Gas milage went downhill

One other thing that might affect MPG: I noticed you said you had some electrical problems. If the engine computer (ECU) lost its memory from a bad electrical connection, it might be relearining how you drive. A few people here reported drastically lower MPG after ECU reprogramming, until the computer learned about your driving again.

Don't sweat it for now, what with all the changes Dr. Fusco mentioned. If it's still bad after 1000 miles, it may be dealer time. Oh, and dump some Chevron injector cleaner in the tank. Good reports of better MPG...

 

Our temperatures here in Sacramento are still in the 50s at night and it warms into the low 80s during the day - which is normal for October . . . so that isn't the problem.

Just this week I did the Chevron Fuel Injector Cleaner thing.
http://priuschat.com/index.php?s=&show...st&p=330154

I went from 50 – 51 MPG to an all time high of 56.2. Give it a try. It can't hurt. And it hurts even less with a box of four at Costco.

 

<div class='quotetop'>QUOTE(Bill Merchant @ Oct 10 2006, 03:05 AM) [snapback]330504[/snapback]</div>

The computer has to relearn how you drive?

 

Simply put, the car attempts to learn your driving habbits to maximize mileage and minimize emissions. Imagine two different styles: the first likes to jack-rabbit off the start, then glide down until accelerating up to speed again, while the second goes real easy from the start and maintains a constant speed.

For the first user, the car would learn to shut down the ICE as soon as the pressure was released on the gas pedal. For the second, the car probably wouldn't be that quick, as it would expect to need it again a few seconds later.

This is obviously a very simplified example. the computers do a lot of fine tuning, probably not too much that would be as obvious as i described. But you get the idea.

 

<div class='quotetop'>QUOTE(eagle33199 @ Oct 10 2006, 11:31 AM) [snapback]330608[/snapback]</div>

That is wicked cool! I always thought the only thing the computer knew how to do was manage what the accelrator was telling it at any given time. I didn't realize it could adjust to different drving patterns consistently. I love this car more each day. I am going to convince mine that I am the man! :lol: I'm not getting the 50MPG yet, so my car is obvoiusly,..... not sold on me!

 

Just keep in mind that it can't tell when different people are driving, so it can't switch back and forth. instead, if you leave town for a while and someone else drives it, their more recent history will slowly retrain the computer until it "forgets" about you... then you might end up with worse mileage when you get back, since it learned on someone else while you were away.

 

<div class='quotetop'>QUOTE(eagle33199 @ Oct 10 2006, 03:15 PM) [snapback]330779[/snapback]</div>

This sounds like an excellent argument for not lending out your car! :lol:

 

Didn't you just purchase new fancy tires? Could this be the cause of the drop to your mileage?

 

It's not so much learning how *you* drive, it's learning how to
apply long-term trim to the fuel maps. That can take a few days,
and in the case of the Prius may be affected by the way you drive
in the meantime. But it shouldn't take very long. I've depowered
my ECM many a time and gone right back out holding 70+ mpg average
over arbitrary lengths of backroads in nice weather, so I don't
think the effect is all that profound.
.
I have never been shown any hard evidence for the "driver learning"
thing. Look for other changes, I'd say...
.
_H*

 

<div class='quotetop'>QUOTE(SSimon @ Oct 10 2006, 04:09 PM) [snapback]330813[/snapback]</div>

I also changed my Prius shoes for 215/45/17" and noticed a FE drop of 6.5 mpg. Now I'm back with the original rims and tires for a week or a full gas tank as a test to confirm my lower mpg's.
Besides the consecuence of FE, I love my wheels........... B)