"Lean cruise" is a factory equipped feature, which allows the ECM/PCM to command fuel ratios up to 18:1 under certain conditions (usually highway driving). The code exists in 01+ LS1 and "Gen III" truck PCMs but is not enabled except on exported vehicles. Australian Holden export vehicles have this feature enabled, for example. It is apparently not enabled in the US because the leaner mixtures cause NOx emissions in excess of EPA guidelines (at least on these V8s).

But, we could at least assume that GM knows what they are doing (maybe? ;-)) since they are backing those vehicles with a warranty also.

A 2005 Cobalt LS customer of ours has also shown me datalogs that seems to imply some of the US 2.2s might have lean cruise enabled as well. It's the first vehicle I've seen in the US since the 80s that has operational lean cruise.

Our HHR tunes don't change any of this (we can't really change fuel ratios during closed loop anyway, the ECM is managing it for us). We've increased timing advance in certain areas of the timing table based on our experience on the dyno, we've ditched the PE mode delay, and we've enrichened the PE ratio (factory ratios are actually too lean for best power). Automatic transmission cars also get optimized shift points.

I'm always skeptical when people tell me the performance tune increases fuel economy, but we hear it time and time again. My LS3 Corvette has seen a 2-3MPG improvement on the highway with a tune.

Now, we're working on a targeted economy tune that definitely makes some improvements and we've been hired in the past to economy-tune fleets.

We've been experimenting with some "aggressive techniques" on our 2005 Silverado 4x4, which is a really good candidate for economy improvements.

 

I am interested in an "Economy Tune" Sure I want a little better performance but the main reason I bought this car and I am doing the mods to it is to increase mileage.
My car is not a Hot Rod and will never be. I believe (some diasagree with me) that opening up the restrictive factory intake and exhaust and giving it the correct tune will help mileage. An added benifit is it sounds better and has much better performance. A car simply can not get full performance if it can not breathe. The factory timing curves are set way on the safe side to allow for bad gas, different altitudes, different driving styles.
Until I get the correct tune the intake manifold, intake filter and exhaust may not get all if any benifits because it may make it run leaner than it should. They all have to work together.

I am interested in anything in the tune that can help mileage. I really do not care to eliminate the rev limiters or change the shift points etc. Curly

 

Been reading through this and have a couple of comments/thoughts.

I've run custom tunes in the past with a 96 Vortec 5.7. The tune was installed after the intake, exhaust (including headers), upgraded ignition and electric fans were installed. Tune was done last to make sure all things were tied together for the best performance and mileage. With a heavy full size truck, a 2mpg increase shows more benefit than on an already fuel efficent vehicle. 14-16 is more benefitial than 30-32+, I think every can agree with that.

Now, with the HHR, we can just look at the listed highway mileage, 30mpg. Most seem to claim that get at least close to that, if not over. Few say they can't.

Lets look at gas at $4 a gallon (granted, much cheaper now, so benefits will be less). But at $4 a gallon, with 30 mpg, you are spending about 13.3 cents per mile. If this tune is $250, how long will you have to drive to begin to actually save on fuel? Is it really worth the money for an additional 10hp (from the chart shown)?

Now don't get me wrong, I like custom tunes, in the right application, they can make wonders. But on a stock HHR (even with bolt on's)..... I can't see the benefit.

 

True it would take a long time to recover the cost of all of my mods but I am doing it for me and I do not mind spending money to make my perform and look like I want it to.
I like this car and plan on keeping it for a long time. Might as well make it exactly like I want it.

 

Yep, economy tunes have been selling best to owners of full size trucks. We've consistently improved the economy 25%+ on these vehicles, mostly, believe it or not, by changing the shift strategy (upshift to higher gears sooner, lock TCC sooner, etc).

 

Solman98 brings out a good point.

To explain this we can use 2 different people, First is a daily driver and the second would be someone in sales. for comparison we will use the $4.00 per gallon mentioned.

For the first driver that drives an annual of 12,000 miles and getting on the bad side of the usage 22 mpg. His cost of gas for one year will be $2,181.82.
If a tune were to gain 2 mpg average his cost of gas for the year will be $2,000.00 saving $181.82.
If the gain is 4 mpg he would spend $1,846.15 with a savings of $335.66.
If the gain is 6 mpg average he would spend $1,714.29 with a savings of $233.77.

For the Sales driver that drives an annual of 20,000 miles and getting on the bad side of the usage 22 mpg. His cost of gas for one year will be $3,635.36.
If a tune were to gain 2 mpg average his cost of gas for the year will be $3,333.33 saving $303.33.
If the gain is 4 mpg he would spend $3,076.92 with a savings of $559.44.
If the gain is 6 mpg average he would spend $2,856.14 with a savings of $389.61.

Now to compare this using an average of $2.00 mpg

For the first driver that drives an annual of 12,000 miles and getting 26 mpg. His cost of gas for one year will be $923.08.
If a tune were to gain 2 mpg average his cost of gas for the year will be $857.14 saving $65.93.
If the gain is 4 mpg he would spend $800.00 with a savings of $123.08.
If the gain is 6 mpg average he would spend $750.00 with a savings of $205.13.

For the Sales driver that drives an annual of 20,000 miles and getting 26 mpg. His cost of gas for one year will be $1,548.46.
If a tune were to gain 2 mpg average his cost of gas for the year will be $1,428.57 saving $109.89.
If the gain is 4 mpg average he would spend $1,333.33 with a savings of $205.13.
If the gain is 6 mpg average he would spend $1,250.00 with a savings of $288.46.

So yes the benefit of getting your HHR tuned for mileage may take a while to recoup. Now compare the cost of a $250.00 Trifecta Tune to a Tune where you spend $400.00 or more, here is where the cost benefit is best seen.

 

The tune I had on the truck did not change the shift points at all. I did not want that option changed from the stock. The company that did mine dug through the tables and other adjustments were made. I was definately happy with the results. But I did see a 2mpg increase and about a 30hp gain at the wheels. When all was said and done, I was running about the same HP at the wheels and the factory listed at the crank.

 

What if you have a 5 speed? Is a tune worth while as you can't do anything with the shift points. What now gets tuned?

 

When you get a tune and have the Auto, there is a ECM tune and a PCM tune, With the Std transmission there is only the ECM tune. So someone with the auto trans gets a bonus.

I have a Tune in The Deer Slayer and will be putting my stock PCM trans tune back in for the winter so I stop spinning the tires on the ice.

I have also noticed the pull difference with the engine now that the temps are between 5 and 35 here now.

 

You can always do it the way I did and get more power and mileage.Torque steer is the only side affect but I like that feeling

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