PCM Tune = poor gas mileage

[HARDTRAILZ]

*shrug* No harm in playing, right?

My wife's 2003 TrailBlazer LS, 4WD, I6, bought with 82k on it, was getting an average of 18 MPG, combined city/highway, when we first bought it. I haven't checked it lately. I'm hoping whatever TB I end up with will do at least the same.

I'm encouraged, tho. Of three gas mileage reporting sites I checked: The later TBs are generally reported to get marginally better mileage than the earlier ones. 2003 LS 4WD I6 average was about 17.4 MPG. The 2007 LS 4WD I6 average: 17.8.

Based on watching how my fellow drivers behave (see above): I expect to beat the averages

Jim

The harm is wasting money and time, but to each their own. I work to hard for my money. I dream of better mpg, but for what I have done to my truck. It is decent. I guess I could start rteplacing things that might be worn or could be better, but since I am in line with similar rigs...I won't waste my time or money.

If everyone agreed his mpg's were not typical or they had dropped significantly, then I completely understand, but that was not the case. He "felt" it should be better when it was right in line with many people's calculations.

 

[SEMIJim]

Short trips have nothing to do with warm ups. They are each bad all by themselves! lol

Well, yes... But what I meant was this: If you're going to drive 500 miles all in one go (okay, with a brief pit stop or two), a five-minute warmup won't matter a hill of beans to your average mileage for the trip. But if you're splitting that 500 miles up into 20 short trips, that 5-min-per trip warm-up will decrease your average gas mileage fairly noticably.

The harm is wasting money and time, but to each their own. I work to hard for my money.

I do, too, and, since I'm not a "car hobbiest" any more (used to be, back in my Woodward Ave. street racing days), I'm generally disinclined to spend any more on a vehicle than I need to for it to perform reliably. So we're on the same page.

But I would guess, just a guess, mind you , that this site has more than its share of truck tinkerers--people for whom mucking-about with their trucks is what they do for enjoyment. I understand it. I used to be one of those guys. (It was cars, not trucks, but same thing.) Heck, it can't be any worse than boats. We don't call 'em "a hole in the water into which you throw money" for nothin'!

Where I feel the OP made his mistake was in failing to make only one change at a time and taking time to evaluate its effect before making another. And try to make those changes when everything else can reasonably be expected to remain constant. In this case: Driving style, type and duration of trips, road characteristics, and weather.

He had a whole bunch of variables change. Hard to say which of them, or which combination of them, created the results he's seeing. If any.

Jim