so i have an s4 TII without any emmissions ac etc , and an s5 turbo setup.

my probs are many but right now im trying to deal with my rich mixture and reading up on it ive noticed allot of probs with thermos sensors. my ? is would a bad thermo sensor cause my temp gauge to not move, that orange water temp light to glow and me to get like 6-8 mpgs ?

 

I may be mistaken, but I believe the water thermo sensor would only cause the fuel mixture to be richer during start up and warm up periods, not during actual driving at operating temps. The water THERMO sensor is located on the rear of the water pump housing, under the alternator, it tells the ECU how hot the coolant is.

The water temp gauge is not moving and the light is glowing because the water TEMP senor is most likely kaput. The water TEMP sensor is located on the driver side of the rear iron. Be sure you know exactly which year model your rear iron came from when looking for a replacement as there are different variants from year to year and they don't match up. Get this replaced immediately since heat is the most dreaded enemy of rotary engines, and you dont know how hot it is running.

 

The water thermosensor does not feed your gauge, thats by the oil filter. All the thermosensor does is provide the ECU with fuel trim information based on coolant temp.

 

I thought the factory failsafe for no or bad water thermo sensor was an 80 degree F. Constant. That would definalty throw off your fuel trim.