I had a sweet day at the local racetrack, took an intro driving course. I drove it pretty hard, keeping the revs highs and stuff, but nothing too crazy.

I used to get like 18-20 mpg, with some highway driving included. Now its like 13mpg.
There was a lot of soft rubber that was thrown by slicks on the track that I drove over and stuck to my rear tires, its just now starting to wear off.
Could that be the cause?
No visible or audible damage or changes otherwise....

 

Now that I think about it, the tire pressure is probably a bit low too. Can that really make such a difference?

 

Tire pressure can make a pretty big differnece on MPG, if its 10psi low I can see it causing that much of a dip in MPG. Checkl in to it and make sure your tires are inflated to there proper tempature. If you fill them up and you still haven the milage problem then it might be something to check into.

Im drunk so i dont know ifm my info is accurate lol but my sober side telss me this.

 

Wow. I never heard of this sort of thing befor pieter3d. How long have you had your 8? Also ask BigO. He might know. Hes like smart. He was just at the track too.

 

The engine computer could have calibrated itself for harder driving, compounding whatever losses you had from low tire pressure. I don't really know what I'm talking about, but I'm pretty sure the car will do that under the correct set of circumstances. You can try giving it a reset so it "learns" to run with a more efficient setup again.

 

^ that is what i was thinking. if you don't really push the car hard daily, and you did at this track, the ecu could have reseted... then again i never heard of this happening to anyone. yes go check your tire pressure.

 

try clearing the ecu?

 

i would re-set the ecu. When i reset mine I get about 5mpg LESS than after a few tanks of driving on the ecu.

I think the car adjusted to the differnt driving you did on the track. How much time (distance) did you do on the track, and how many 'normal' miles have you done since?

 

lol

"at least your honest"

 

newbie question> how do u clear the ECU?

 

1) With the key in the off position, press and hold the odometer reset button and turn the key to on;
Continue to hold the odo button until the odometer reads "TEST" and then release.
2) Turn the key to off and repeat step one.

This will reset the entire PCM except the KAM which contains the sensor profiles amongst other things. You can reset it with the familiar procedure:

1) Turn the key to on
2) Depress the brake pedal rapidly 20 times in a row until the oil pressure gauge sweeps to halfway and back again.

 

lol, i never even knew this. nice job on the info.

 

Sticky in the Tech Garage Section

https://www.rx8club.com/series-i-tech-garage-22/ecu-clear-reset-27548/

 

I will give that a try thanks.