[GhostWolfGT]

I couldnt find any info on this but here is my issue.

In my '04 Golf I have been running 50 mile tests at 65mph 5 days a week for the past few weeks. Temps have been between 30°f and 60°f. No matter what changes I make to driving habit, tire pressure, and even speed, my FE is horrible if intake temp drops below 48°f.

Since i do 50 mile increments i go by fuel used. If temps are in the 50s then fuel used is consistently in the 1.35 to 1.42g range (depending on what im testing) at 65mph. 70mph is 1.45g and 75mph is 1.60g. On 4 different tests under 48°f my fuel used was above 1.45 at 65mph. Tire pressure was at 40psi and hadnt changed.

Its like this all the way down to 31°f. No change in economy between 31° and 48°. The changes start above 48° like an instant eco button. Avg mpg on these tests range from 36 to 46. But below 48° it stays around 30 to 32.

I guess im asking if the ecu is going into some default crap eco mode below 48° for whatever reason?

I drive 300 miles a day. The test route is the same starting point every time, after 10pm, no traffic, i set cruise. I fill up at the same spot each day So 1/2 tank every time i start. No load in the car. Weighs the same each time.

Im about to do a WAI anyway so i guess this is pointless but I still want to make sure im not crazy.

OK. Ive typed way too much. Going to bed. Thanks.