammable brake parts cleaner (same stuff in a bigger can and cheaper too).

Changes in RPM causes the airflow to increase or decease, changing the voltage output.. The increase of air across the MAF sensor element causes it to cool, allowing more voltage to pass and telling the computer to increase the fuel flow. A decrease in airflow causes the MAF sensor element to get warmer, decreasing the voltage and reducing the fuel flow. Measure the MAF output at pins C & D on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9 on the computer. Be sure to measure the sensor output by measuring across the pins and not between the pins and ground.

At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt

Check the resistance of the MAF signal wiring. Pin D on the MAF and pin 50 on the computer (dark blue/orange wire) should be less than 2 ohms. Pin C on the MAF and pin 9 on the computer (tan/light blue wire) should be less than 2 ohms.

There should be a minimum of 10K ohms between either pin C or D on the MAF wiring connector and ground. Make your measurement with the MAF disconnected from the wiring harness.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel pump, alternator, ignition & A/C wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Computer,. actuator & sensor wiring
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Fuse panel layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

Vacuum routing
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

will1992 · Aug 10, 2010

man thats alot of things to do but it has to be done ill check as much stuff tomorrows as possible, thanks guys

will1992 · Aug 10, 2010

here are my results, i couldnt test the bap bcause i dont have a frequency meter

code 31- evp- pin 27, 46 is at .55v im going to try this test tomorrow again on the sensor

code 21- ect- pin 7, 46 is at 2.62 v @86 degrees

sensor has 27.27 ohms resistance (engine cold)

code 66- maf- its getting 11.59v
pin 50- 3.8 ohm resistance
pin 9- 1.1 ohms resistance
pins c and d could not get reading on the sensor

does leaving the neg bat cable unplugged for a few days clear codes off the ecu?

code 22- bap- orng-blk/wht wires @ 4.98v.
blk/wht wire resistance test;
baro- egr= .6 ohms
baro- tps= .6 ohms
baro- bat cable= .9 ohms

edit- also there were two ground wires hooked in one spot right below the computer, and one of the wires was bare, with no insulation or anything, is that right or should that wire have something on it.

will1992 · Aug 11, 2010

i checked the maf sensor and i couldnt get a ohm reading between ground at either pins d or c does thet mean the new sensor is trash and where can i get a good one

jrichker · Aug 11, 2010

will1992 said:
i checked the maf sensor and i couldnt get a ohm reading between ground at either pins d or c does thet mean the new sensor is trash and where can i get a good one

The MAF sensor is Ok in the resistance reading. The idea is that you see an open circuit with an infinite resistance reading between the C & D pins and ground. "There should be a minimum of 10K ohms between either pin C or D on the MAF wiring connector and ground. Make your measurement with the MAF disconnected from the wiring harness."

The resistance checks for the Baro sensor look good.

The ECT reading is perfect, no problems there.

Disconnecting the battery for 5-10 minutes will clear the codes and memorized settings. Disconnecting the code reader or jumper once the codes start to dump will also clear them. It does not clear the memorized settings. The memorized settings are for things like IAB opening for idle speed control.

will1992 · Aug 11, 2010

ok thanks. but why is my car running rich. i only did the test one pin at a time do i need to do both pins c, d and ground to test the circuit correctly cause it seems like i did it wrong

will1992 · Aug 11, 2010

Will a low battery cause codes to come up. because i think i may have run the codes with a low battery after letting the car sit for a few days. so, i hooked up a jumper box to the battery and what do you know, no damn cel aaaaaaahhhhh i hate my car right now, but it still smells like fumes for a 17 ft radius. my car is a stinky pig

jrichker · Aug 11, 2010

A bad MAF will cause the engine to run rich. Go back and re-read the code 66 test path for the MAF tests.

will1992 · Aug 12, 2010

i was looking at my tab/tad solenoid vacuum lines today and i tried switching them around,and i started the car and it didnt smell like gas. i htink i had them crossed. the tab red-wht/ylw line was going to the air diverter valve and the tad red-wht/grn vac to the air bypass valve, but i'll recheck my maf tomorow anyways thank you for your help

jrichker · Aug 12, 2010

Don't guess, be sure that the vacuum lines are connected up correctly.

Diagrams courtesy of Tmoss & Stang&2birds
The diagram says 88 Mustang, but except for the vacuum line connected to the MAP/Baro sensor, it is the same for all 5.0 Mustangs from 87-93. The 89-93 Mustangs vent the MAP/Baro sensor to open air

will1992 · Aug 12, 2010

i wasnt sure if i put the sol vacuum lines on the right valves, so i found a diagram like the one above and so i looked on my car and saw that the wires werent blk/grn and red/wht and i did a search to find out what color they were so i could be 100% positive that they were hooked up right. i found the tab was red- wht/ylw and the tad was red-wht/grn. i must have mixed them up when i put everything into the fenders. so could that have been why my car smelled like gas, maybe the computer was dumping fuel into the motor because the o2 sensors werent getting any air from the pump? im not really sure if the air valves can cause this?

will1992 · Aug 12, 2010

anyways today i ended up switching the lines back because i was wrong and tested the maf.

pins a&b while running get 14.9 v
pins c&d is at idle .98 v

pin d engine off was at 3.84 ohms- bad?
pin c engine off was at .60 ohms

pin d disconnected was at 100.5 ohms
pin c disconnected was at 29.2 ohms

nothing seems to be wrong besides pin d had too much resistance but i think its ok um... i pulled the codes today and only got a 41 and 21 koer the 41 is a new code that just came up, its for the right side o2 indicates lean, that could be from my exhaust leak. the code 21 checks out fine cause i tested it and the ect was perfect

Mustang5L5 · Aug 12, 2010

Is the car nice and hot when yup run the codes? Is it a koer code?

Kinda funny how the ect checks out but the code remains. The ect is a big cause of running rich. I had a code 21 due to a bad sensor and my car wouldn't even start without flooring it sometimes.

will1992 · Aug 12, 2010

my car has a hard start prob. i pulled the codes with the engine cold while it was running. i checked the sensor when it was cold too and its perfect, im going to replace it anyway to make sure.

will1992 · Aug 12, 2010

mustangsl5,

did you fix your starting problems by buying a new ect sensor? my car usually cranks for a while and tried the iab test where you hold the throttle half way but still takes about 5-10 secs to actually fire up. how did you figure out your ect was bad?

* mustang5l5 *

will1992 · Aug 13, 2010

maybe the snsor is dirty can i clean it maybe sandpaper it where it goes into the metal coolant tube

Mustang5L5 · Aug 13, 2010

will1992 said:
mustangsl5,

did you fix your starting problems by buying a new ect sensor? my car usually cranks for a while and tried the iab test where you hold the throttle half way but still takes about 5-10 secs to actually fire up. how did you figure out your ect was bad?

* mustang5l5 *

Yes, those were my symptoms. A new ECT sensor fixed the problem.

I tested it by resistance. I unplugged the sensor, and measured the resistance across the sensor leads and found it out of spec with regards to the table jrichtker posted. It was an autozone sensor too.

I have a Ford sensor on there now...car runs great.

5.0 running rich pulled codes 21, 31, 44, 22, 66

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