Yours being a 1991 car I did not think it had an injector temp sensor. I thought they stopped that in 88..Air control.. ok with the engine running at normal temp, check to make sure the air valve is humming or vibrating. Be careful doing this as the enging is running and can be a safety hazzard. If it is humming then go to the next check. Engine off, disconnect the air valve plug. Check the terminals with an ohmmeter for resistance. There are two types of valve. A 3 wire connector is between outer terminals 40 ohms, center to outer terminal is 20 ohms. Check to see if the piston moves freely by moving it back and forth. If two wire then the connector is at 8 ohms. Check piston by removing the unit and applying battery voltage to terminal. If it is good it will close when applied and open when there is no voltage on the terminal.If it is defective then replace it only with the exact part number as yours....Max..:>)
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Max..1989 244 DL 5 Spd., V15 Phase II Cam Bilstein HD, Turbo Swaybars, Poly Bushings all round, Turbo Wheels, Black leather interior, Electric mirrors, LED dash and gauge lights and now NEW ECODES with the turn signals, 1992 black 244 next project