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GMC Safari/Chevy Astro Real World MPG



  • I purchased my Astro after retiring my second Areostar, which gave me 16-18 mpg consistently. Doing the same kind or driving with the Astro, I'm getting 12-13 mpg. Dealer diagnostic found only that the "fixed" timing was 10deg retarded at idle. They didn't mention the knock sensor, but a local mechanic suggested I check it for a short. Can anyone help me locate it? Things I've done: Plugs, Cap, Rotor, Fuel Filter, Air Filter, 5 tanks of injector cleaner. Engine runs smooth, no misses, does knock on moderate acceleration. Exhaust pipe and muffler glow at night after long uphill pull. Engine really dogs sometimes on acceleration. Help
    My '94 Astrovan ( I'm saying all this as I fight back tears) get's like 4mpg period, I swear!
    Ok, really, it's probably like 12, but I don't know how to fix the problem! Someone help me!! Either the mpg's improve ASAP, or she's goin' up for sale (or "Free to good home" :mad: )
  • teal96teal96 Posts: 2
    Sounds like yur computer is in what I call "Stupid " mode,, oxy sensor or something bad, Should the computer not run due to what ever the engine defaults to this basic ultra rich mixture. I am guessing yours has the TBI deal.

    I get 20 in town with my 2 wd but the AWD we had got 14.
  • Thanks for the post, I appreciate it. I was REALLY hoping to take this van on our road trip this coming Labor Day weekend (total time is a whole hour and a half to get there) because out of both vehicles (our other is a '92 blazer) the van has air. I highly doubt I'll be able to get a round trip out of the van on a full tank though ( if map quest is right, round trip=148miles-ish). Unless my calc's are off (I was never good at math, I shamefully admit).......?
    Maybe I should just accept the idea of a friend of mine's. He said that back when our van was built (again, it's a '94) it wasn't built with gas mileage in mind. Does anyone else think that's true? :cry: curse high gas prices!!!
  • spike99spike99 Posts: 239
    We have a 2001 AWD Safari van. Based on its DIC (Display Information Center), it gets between 8-14 mpg while towing a 4,000 lbs Travel Trailer, 14-22 mpg while hauling a family of 5 with minor internal cargo and with internal light cargo with 2 adults, our van gets a consistant gets 22-25 mpg. If wondering, my van has 3.42 gearing and it did have P215/75R/15 rubber tires (which is factory size). We got new P215/70R/15 rubber tires (which are smaller / lighter tires) installed a few days ago and our van with family of 5 is now more consistantly in the 23-25 mpg range. Especially at 60 mph ground speed. Above 60 mph and its GMC letters instantly turn to "PIG" (if you know what I mean).. For us, we only do an 8 hour long trip 3 times per year. Thus, we keep its ground speed under 60 mph, and we eventually get there. Works for my family's needs and available time.

    If time or faster ground speed is more urgent to you, perhaps it might we less expensive to "rent" a smaller mini-van, mini-station wagon or rent the car of your dreams - for your long term trips. The "gasoline cost savings" by using a more fuel efficient rental could pay for the daily vehilce rental fees. And, you get to try a different vehicle for long distance travel. Great research opportinity for your future van replacement - when that special time comes. If wondering, my FIL (Father In Law) does that. He keeps his GAS HOG V8 4x4 GMC pickup for local driving and rents a fuel efficient vehicle for his long trips. Works for him....

    Hope this idea helps as well....

  • Thanks again! So far I've been told to check the oxygen censor and to see if the computer is in "Stupid mode" (lol), and to be honest, the van could use some newer tires. I'll keep that tire size you gave me in mind when I shop around for new ones. I hope it helps me! :0)
    P.S~ Would it help out any if I got it in for an alignment? It's off....not real badly, but enough to tell......
  • spike99spike99 Posts: 239
    They say that every "little bit" helps.

    Stuff like:
    - Closer to the ground means less wind drag. If you have a raised van, do lower it back down to factory ground clearance.
    - New shocks on all 4 tires (like Blistien or Rachos HD shocks) to reduce too much up/down movement help a little as well. Especially if pulling a trailer.
    - Smaller / lighter tires means less rubber weight to "get going". Especially if the axle gearing of your van already has "lugging" behavior. Lugging because its gearing is too high - for your road / hill conditions.
    - Pull away "slowly" from the stop lights / stop signs. Let others "wind vacum" your vehicle forward. LOL!.
    - Being slow on those hiway access ramps (like the big loop clover leafs). Today, I no longer bank my van on 2 wheels. Especially on those tighter clover leafs.
    - Less internal weight (like removing unneeded row of passender seats - until needed). My buddy removed his middle row of seats for his dogs. When he does passenger trips, he & his son re-installs his middle seat. Works for him.
    - Using cruise control and set to -3 mph slower then posted speed limit. Same speed as most transport trucks - in my local area.
    - Only use AC when needed. re: The high climate justifies the gas consumption of AC. No more running AC because one can.
    - Wheel aligment / wheel balance.
    - Ensure vehicle has good spark plugs, clean air filter, its thottle body is clean, its injectors are clean, its timing is properly set, etc. etc. Mechanical tune ups do save gas dollars in the long run...
    - Proper tire pressue (as stated on the tire and not in your manual) helps as well. Note: Tire pressure is based on towing and non-towing loads. One lbs rating doesn't fit all brands of tires. Therefore, be prepared to adjust some tires - based on their usage.

    As they say, every little bit helps.

  • joulsjouls Posts: 8
    Hello, I have a GMC Safari van SLT Yr200.

    I was traveling to Alabama and I have the transmission making a shift very rare I have stop at the moment check the Trans oil and I tough it was ok, but next mile it did the same so I stop at walmart and I have added some oil.Service Engine came on and MPG started to go from 19 to 18 and so on until 14.8.
    When I came back home I took it to Advance auto partsand they get the P1870 code " Transmission Slip" they have recomended Lucas product Stop Slip also an oil change.

    Should I change Transmission Filter and O ring? and add Lucas product?

    What else other than engine oil change, air filter, fuel injector cleaning can help to improve MPG?

    I'll appreciate any one can help me, I have this van from original owner and never gave me a problem.

    Thanks, Julio.

  • joulsjouls Posts: 8
    I was having 17.8 and I have replace the following things;

    Spark Plug wires
    Air Filter
    Fuel Filter
    I have make an oil change and replace oil filter
    I have flush the transmission oil and replaced.
    I added a fuel injector cleaner.

    Guess what, I have increased to 25 MPG when I travel from GA to VA.

    But After almost 1.5 years after and continusly changing engine oil and filter I have a transmission problem that I have posted recently and I have bad MPG.

    I'm just hoping that some body can help me too.

  • cobcob Posts: 210
    P1870 is usually the death code so you can plan on a rebuild soon or sell it ASAP.
  • oh jeez! not that! how awful!
    I hope you get that van fixed soon! I've given up hope on my astro and will be trying to sell it soon....I loved that van, it was SO much roomier than your standard minivan and it hauled alot of things, but I've lost the battle with gas prices and can't take it anymore, I'm sad to admit, I'll be looking for a small sedan soon.....curses! :cry:
  • joulsjouls Posts: 8
    How much you think will cost to rebuilt the transmission?

    Is it worthed?

    Thanks for your reply.

  • spike99spike99 Posts: 239
    A few years back, I got the transmisison rebuilt in my 2001 AWD Safari van. Before taxes, it cost $1,200 - canadian dollars. Not too sure how much they charge in your specific region. Might be worth calling a few tranny shops in your area. If wondering, my van lost 2nd and "R" gears. It only has 1st and 3rd. Thus, completed removal and rebuild - with a special kit. Your Astro/Safari van may need the same kit.

    If my GMC Safari van "blew up" tomorrow, I'd probably get a 2007 "demo" Uplander Van. This year has the bigger front brakes, larger size engine and a few other design improvements the other previous GM van models don't have. Demo is around $18K - compared to the $30K of a 2008 models. If I neeed to haul stuff, I'd connect my larger size engine "smaller" mini-van to my 6x10 or 4x6 utility trailer. And when not needed, I'd simply back the trailer into the bush and pull its pin (sort of speaking). Thus, no need for a larger size mini-van (that's a pig on gas).

    Hope this helps - some how.

  • joulsjouls Posts: 8
    Thanks for the info Spike99, I'll try to do everything on my side.

    and will see if I decide to sell or fix this vehicle.

    Have a nice day.
  • cobcob Posts: 210
    I had my 97 AWD trans rebuilt in 2005 for just over $2000 and that was 50,000 miles ago. I have since sold it with the camper we towed behind it and the new owner is still driving it with over 130,000 miles on it. After the rebuild it shifted smooth into each gear and never missed a beat. Make sure you use a reputable repair shop and don't get a remanufactured GM unit make sure they rebuild yours with the upgraded aftermarket parts. The GM reman will be no better than the original trans that failed.
  • joulsjouls Posts: 8
    COB...I just decided to put the vehicle for sale.

    I do not trust in any repair shop near by plus I velieve is not worth for me to spend as you said $2000 usd.

    I'll rather get some money and use it to get a newer car.

  • hi
    Just wondering if you knew about flushing the transfer case? My 99 Safari was hard shifting after a 2 hr highway drive, and we got the transfer case flushed and it fixed it. There is some known issue with it that came out in a GMC bulletin. Most people assume it's the transmission, but it's not.
  • Just got this '97 Astro, 2 WD. Finished a 400 mile trip with about 600 lbs of cargo in the back. 25.3 MPG @ 60-70 MPH!!! Wow!
  • joulsjouls Posts: 8
    Hi GreenSafari,

    Where is the transfer case located? is that the rear axle thing?

    before I made that trip, I took the van to get the seals and bearings replaced on the rear axle, they actually remove and replace the oil.

  • I'd like to know what method you used to calculate this mileage, since it is about 30% too high. I've owned 3 of these vans and never got close to that.
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