Hi Jeff
These several engine computer "updates" you say your dealer has done
after the first of which you discovered your gas consumption had risen
noticably, do you know what was the reason for these updates? Had you
complained of driveability problems to your dealer hence he did the computer
change(s)? My truck was pinging excessively. I complained to the dealer who
scoped the engine and found all systems to be working up to par. A factory
service bulletin allowed for a warranty-paid computer update which has
greatly reduced the ping. It only does so now under really steep grades and
pulling very hard and this on 87 octane regular. I assume what my update did
was to reduce the spark advance, or so we used to call the procedure in the
lo tech days. There is a slight loss of performance but there also is a loss
of about 1mpg in gas consumption. Maybe one of your updates involved this
kind of action??
Going to synthetic motor oil could hardly be a cause. Back when I
changed over to Mobil One I began a consistent 1-2mpg increase in economy.
Paul Sahlin
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