hi all car runs ok when warm, but let it go cold and with out starting it says engine problem reduced performance,so start car wont let me go past 3000 rpm, temp gauge stops on cold for about 4 miles then goes straight to correct temp in one go ,engine problem and reduced performance imediatly go out any ideas please

 

Get an inexpensive OBDII code reader and read the fault codes. Post them up here and we wil try to help.

 

If one were to *guess* without the benefit of logging through OBD-II, the most logical guess would be the coolant temperature sensor and related circuitry.

This is a hypothesis based upon the observation that the temperature gauge shoots up to normal after 4 miles after remaining inactive beforehand. Combine this with the fact that the ECM compares the IAT (intake air temperature) with the coolant temperature as a sanity check and you can suspect that the ECM logic decides to go to restricted performance because it has no reliable coolant temperature reading.

 

hi think your right had the codes read and its the colant temp gauge got one off jag dealer hope to fit to moz let will you know