Chevy & GMC Vans

Cobra wrote:any suggestions to improve this?

Think of your brake pedal as the enemy, every press is fuel wasted. I do a lot of neutral coasting, couple places around town I can coast the van for over a mile without tying up traffic. I love seeing 99 MPG light up the Info Center. I coast to lights and stop signs, almost never touch the brakes until the van is under 15 mph already. At long lights that I know the light sequence, I shut my engine off. Know your route before hand, if in town can you take a route where the uphills aren't as steep without adding much distance? Park your van where you can pull forward when you leave, backing into spots where appropriate. Takes less gas to back into a spot with a warm engine/trans, than to back out of a space cold.

On GasSavers.org alot of people have their tires inflated to 40 PSI, haven't tried it yet myself, but considering it. Might be better for you because lower in town speeds won't heat he tires as much.

If your van doesn't have an Info Center or Tachometer, get a ScanGaugeII. Keep the current MPGs displayed to make you more conscious of how your driving effects MPG and the RPMs try to keep under 2K while getting under way.

With a weak fuel pump, random cylinder misfire, and a lot of city driving helping my sister move, I was still able to have Grumpy average almost 16 MPG.

i have a tendency to speed while the suns up...... so i'll just give up on the mpg for now...


in the middle of the night i did a run to sudbury from my home on half a tank of gas that was like.... 340km

my stock 2003 AWD Astro gets about 15 mpg city with 225/70-16 BFG TA KO's. these are strong but heavy tires.
they weigh 3 to 5 pounds more per tire than a highway type P rated 215/75-16. Skinny light low friction tread pattern tires due save gas. look at the skinnies on a Prius.

I was thinking of installing a relay and dash mounted switch open circuit the ATC fuse in the under hood fuse box to shut off the AWD. I wonder is this will help mileage. Also, is there any problem or damage to the AWD if I switched off AWD for summer street use?

thanks,

Astrophysics.

Astrophysics wrote:my stock 2003 AWD Astro gets about 15 mpg city with 225/70-16 BFG TA KO's. these are strong but heavy tires.
they weigh 3 to 5 pounds more per tire than a highway type P rated 215/75-16. Skinny light low friction tread pattern tires due save gas. look at the skinnies on a Prius.

I was thinking of installing a relay and dash mounted switch open circuit the ATC fuse in the under hood fuse box to shut off the AWD. I wonder is this will help mileage. Also, is there any problem or damage to the AWD if I switched off AWD for summer street use?

thanks,

Astrophysics.

You might be best to pm LiftedAWDastro for advise on that subject.I don't know that answer to that.

ihatemybike wrote:

Cobra wrote:any suggestions to improve this?

Takes less gas to back into a spot with a warm engine/trans, than to back out of a space cold.

Don't take this the wrong way but,you've officially crossed the line into becoming an obssesive compulsive gas saver,lmao. Time to hang up the keys and hop back on that bike of yours

'99 AWD (stock, 3.42s), 14-16, before a major tune-up where I found damaged plug wires, no data yet after the work...my 1993 LT (W motor, stock, 3.42s) used to get about 17-18, my 1991 4x4 (4.3, 3.73s) is hanging at 15, it has dropped a bit for unknown reasons, prolly a heavy right foot, lol, my 1989 (TPI 305, cam, long tube headers, 3.73s) has seen from 15 to 20, depending on speed, driver input. My 650 Yamaha is averaging 150 miles to 3 gallons of gas, which is 50 mpg. I've already put over 600 miles on it since March, no more than 15 miles at a time.
The best mileage I've seen from an Astro was the 1994 windowless shorty cargo that is sitting with a bad trans in my yard right now. When it was running, I managed 22 mpg on the interstate. It was stock, skinny tires, 3.23 gears, only hauling a small tool box and some supplies.

Well this is a guesstimate at this point but it sure looks like i'm getting 24 mpg with my new engine & trans combo. What compression ratio are you running to require higher octanes? I am running a 305 with vortec heads and my comp ratio is 9:7 to 1 and never had any bad results with 87 octane. I also have 3:23 gears and at 70 mph my RPM's at at aprrox 2100
( just got the tach hooked up) Next I am rebuilding the whole rear axle with a G80 posi , adding steel leafs, a sway bar, new shocks and the 11 inch drum conversion all in one weekend. That ought to be a fun weekend.
should take place possibly next month depending on my DJ schedule.

DJ, I'm impressed with the fact that your 9.7:1 CR engine can run on 87 octane--I sure wish my 305 could and I believe its CR is only 9.3:1. It doesn't even take well to 89 octane, so 92 is what it wants. I might find that acceptable if the engine had any 'nads, but the 305 in my 89 Astro is a real pooch.

GEJ wrote:The same 1994 LT Astro and when I went to Bristle Tn to dolly tow Ole Yellar home I had to tow the dolly empty down there and then back home to Roch.Got 15.9 mpg.Then again to Cinni with a empty dolly and back home with the LT towing.Got 19.9 mpg.Huh??.This is one I will never firgure out. #-o #-o Only difference was a hole in a muffer being bigger.

I just read this thread and Gary didnt you do an EGR repair in between the trips so wouldnt that help some?

Astros are, as a rule, very hard to get the tank all the way full on every tank with the rocket propelled station fuel pumps and small dia unleaded pump ends. Whomever designed the late Astros filler system should be shot. I figure the mileage on every tank but take it "with a grain of salt" untill I have several tanks to average together. GM even advertized the 27 gal tank capacity as everything between 25 and 27.

astrozam wrote:

ihatemybike wrote:Takes less gas to back into a spot with a warm engine/trans, than to back out of a space cold.

Don't take this the wrong way but,you've officially crossed the line into becoming an obssesive compulsive gas saver,lmao. Time to hang up the keys and hop back on that bike of yours

Not completely, there's other things I could be doing too. I still don't drive at or below the speed limit, but I'm slower than I used to be. I hope to ride my bike to work a couple days next week. I figure I have three trips to work and back left in my current tank. I have to drive on Monday and Tuesday, Wednesday it's supposed to rain. Just trying to get a tank to last me two weeks while still getting to work and doing everything I need to. It was nice not entering any gas money for the van into the family budget spreadsheet this past week.

HPbyStan wrote:Astros are, as a rule, very hard to get the tank all the way full on every tank with the rocket propelled station fuel pumps and small dia unleaded pump ends.

When I fill up I use the fast setting till it clicks off, then use the slow setting till click off, then go up to the next even dime. Seems pretty consistent.

With my recent tune up I get 16MPG Hwy mileage. I am considering putting my 225-75-15 BFG Long Trails back on to save gas. Before the lift and the 235-75-15 BFG AT's I was up to 20 MPG Hwy...But the cost of mounting and balancing 4 tires seems hardly worth it, but 4MPG would come out to 100 more miles to a tank of gas, so maybe I will buy these rims, http://store.summitracing.com/partdetai ... SW-70-5750 , mount my Long Trails on them and put the AT's back on in the winter...

The same 1994 LT Astro and when I went to Bristle Tn to dolly tow Ole Yellar home I had to tow the dolly empty down there and then back home to Roch.Got 15.9 mpg.Then again to Cinni with a empty dolly and back home with the LT towing.Got 19.9 mpg.Huh??.This is one I will never firgure out. Only difference was a hole in a muffer being bigger.

difference is elevation...to get to bristol involves hills (appalacians) cinci doesn't involve as many...i used to drive from eastern kentucky to central south carolina every other weekend, with asheville, nc a rough middle point, i would fill up the geo prizm there and would end in sc with about 1/2 a tank, and coming back ending in ky would be 1/4 or under...it's downhill elevation from ky to sc...

this was best shown in my s-10 blazer the last time i went down there, i didn't even fill up in asheville, rather going to a gas station after spartanburg, sc when i got to 1/4 tank, on the trip back i was right at 1/4 tank at asheville, and this was using the cruise control and no a/c... i never figured the mpg's i was getting, because i'm lazy and only do math if i have to...

Hey Stan,
What are the mileage figures on the LSI??

It WAS doing 17ish in town and 20-21 on the highway before the 3.73 rear gear swap but it only gets run in warm weather so it's not totally fair to compare to the AWD V6 that mostly is used in cool / cold weather. I just bought one of those plugin thingies to reset my own computer to correct gear ratio etc. Haven't got to it yet tho.