need some input on KOEO, KOER, and memory codes

[cenok is family]

so for a long while now, my car does not want to drop to an idle when i'm coming to a stop. for instance, if i'm pulling up to a stop sign or light or whatever, as soon as i push in the clutch, the car tries to stall; i have to hold the throttle slightly to keep it from dying, and when i'm finally at a complete stop, it will idle fine (unless i don't blip the throttle and it dies).

SO, i noticed the other day my o2 harness was ripped, so i got another one and replaced it. after that, i ran the codes on her. here's what i got:

KOEO:

67 - A/C on or neutral switch open/out of range

85 - canister purge circuit failure

KOER:

94 - thermactor air system inoperative bank 2 or fuel control circuit failure

44 - thermactor air system failure

MEMORY:

29 - insufficient input from VSS

91 - no exhaust gas oxygen switching detected bank 2

ok so as far as code 67, i have no A/C so i probably need a new neutral safety switch; mine has been a bit finicky, i have to have the clutch pedal absolutely mashed to the floor to start my car

code 85, i've pulled out all the smog stuff, and i don't have my purge solenoid hooked up. will not having the purge solenoid cause any problems other than smelling gas?

the KOER codes, i know what/where the thermactor valve is, but i don't know anything about the thermactor air system. if someone could enlighten me on whether these codes will cause a problem, please let me know.

memory code 29, i'm assuming i just need to replace my VSS. do you guys think this is the main culprit in my stalling issue?

memory code 91, i need to replace my o2's anyway, but seeing as both this code and the KOER code 94 both refer to bank 2, is there something else there i might check into?

thanks for any and all help!

here's my combo, by the way:

308, Ross forged slugs, cobra intake, Thumpers w/ 1.94/1.6s, Anderson n-412 cam, 65mm tb, proflow 75mm maf, 3.5" power pipe, 24# inj, 255lph fp, 1.6 rr's, kirban afpr, u/d pullies, no a/c or smog, taurus fan w/ DC control, KC clutch, pro 5.0, 4.10s, hedman L/Ts, 2.5" H pipe, spintech prostreets, alum d/s, MAC c/c plates, MSD 6al w/ blaster coil, Taylor ThunderVolt wires, 3G alt, full-length sfc, UPR uca's/lca's, tokico struts, strange 10-way shocks, maxspeed springs, HID 5000k

 

[Mustang5L5]

Code 29 would show symptom exactly like you are seeing. No VSS on a mass air car and it has trouble maintaining idle or stalling when slowing down to a stop. On speed density cars with mass air conversion, two wires need to be added to tie the maf computer into the vss harness. On 86-88 cars, the vss is only used for cruise control and may not be present on non-cruise cars. It needs to be added and wired into the maf computer.

Code 67...you need to press the clutch down the ENTIRE time you are running codes. Not a critical code..ignore it.

85, 94 and 44 can be ignored...won't affect how car runs unless you have a vac leak

Code 91...bad o2 sensor.

 

[jrichker]

Thermactor Air System
Some review of how it works...

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

The Thermactor air pump (smog pump) supplies air to the heads or catalytic converters. This air helps break down the excess HC (hydrocarbons) and CO (carbon monoxide). The air supplied to the catalytic converters helps create the catalytic reaction that changes the HC & CO into CO2 and water vapor. Catalytic converters on 5.0 Mustangs are designed to use the extra air provided by the smog pump. Without the extra air, the catalytic converters will clog and fail.

The Thermactor air pump draws air from an inlet filter in the front of the pump. The smog pump puts air into the heads when the engine is cold and then into the catalytic converters when it is warm. The Thermactor control valves serve to direct the flow. The first valve, TAB (Thermactor Air Bypass) or AM1 valve) either dumps air to the atmosphere or passes it on to the second valve. The second valve, TAD (Thermactor Air Diverter valve or AM2 valve) directs it to the heads or the catalytic converters. Check valves located after the TAB & TAD solenoids prevent hot exhaust gases from damaging the control valves or pump in case of a backfire. The air serves to help consume any unburned hydrocarbons by supplying extra oxygen to the catalytic process. The computer tells the Thermactor Air System to open the Bypass valve at WOT (wide open throttle) minimizing engine drag. This dumps the pump's output to the atmosphere, and reduces the parasitic drag caused by the smog pump to about 2-4 HP at WOT. The Bypass valve also opens during deceleration to reduce or prevent backfires.

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.

Computer operation & control for the Thermactor Air System
Automobile computers use current sink technology. They do not source power to any relay, solenoid or actuator like the IAC, fuel pump relay, or fuel injectors. Instead the computer provides a ground path for the positive battery voltage to get back to the battery negative terminal. That flow of power from positive to negative is what provides the energy to make the IAC, fuel pump relay, or fuel injectors work. No ground provided by the computer, then the actuators and relays don't operate.

One side of the any relay/actuator/solenoid in the engine compartment will be connected to a red wire that has 12-14 volts anytime the ignition switch is in the run position. The other side will have 12-14 volts when the relay/actuator/solenoid isn't turned on. Once the computer turns on the clamp side, the voltage on the computer side of the wire will drop down to 1 volt or less.

In order to test the TAD/TAB solenoids, you need to ground the white/red wire on the TAB solenoid or the light green/black wire on the TAD solenoid.

For 94-95 cars: the colors are different. The White/Red wire (TAB control) is White/Orange (Pin 31 on the PCM). The Green/Black wire (TAD control) should be Brown (pin 34 at the PCM). Thanks to HISSIN50 for this tip.

To test the computer, you can use a test light across the TAB or TAD wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker.

Theory of operation:
Catalytic converters consist of two different types of catalysts: Reduction and Oxidation.
The Reduction catalyst is the first converter in a 5.0 Mustang, and the Oxidation converter is the second converter. The Oxidation converter uses the extra air from the smog pump to burn the excess HC. Aftermarket converters that use the smog pump often combine both types of catalysts in one housing. Since all catalytic reactions depend on heat to happen, catalytic converters do not work as efficiently with long tube headers. The extra length of the long tubes reduces the heat available to operate the O2 sensors and the catalytic converters. That will cause emissions problems, and reduce the chances of passing an actual smog test.


Now for the Chemistry...
"The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the NOx emissions. When an NO or NO2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2. For example:

2NO => N2 + O2 or 2NO2 => N2 + 2O2

The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas. For example:

2CO + O2 => 2CO2

There are two main types of structures used in catalytic converters -- honeycomb and ceramic beads. Most cars today use a honeycomb structure." Quote courtesy of How Stuff Works (HowStuffWorks "Catalysts")

What happens when there is no extra air from the smog pump...
As engines age, the quality of tune decreases and wear causes them to burn oil. We have all seem cars that go down the road puffing blue or black smoke from the tailpipe. Oil consumption and poor tune increase the amount of HC the oxidation catalyst has to deal with. The excess HC that the converters cannot oxidize due to lack of extra air becomes a crusty coating inside the honeycomb structure. This effectively reduces the size of the honeycomb passageways and builds up thicker over time and mileage. Continuous usage under such conditions will cause the converter to fail and clog. The extra air provided by the Thermactor Air System (smog pump) is essential for the oxidation process. It oxidizes the added HC from oil consumption and poor tune and keeps the HC levels within acceptable limits.

Newer catalytic converters do not use the Thermactor Air System (smog pump) because they are designed to work with an improved computer system that runs leaner and cleaner
They add an extra set of O2 sensors after the catalytic converters to monitor the oxygen and HC levels. Using this additional information, the improved computer system adjusts the air/fuel mixture for cleaner combustion and reduced emissions. If the computer cannot compensate for the added load of emissions due to wear and poor tune, the catalytic converters will eventually fail and clog. The periodic checks (smog inspections) are supposed to help owners keep track of problems and get them repaired.

 

[cenok is family]

awesome, thanks so much guys