code 81

Nicoleb3x3 · Aug 10, 2006

I have a flashing code 81 and sometimes it stays on a bit longer than others, 10 mins or 2 mins...

code 81 info:
81 (o): TAD or AM-2 (Thermactor Air Diverter)/ Secondary Air Injection
Bypass (AIRB), or IAC (Inlet Air Control, SHO only) solenoid circuit
failure, or SCVNT (Speed Control Vent) circuit failure (IVSC test).

I recently replaced by IAC...is it leaking from the gasket maybe??
do I have some vacume leak somewhere?

what should I chase first?

Marlboro_Man · Aug 10, 2006

That has to do with the SMOG system, not the IAC.

Do you still have a smog pump on the car?

Nicoleb3x3 · Aug 10, 2006

smog was removed...but the code could maybe point to a vacume leak?

it usually happens first thing in the mornings...for the half hour to work my car has a slight vibration not to bad, but I can tell it's a bit "rough"

my lunch time no check engine light, and the car runs a bit better...

Marlboro_Man · Aug 10, 2006

I don't think the code would indicate a vacuum leak, but i'm no expert by any means.

Maybe Jrichker can shed some light on that one. He's one SMART man!

If you don't have a vacuum gauge handy you should be able to pick one up at your local auto parts house for under $20 or so. Check and see how much vacuum you have and let us know.

My smog and egr equipment has all been deleted by the previous owner and therefore i throw this code always, with no funny driveability issues (that i know of).

Nicoleb3x3 · Aug 10, 2006

k, thx
maybe my slight issue is totally unrelated to the code

Lash · Aug 10, 2006

That the only code you had?

Marlboro_Man · Aug 10, 2006

Try running the KOER test yet?

If not try it out.

http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

90_Red_LX · Aug 10, 2006

I get that code too. It's because the smog tube broke off where the rubber meets the metal and I don't want to fix that pos.

jrichker · Aug 10, 2006

The smog pump has two vacuum operated valves. The first valve either dumps the pump output to the open air or directs it to the next valve. The smog pump dumps its output at full throttle to save horsepower. The second valve directs the air to either the passages in the heads or to the tube that runs to the cat converters. Both the tube for the head and the tube going to the cat converters have one way check valves to prevent the hot exhaust gas from backing up into the tube and the control valves. The extra air aids the catalytic converters in converting the excess HC & CO into water & CO2.

See http://www.veryuseful.com/mustang/tech/engine/images/88Stang5.0Vacuum.gif for smog pump vacuum line help

Here are some of the codes generated by faulty parts in the smog pump system and their fixes...

Codes 94 & 44 - Check vacuum lines for leaks, & cracks. 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 wheelwell 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.

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

Code 81 – Secondary Air Injection Diverter Solenoid failure AM2. The secondary air diverter solenoid valve isn’t working on the Thermactor Air System (smog pump). Look for broken or missing vacuum lines on the solenoid valve to the diverter valve. The solenoid valve is located on the back side of the passenger side wheel well. Check the solenoid valve for +12 volts at the Red wire and look for the Lt Green/Black wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the LT Green/Black wire for the solenoid valve.

Code 82 – Secondary Air Injection Diverter Solenoid failure AM1. The dump valve air diverter solenoid valve isn’t working on the Thermactor Air System (smog pump). Look for broken or missing vacuum lines on the solenoid valve to the diverter valve Check the solenoid valve for +12 volts at the Red wire and look for the Red/White wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the Red/White wire for the solenoid valve.

Putting the computer into self test mode will cause all the actuators to toggle. This can be done either with a jumper wire or code scanner.

Nicoleb3x3 · Aug 11, 2006

ok...well I deleted my smog entirely...maybe I have my vacume lines wrong, or arranged in a way that's not teh best?

I have no canister purge, no air pump, no thermactor thing on the back of the heads anymore, and no cats (I have an off road xpipe). nothing of the smog system remains.

I had a vacume line that came out of the passenger side fender vacume ball that went into the smog purge cansiter, I took that vacume line which had no home and connected it to the vacume line that leads to what I beleive is one of thost electroic control valves that was the original destination of the vacume that would have come from the canister.

..so basically connected it so the canister was not there anymore but the vacume path is the same.

so...if I'm still using thse electroic controlled vacume valves...would it give me vacume trouble?

I think I noticed today my engine seems to be rough when it's cold and runs better when it's hot...but It's so hard to tell when it's a slight vibration..like a bit rough sometimes. Then...other times it seems to smooth out

Nicoleb3x3 · Aug 11, 2006

...so there's a vacuum line that went from the charcoal canister to the fuel tank??? where? ...was I supposed to do something with that?!

I think I recall something someone told me, but I can't remember!

--edit--
ok...I think I thought that was a vacuum line and hooked that up to the vacuum system and that is likely my prob...I'll try disconnecting it and see what happens

jrichker · Aug 11, 2006

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

Diagram courtesy of Tmoss & Stang&2birds

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

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

http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Nicoleb3x3 · Aug 11, 2006

the dotted line going to the fuel tank...doesn't specify if it's a tube that could be confused with a vacuum line! Does anyone know if that dotted line goes through the passenger fendwell?

I'm very greatful for the help so far, but I need a "real life" description of this canister connection to the fuel tank...and the location. is it a black plastic tube the size of a vacuum line going into the fenderwell on the passenger side?

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