Evening all,
Today a friend and I changed the thermostat on the golf.(a 2005 GTI) and was a bit more involved than I had thought. To change it we took the alternator out, so had the battery disconnected. The battery was undone for about 3 hours in total. We put in all back together and all went well. When finished, the car coolant was topped up to the correct levels, brought up to temp etc etc.
This is the strange bit. Driving home the car was getting hardly any boost at all, it was completely flat. Then slowly it got a bit better and by the time I got home was still lacking in power but far better than when I left. The mpg took a long time to sort itself out and wasn't returning quite as good as normal by the end of the drive. The car has a revo remap, and at first it felt way less than the standard map, and then after a while it felt more than the standard map but less than the remap if you know what I mean.
While changing the thermostat we had the front diagonal intercooler pipe off at the top and bottom to ease access. When we got home we thoroughly checked everything we could see around the engine incase we had knocked off a vacuum pipe or something off without noticing. We checked the intercooler pipe too for tightness and signs of blowing too but we didn't find anything out of the ordinary.
The problem isn't with the thermostat, but something has happened to the cars power and maybe mpg also.
Would having the battery disconnected for 3 hours plus have reset the ecu? Is it now relearning and will get back to what it was?
I'm a bit confussed and maybe a little worried. Any knowledge or advice would be grately appreciated.
I'll find out if the new thermostat has made a difference in the morning when I go for a drive.