Ran Codes on my 91 GT and got only 10, 11, and 85?


Oct 21, 2009
I ran codes today on my mustang gt with a digital code reader (obd1) and did both KOEO and KOER and only came up with codes in KOEO...Codes 10 (Don't know), 11 (System Ok), and 85 (Either 3/4, 4/3 Shift Solenoid or Canister Purge Solenoid Failure). I'm trying to figure these out sense my car idle surges when in park after it's been warmed up. It will only surge maybe 100-200 rpms sometimes 300 rpms from 600ish - 950 ish.

No Check Engine Light either....
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I ran KOEO codes again and came up with 85(O) 10 (Code Spacer) and 33 (C). I looked up 33 and it's EGR Valve Not Opening Properly. I don't reckon I have it even wired up as the vacuum line going from the EGR Valve is not hooked up or capped off.
I've tried with the engine running and get nothing. I've also noticed that the vapor line that runs along the pass. fender isn't connected on the front end to anything.

Charcoal Canister Vapor Line

Where EGR Valve Vac Line Runs To.

Manifold Vac Line with Screw in it.

Where Manifold Vac Line Runs from (Behind Intake Manifold)