ignition advance

[mcrews]

02Q45 Sport.

I run a scangauge2. It is an obd2 devise that stays plugged in all the time and gives me constant/instant data.
water temp, intake air temp, mpg, mph, volts etc.
I keep it on to help with the mpgs while i'm driving.

Especially on the long trips.

THe ignition advance gauge has shown 31-34 in the past while cruising down the highway at 60-65 w/ the cruise on. while running on pretty flat highway. with 91 octane. engine temp at 193-198.

My last trip to LA from sacramento last week, the ignition advance only was at 27-29 will at 60-65. 91 octane. cruise control on. temp 193-199. rpms 18-1900.

do you have any idea why the advance would drop dowm?
My mileage was also below what I normally get.

I had a p0720 transmission code for about 3 months but got it fixed 2 weeks ago. (the trany was in 4th all the time). Did running this way 'piss off' the ecu?

I dont have any other codes and everything else seem to be running fine.

thqnks in advance

[Q451990]

Was the ambient temperature significantly warmer on your lower MPG trip?

Heath

[mcrews]

heath,

No, we've actually had pretty mild temps in CA considering whats happening else where. maybe the mid 90's
Here is a chart that I made for my last trip to texas.
fia is the intake air temp

[Q451990]

Is that 30 MPG in a Q??!!?!?!

My only guess is that the quality of fuel in one fill-up was a little different than the other and caused the ECU to change the timing a bit to avoid detonation?

Heath