warm up and high fuel usage

[denniselbows]

evening all i wonder if you can throw some ideas my way as to what is going on .
i have notice for the last couple of months now i am down a good 50 miles on a tank of fuel. i do most of my driving doing 80mph down the motorway and latelly in the cold weather the coolant temp has been dropping down from the normal 90 to half way between the 90 and 50 now my first thoughts were the thermostat was on the way out and the high fuel usage was down to the engine not getting warm properly . so over the week end i put a new thermostat in along with fresh coolant. wilst i was in the area i checked the static timing. flywheel marks, cam timing marks, and the lines in the dizzy (3b by the way) are all perfect. now went out yesterday it now takes miles longer to warm up but doesn't really warm up at all. great i thought i knew i shouldn't of got a thermostat from gsf any way tonight i tested my old thermostat and the spair new one i bought. the new one is opening as it should and the old one is opening later than it should and not as open as the new one. so as far as i can see the one in me engine should be working correct. now this has thrown me totally have i got a fueling problem that is not warming up the engine or is it a cooling problem ?
if the engine is being over fueled will the engine run hotter than normal or colder

oh ya no fault codes stored in the ecu the olny blink code is 4444 which if i remember right is no faults pressent

any ideas welcome thanks in advance
dennis

[AUDIS2avant]

Hmm i have the same problem so listining in here

[gedu]

Well, on our finnish board we always say, use original thermostat from dealer, it works miles better than any bought from corner shop.

I didn't believe that at first, tried 2 non dealer ones, 3rd I bought from dealer, and no problems after that.

[geryS2]

got the same problem also, but i run with a stock one, i gonna change it, will post results....

[Mikes2]

I had this after replacing a thermostat.

New MFTS sorted it

[denniselbows]

was thinking about the mfts put a new one in a year or two ago doesn't that it may not be ****ed allready though what's the functions of the mfts again, does it tell the ecu engine temperature and would a knackered one show a fault code?

[AUDIS2avant]

What are MFTS ?

[denniselbows]

multy function temperature sensor just found what it does
3 functions
temperature gauge
auto check alarm
and alarm for the ecu to cut boost if alarmed
it is on the water manifold under the inlet manifold

[mcandmar]

The sensor at the back of the cyl head is what the ECU uses. From memory the resistance rises with temp, so if its faulty or disconnected the ecu thinks the engine is stone cold.

[pnanassy]

Hi,

a bit offtopic,but this is how mine works.Still not heating up to the 90C region.
Anyway,im really impressed with the overall consumption of this 11.18@202km/h capable setup.