Added a Halltech Stinger this weekend. I've driven the car about 100 miles so the computer should have adjusted for it by now. My fuel mileage seems to have dropped about 2 mpg?? I thought I would be getting a little better mileage since the engine can breathe easier.

 

I have seen someone else post similar results...

 

Maybe you are just driving it a little harder to test it out.


Clayton from Las Vegas

 

Thats exactly what I thought. During normal driving, even my supercharger didnt hurt my mileage, it even improved it (I clearly mentionned during normal driving )

 

My MPG didn't change after my mods...of course it took time for the computer to relearn...but I still get 27 on the highway (Automatic mind you) at 85MPH!

Haltech Stinger
Kooks LT's High flow cats\X-pipe
LS6 intake
Z06 catback

*stock tune!!!

this is with the 3:15 gear ratio...

MAybe you used a heavy foot to test! or you need to run it some more to get the computer in check...

 

No noticeable drop change in gas mileage. I have had mine installed for a few thousand miles.

 

The fuel mileage is a function of your throttle pedal. Maybe you're stepping on the throttle just a little more than you use to?

Actually, we recorded 32 mpg in 6th gear driving from Milwaukee to Chicago Heights, IL and back with the Stinger.

Here is how the Power Control Module works. During the first 15 or so miles the 20 Long Term Fuel Trims (one for each throttle position) relearn stoichiometric (a perfectly chemically correct burn or 14.68:1).

That is 14.68 parts air for every 1 part fuel, assuming gasoline or E-0.

If you get stuck using E10 (10% ethanol fuel) your mileage will go down a couple miles per gallon due to the fact that 14.68:1 is stoichiometric for 100% gasoline only. E10 requires a stoich ratio of 14:1.

Ethanol has about 60% the BTUs of gasoline, so 10% of your fuel is only producing 60% of the power the car needs to maintain level power in 6th gear.

We reprogram cars that are stuck with E10 here in WI by changing stoich to 14:1 for closed loop. The fuel mileage is still slightly less than with pure gasoline, but at least the power returns.

The other anolomly is the Cat Overtemp Protection circuit in the PCM program. It automatically adds fuel to WOT if it registers too much O2. We have seen mixtures as fat as 10.5:1 on the dyno because of this circuit kicking in.

This is another area we provide programming countermeasures to turn this circuit down a bit. It is very aggressive on the dyno, but not quite as bad on the street due to better cooling.

Jim

 

Mine was the same on my M6 coupe for the most part some days it was high some days lower. Prolly just all on the account of my foot.

 

It's the price you sometimes pay

 

I think we are all spoiled. The LS1 gets great gas mileage for the amount of performance we get out of it. 30 years ago people would have laughed in disbelief if you told them that you had a car that ran a mid to low 13 second quarter mile and had a top speed of over 170 mph AND got 30 mpg on the highway..

 

get a callaway intake, more power, no codes, better mpg!

 

I installed the Halltech on my 2000 coupe and my DIC showed I lost 2 mpg. And It wasn't due to my foot. I asked if maybe due to the more air, that the engine added more fuel to keep it out of a lean condition.

 

I've driven the car about 250 miles since my first post and I'm happy to report now that my mileage is up about .5 mpg. I drive the same loop to work everyday - 90% highway. Guess it just took the computer a little longer to adjust than I thought it would....and I might have been into the throttle pedal just a bit also.

Thanks Jim for the interesting info in your post. The BP where I get gas doesn't have any ethanol.

Great product...well engineered and good customer service.