Crappy Mileage, got Scan Gauge, now what?

[Herbie]

OK, since day 1 of taking ownership of my 2003 AWD, I've had worse mileage than I expected given the stats on the van. The final "straw" is the owner of a Tiger XL (hi-top camper) in a 1994 AWD chassis over on ExPo forums is getting better mileage than me, despite the massive extra weight and aerodynamic hit.

12mpg on the worst tank of gas (70-75mph) and 15mpg on the best (60mph)

I never seem to manage higher than mid-14s on a freeway blast and I average mid-low 13s on my daily driving which is a good mix of freeway, fast multilane surface streets, and a couple of hills.

I know in general the AWD will give me a penalty, but again comparing to the Tiger, this blows. This is on an all-stock (so far as I know), unloaded van ferrying one toddler and (sometimes) one other adult.

Critical items:
3.42 Gears. Stock size tires. AWD. Basically unloaded. Roof racks removed (but no effect noticed). MPG measured by dividing trip odometer reading by fuel pumped (tank filled at every stop).

Possible factors:
1) This is SoCal, so speeds on freeway are 65+, most multilane stuff is 40-50mph. Acceleration from lights, etc. is not done VERY hard (never WOT), but I can't lollygag either lest I be run over or be a hazard. Same goes for the high freeway speeds.

2) I do seem to have a slow leak in one tire, so I suppose under-inflation COULD be an issue, but I'm pretty good about keeping tabs on it and its never down more than 4-5psi.

3) Even if I try to drive at 60mph on the freeways and/or accelerate more leisurely, it doesn't seem to affect the outcome more than a few tenths.

So I ordered a ScanGauge, it arrived today. I'll have it hooked up right away. What should I be looking for? I know driving slower and accelerating less will get me some improvement, but I feel like I'm being as careful as I can be, and would like to rule out mechanical factors.

[MountainManJoe]

It'll have a lot to do with the condition of your engine.

Check:
Air filter
Timing
Vacuum leaks

Tire pressure has more of an effect than you think. Using A/C also takes away fuel economy.

I get about 15 on mine. Take other people's numbers with a grain of salt. Tiger van guy was probably going downhill with a tailwind to get 15.

[ihatemybike]

The guy with the Tiger XL is calculating his mileage the right way.

My ScanGaugeII I set to show RPMs, Present MPG, Current Trip MPG (X gauge, CMG) and I bounce between GPH, Throtle Position Sensor and Coolant Temp. My game is to raise the CMG as high as possible. Cruise control, drafting box trailer semis 2.5-3 seconds back and neutral coasting off ramps and to stops are my main tricks.

Just start experimenting, you should be able to do at least as good as Grumpy.

[thevalleyboy]

Live with the crappy mileage? You didn't happen to notice that you are driving a square box down the highway with a slightly under powered V6? alright that is arguable.... but regardless Astro/Safari - good gas mileage are you kidding me? Seriously? By a Honda Fit!

Okay I don't want to sound like a donkey - my Astro AWD sucks on gas - best I have gotten is about 17 MPG - usually about 15MPG - but around town around 12 MPG - so it sounds like you are in the ball park - That said - I bought it for $3500 and paid cash - so what else can do what an Astro does - tow 5500lbs, AWD, a van (easy access to the kids) and go anywhere? A 4 door Jeep JK sure - but no access to the kids, will go more places sure, but cost more, and bascially the same mileage, and cannot tow as much (FYI - Jeep - what the hell? I need minimum 5000lbs towing - install the 3.0l diesel!)

Cheers!

[unrreal]

when i bought my van it was getting about 13mpg and after doing some routine maintenance changed the oil and filter, air filter, and inflated tires and lets not forget removing the leaves that were stuck to the mass airflow sensor, also sprayed throttle body cleaner doing the hose with the engine on to clear the crap in there, i started seeing an improvement of about 17 mpg, also after i installed the hypertech tune in my vehicle i started getting about 20 mpg hwy and 16mpg around city driving.

[Smiliesafari]

You're right in the ball park. My Safari, 96 RWD, ( Just under 200,00 miles) gets about the same. My biggset penalty is the 900lbs of ballooning equipment that I carry. What I've noticed in my travels is that if I keep it at 60 mph it will get 3-4 mpg better than when I go faster. I've also noticed that the trip odo never registers the same mileage as the speedo odo. So, how accurate are those instruments? I guess it's the penalty we pay for having a van. It's worth it for me. There's no other vehicle that does the job as well.

[phr1$k37]

OP: What type of tires do you have? I have run over 6+ different tires and they all give me different MPG (I use to run seasonal tires, meaning Autumn/Summer, Spring and Winter I ran different tires). As you mentioned, tire inflation is very important.

With the Scangauge, set three gauges to monitor instanenous MPG, average MPG and RPM. From these three gauges you can learn where the power band of your vehicle is and when to step or not step and how much to step on the accelerator.

My driving style is all over the map. Depending on the lights and length of road I will serious get on her hard from a red to green light and coast. It is hard to explain but with the Scangauge you can see the difference. Slow and steady acceleration can consume more than a quick start that gets you to rolling speed.

*Note how your cruise control pulls like a mule and makes you look like an ass to other drivers around you? Dont forget that was programmed by GM engineers who should know the vehicle best.

Just food for thought.
That Scangauge is gonna be your best buddy ... it will tell you when you have babied the gas throttle and when you had road rage Oh yah! It will record your max speed ... be sure to clear if you are pulled over.

[Herbie]

OP: What type of tires do you have? I have run over 6+ different tires and they all give me different MPG (I use to run seasonal tires, meaning Autumn/Summer, Spring and Winter I ran different tires). As you mentioned, tire inflation is very important.

Uniroyal Tiger Paws, 215/70-16

I'm on my 3rd tank with the Scan Gauge now (after using the first two to get it calibrated), so I will see if just having it there reminding me not to be an ass will net me a mileage increase. Watching the TPS gauge shows that I rarely get over 30% throttle on my commute (up to about 50% for short-ramp freeway entry, otherwise pretty light). This tank did include hauling a half ton of concrete pavers from the Home Despot, but that's only about a 3-mile drive.

[T.Low]

I get a pretty consistant 15.5mpg on tankfulls that include short shuttle driving, freeway driving at posted or higher speeds, and some mountain road driving, up and down hills.

I've got 4:10s with 30.75" MTs.

Brian's one ton Powerstroke Sportsmobile gets the same.

I can live with 15. I'd like 17. 20 would be great but I don't think I'm willing to make the sacrifices. If it were to get down to 12 or 13 you feel like you're getting robbed and should have just gotten a full size.

[phr1$k37]

Uniroyal Tiger Paws, 215/70-16

Check the pressures, pump them up.
TLow has a lift, bigger MT tires but 4.11s. I run a bit better then him and in the city however I have smaller 29" and 3.73s.

Herbie when was the last time fluids were changed in your ride? The Diffs and transfer case? Dont forget your transfer case needs changing every ... er ... 30000kms? Anyways I had changed my diffs months ago, tranny + transfer case in May and I have gotten back some lost MPG

[Kidhauler]

There is a simple solution to this. Move to Canada and your van will get better mileage. I can garuntee that by simply moving north and doing no other mods to your truck your mileage will go up by nearly 20% when using MPG as your measure. This however will not work when using L/100km.

The reason for this is we have bigger gallons in Canada. I would check with Tiger van boy and see where he lives if he is using a Canadian gallon 4.6 liters as opposed to a U.S. gallon 3.76 liters he will be getting better mileage. Its either that or he drives like a grandpa at 50mph on the interstate waiting to get killed or he is a liar.