Sudden poor mileage AND transmission leak

[ohnoitsyu]

My 06 has about 1700 miles on it with no modifications.



On Friday night, there were many accidents on the freeways on my drive home from work (total distance of about 23 miles). Fortunately, I wasn't involved with any of them. Unfortunately, whether I was on the freeway or side streets, I spent a lot of time idling, but still moving to the point that I couldn't really shut the engine down.



As I reached home, my overhead indicated about 11. 8 mpg, down from a normal 13. 8-14. 5 for city driving (the highest I've ever seen was 15. 3). I assumed my idle time killed me. I ran a few errands that night, and the mileage never went up (despite hitting the reset).



The fuel level was around 3/8 of a tank, and I haven't added fuel since I last filled it.



Saturday, the mileage indicated the same low numbers, so I started driving the p1$$ out of it - basically stab and steer in an effort of hopefully burning off any carbon build-up I may have had (thinking that was the problem). I drove it hard. Understandably, the mileage didn't go up. I haven't driven it this hard since I bought it. The performance was the same as normal.



Today (Sunday), with normal driving the mileage continued to be about 2 mpg low. However, I noticed about a 6" spot of automatic transmission fluid on the ground in my garage (below front of the transmission). Although I didn't start up the engine to check ATF fluid level yet, the engine oil level is correct, and I did not find any blockage in the air filter.



Any suggestions before I take time off work and take it to the dealer? Do I just need to drive it hard to burn off any carbon? What may explain the trans fluid? Thanks in advance.

 

[rbattelle]

You tried driving it hard to burn off carbon (a practice I would have advised against had you brought this up earlier... overhead mileage data is highly suspect) and all you did was possibly damage your transmission. Don't repeat the same process.



The fluid could be a sign of damage, or it could be a bit of factory overfill that splashed out during your recent hard driving. Only a transmission diagnosis will tell.



-Ryan

 

[ohnoitsyu]

I guess maybe I should describe how I drove it. I simply accelerated as quickly as I could from signal to signal (I wasn't going anywhere near a freeway) or to somewhere near the speed limit (I wasn't being that dangerous). I'm guessing that I may have done this 20-25 times throughout the day.



What kind of diagnosis would they do? The fluid smelt fine, but that doesn't mean too much.



It just seems so odd that the overhead would seemingly suddenly change parameters. I know it's not accurate, but it was some form of a baseline - now that's way off. After driving it to work tomorrow, I may have a better idea.

 

[rbattelle]

Well, like I said it *could* just be some slight overfill that "splashed" or overflowed out. Or it could be a slight leak. You haven't reported any strange transmission behavior, so I'm not ready to condemn it as physically damaged.



A transmission diagnostic would check things like line pressures at various points, and query the onboard transmission module for any anomalous readings.



It's not time to panic yet.



-Ryan

 

[Mike B.]

Funny you should mention this now. My 06 with about 5K miles on it has just sprung the same leak! The wifey pulled away earlier this evening and I noticed the spot after she left. I won't be able to check it out until tomorrow. The transmission fluid spot was not there yesterday morning.



Mike