MPG dropping

[Guvna!]

The MPG on my Phase 2 172 has steadily dropped from around 39mpg to 32mpg - I do 40 miles a day @ 60-70mph.

The car seems a bit hesitant at times when I boot it, as if it's miss firing or holding back. I've tried running it on V-Power and it rises to about 35mpg (it's got the RS Tuning 98 ron remap) but that's still poor.

Checked tyre pressures, it's got 182 cup alloys on it but that's it.

Recently been serviced, air filter is clean.

I've got an RS Tuner, any idea on what I should be looking for? It smells pretty rich on tick over.

 

[benkay]

Sounds like it could be pre-cat lambda sensor. If that starts playing up it can lead to the ecu firing in too much fuel causing hesitation and lower MPG.

 

[MartinR]

Cold weather !!! Even with the 98ron map these cars hate the cold

 

[Guvna!]

I'll stick it on the fault code reader and see what it comes up with.

How many lambda's are on the 172?

 

[MartinR]

Two...

pre and post cat

 

[Guvna!]

Plugged in my RS tuner and it only came up with one fault - brake sensor or something like that. Cleared it and it hasn't come back.

The car seems really hesitant from 2-2,500 rpm.