2002 Volvo C70 Excessive Gas Mileage Decrease

PFETNER

MEMBER
2002 VOLVO C70
4 CYL
2WD
AUTOMATIC
29,000 MILES

After a "full tune-up" w/all new sparks, oil, fluids, etc. I drove from the mechanic & instantly went from 20mpg to 12.5mpg. There is also a strong smell of gas when I now start up which lasts for about 1-2 minutes. I went back to the mechanic & he informs me that it's an electrical issue. I ask that you arm me with other possibilities before he starts messing with yet another area (if I go back to him at all). Thanks

1 Reply

JIS001

MECHANIC
3,411 POSTS

Has the check engine light come on? If it has then the code can give you an idea as to where to start diagnosing. You can have a dead oxygen sensor where it is telling the ECM there is a lean running condition causing it to make it run richer. You can have a faulty engine coolant temperature sensor foolling the ECM it is still cold making the ECM to run richer to try to get it to warm up faster but usually if that happens you can also have a very high idle. You can have leaking injectors also? Also how is the driveability? After the repair did it run worse? You need to have it diagnose to see what the problem is. If you do not trust what the shop says take it in to another shop for a second opinion.