Does anyone else notice a spike in miles per gallon during ECU learning mode? If I switch from one octane level to another, have a dealer update on the ECU, or disconnect the battery, the next tank of gas goes further. This peak of MPG is followed by a steady decrease back to normal (poor) fuel consumption.

Or is it just me

Doug DeBug

 

I have not noticed this behavior with my car and I check my mileage after every fill-up. I usually get around 20mpg in 75h/25c driving using Shell 87 octane.

What's your mpg observations (some numbers please) during the ECU mode and do you notice any difference in power during and after the learning mode?

 

How does your 8 run on 87 octane?
Everything I've read says to use 91 or 92 octane...
Perhaps I'll try 87 with my next fill-up...

 

this is the first i've heard of anyoen using 87 octane...thought we were supposed to use premium fuel?

 

OK you guys have to understand that when ur 8 is warming up.... it eats gas.. untill its warmed up ur mpg will suck.. so if you pull into a gas station and ur Eng is up to temp..
When you fill up and then drive for a good distance your MPG will be much higher then if you had a Full tank and then went the same distance with a cold ENG to start with.....


Im just sick of this whole MPG threads...

Sry if im sounding like a A hole.

=) Happy new years.

 

ah but the ecu does adapte to your driving technic doesn't it..so if you unpluged and reset your ecu befor you went on a highway trip (after you drove primarily in the city) it would give you better mpg...not sure how much as i am probable making things up again:p

 

Quoting from page 4-2 of the owner's manual:
"Your Mazda will perform best with fuel listed in the table."

Table contains: "Premium unleaded fuel" Octane: "91 [ (R+M)/2 method] or above (96 RON or above)"

Then under the table:
"You may use a regular unleaded fuel with Octane Rating from 87 to 90 (91 to 95 RON) but
this will slightly reduce performance."

I decided that I could live with "slightly reduced performance" in exchange for fuel $$$ savings, but I use Shell primarily. My car runs just fine with my driving style ...... I don't live the the red line zone.

IIRC one person recently wrote that they live/drive in the red line zone with 87 octane and have not had any issues.

There are a number of people of the forum that run 87 octane with no problems and some that tried it and swore they'd never use it again.

 

You must like getting sick then ........ else why would your read and post in mpg threads .

 

Hey!
Thanks for the info!

 

The only octane level I have ever used is 87...The car runs well.

 

I want to explore this thread further guys....

Im guessing that ECU resets put the default Fuel Air mixture at some setting that others claim gets better MPG.
Does anyone have a Canzoomer than can verify?
I have noticed a HUGE MPG decrease based on the weather we are having in AL right now. (50-60 deg F daytime, 24-36 def F night)
Also the power seems to be crappy too.
This has been the worst MPG I have had yet!
I usually get about 240 miles in a tank before idiot light, now I get about 180-190.
It has started to warm up a little and it seems to be improving.
Is this behavior due to hovering and crossing freezing point?

My daily driving profile is like this:

Start car in garage that is about 10-15 degrees warmer (34-46 deg F) than ambient into air at temps mentioned above.
Drive 30-50 mph for roughly 5 minutes to highway. (No revving.)
Hit highway and travel 70-80 MPH for 25 miles to work.

During day...several short trips (<5 miles) between work locations where car barely heats up.

Heading home..its dark and cold by now...start car in ~40 deg F and head back home reverse of above.

Any similar stories?

 

I always use 93 octane.

 

I have the AT tranny, so I don't really know what performance is. I have used 87 octane since getting the car and the MPG's are about 10% higher than the 2 tanks I put in of 92 octane. Mileage is 22-23 highway and 14-16 city.