Cramer Posted September 6, 2011 Report Share Posted September 6, 2011 A few things you can do: - tune tailored towards fuel economy. Most people tailor their tunes to improve WOT performance using 93 octane. From what you're saying, it sounds like you will want to run 87 octane. I wouldn't expect much of an improvement in WOT performance with a tune (87 octane) and probably marginal gains in part throttle power/fuel economy. If a tuner spends the time on the dyno and focuses on fuel economy they can literally (cell by cell) optimize the torque the engine makes in a given part of the map by adding or removing a degree or two of timing (if the engine needs it) and improve economy. Absolutely can! Problem is, that takes a ton of time and the tune is going to vary with different engine/truck combinations (gearing, tire size, engine size, mods, etc). In other words, a tune that is optimized for you might have some knock on another person's truck even though that persons truck is pretty close in comparison to yours. For that "little bit" of power or efficiency no one is going to do it. It doesn't pay. Point is that you can improve your economy with a tune that is optimized. There are also other things a tuner can do like a "lean cruise" strategy where during an extended cruise condition, the vehicle will go into open loop and the computer will lean out the air/fuel (typically up into the mid 15:1 range instead of 14.7:1). For the average tune you will buy, I'm sure you can expect maybe a mpg improvement, maybe a little more. Every little bit helps I guess. Torque is going to get that heavy truck moving. The easier you can do that, the less you have to push down on the gas and the better economy you will get. Gearing, engine size, efficiency of combo (bolts like headers, cai, electric fans to reduce drag, etc) and obviously tune will affect this. I had a 2000 silverado ext cab 2wd with the 16" aluminum wheels, stock size tires, 3.73 gear and 5.3 engine. If I drove it easy (no jack rabbit starts mainly) I would get 17 mpg in the city! That was light stop and go traffic with speeds averaging around 40 mph. If it was heavy stop and go, I would drop down into the 15.5 - 16 mpg range. On the hwy, I would see 20mpg driving 70-80mph. I had drove it a little slower (60-75mph) and averaged 20.9mpg. I'm sure it could get 21-22 if I drove 50-55mph. Another reference my buddy with the same basic truck except it had a 3.42 gear got 22-23 driving 55-60mph. Note this is driving in light traffic conditions (out in country). If you're constantly speeding up or slowing down because of the traffic that number would drop a bit. For you, probably a tune, a lighter tire/wheel combo, tune up, and all of your bolts ons. A "beater" might be right up your alley if fuel is killing you that bad. Just saying...A 4.8 will (in theory) use less fuel then other engine combos, but if it takes more gas pedal to get it moving at the rate you desire then you might end up using more fuel then say a 5.3 or a truck with a steeper gear. Maybe you should do a blower like a TVS1900 mod. If you can drive it easy, you will usually see that it takes less pedal to get the truck moving now (plus the blower can increase the engine efficiency) and you will save fuel. Problem is, only about .002% of the population can drive it that way Good luck and sorry for the novel You took the words out of my mouth. Economy tune in person, or someone like Zippy who can set you up with lean cruise and everything. Smaller wheels and or lower rear gear ratio. Proper maintenance to the motor and trans, along with correct tire pressure. Get a different daily driver. I am averaging 19mpg on the highway with a rich tune, and that is at 55mph. At 65mph I average just over 20mpg. In town It is down to 14-15mpg. Quote Link to comment Share on other sites More sharing options...
Sik-rod-yo Posted September 6, 2011 Report Share Posted September 6, 2011 vespa and done lmao Quote Link to comment Share on other sites More sharing options...
f1ss Posted September 6, 2011 Report Share Posted September 6, 2011 vespa and done lmao wat u talking about? Dk General Lee bmx bycycle and unlimited gas milage! Quote Link to comment Share on other sites More sharing options...
Sik-rod-yo Posted September 6, 2011 Report Share Posted September 6, 2011 wat u talking about? Dk General Lee bmx bycycle and unlimited gas milage! Shape ups non said Quote Link to comment Share on other sites More sharing options...
f1ss Posted September 6, 2011 Report Share Posted September 6, 2011 Shape ups non said true, i was just clowning around bud. Quote Link to comment Share on other sites More sharing options...
chpspecial Posted September 6, 2011 Report Share Posted September 6, 2011 Fyi, 4.8l truck do not have very conservative tune like the 6.0 and therefore a tune will give very little if any gains sent from my thunderbolt Quote Link to comment Share on other sites More sharing options...
jddmj Posted September 6, 2011 Author Report Share Posted September 6, 2011 Thanks guys for the help. I will be doing a tune once my wallet situation allows. Also, I just sold the DD I did have because of the safety issues. I'd rather pay a little more and have that bit of insurance of having a larger vehicle. I just dislike the idea of being out so much just to make it into work LOL Quote Link to comment Share on other sites More sharing options...
misterp Posted September 6, 2011 Report Share Posted September 6, 2011 I think you need to first look at what's realistically possible with your truck (MPG-wise). Several guys here with 2WD trucks are getting 21-MPG freeway, and MidnightRidr also got 21-MPG freeway in his truck as well so I am going to say that's about the best that's possible... will going from 17 to 21 MPG be enough of an increase for you? If it is, then what you will have to do is swap the 4.8 for a LQ4 or LQ9, install headers & catback, a radix, a tonneau cover, a premium 2600-2800 converter, cam, and a PCM tune because *each* of those trucks has exactly that combination. You *may* be able to get this kind of economy without the blower. The 4.8L is killing you IMO, every 4.8L equipped truck I've seen has had worse running economy than the 6.0L. By the time you put all that money into the truck, it just isn't worth it. Mr. P. Quote Link to comment Share on other sites More sharing options...
eeekroar Posted September 6, 2011 Report Share Posted September 6, 2011 Two Words!! SMART CAR Quote Link to comment Share on other sites More sharing options...
jddmj Posted September 6, 2011 Author Report Share Posted September 6, 2011 Two Words!! SMART CAR EEK, If I had a smart car it would look like I was wearing it. 17-20 would be good. I travel a fairly level highway with a speed limit of 55 mph. I thought about going and test driving a Cruze Eco, but I doubt i would trade. Small cars scare me after my brothers wreck in his full size. For those that don't remember And all this damage was done with a s10. God had him in his hands during this. But I just feel more safe i the truck. I just want to squeeze what I can out of what I got. I cant afford an engine swap. I think a tune would finish the job up for me. Quote Link to comment Share on other sites More sharing options...
T-Bag Posted September 6, 2011 Report Share Posted September 6, 2011 (edited) When I switched to Royal Purple I gained about 1mpg on average. Motor and diff. oil. Also, weight reduction. Lose the spare, spare hanger, hitch, under back seat jacks, iron, clamps etc. This may help. Helped a little for me... Edited September 6, 2011 by Bad Ass Silvy (see edit history) Quote Link to comment Share on other sites More sharing options...
8hnpSS Posted September 7, 2011 Report Share Posted September 7, 2011 17 is great my yukon averages 13.9 i wish i was even near that Quote Link to comment Share on other sites More sharing options...
misterp Posted September 7, 2011 Report Share Posted September 7, 2011 You can get a GOOD 3-piece GM OE tonneau cover from gasemall for *dirt cheap*; that will get you +1 mpg at speeds over 40 MPH. Get a good tune in the truck, that will gain you efficiency everywhere. Run a good tune on premium gas, even though the fuel is $.20 more per gallon if you can get 20-MPG @ $3.79/gal it will be 11% cheaper than 17-MPG @ $3.59/gal. Make sure you are running a MPG-friendly tire and keep them properly aired, that is usually a MPG culprit. It appears that above 72-MPH the aero properties of this truck really starts to drag bad, don't drive more than that (75-mph tops). My own truck's MPG sweet-spot is 65-72-MPH FWIW. These motors are designed to be most efficient cruising at 1800-2100 RPM, I would try to keep cruise RPM 1800-1900 RPM. Consider having catalyst overtemp (in your PCM tune) raised to 76-MPH or higher. Do get a set of GM efans and get rid of the clutch fan, that's +0.2-mpg. Consider changing your motor oil to Mobil1 0W-40 Diesel Truck oil, I run it in my own truck and saw a MPG improvement as well as 10-degree drop in oil temps - this oil has thinner base stock (more efficient to pump) and higher ZDDP additive so protects well at temp, I recommend a Mobil1-206 filter but that will not affect mileage just engine longevity; Royal Purple guys say they get better MPG on that oil too. In your PCM tune, the converter lockup strategy will be KEY to economy, if it's not thought-out well and the converter is kicking in & out of lockup that will waste a lot of MPG so address that in your tune. Those are all the 'cheap' ideas I have to help you with your MPG quest. Headers will help a tad but that's a big investment that I personally would not do on a stock 4.8L motor. If you want to spend money on the motor I would seek a good performance camshaft & new timing chain, mild street cams gain efficiency as well as a few horsepower and you can use that efficiency to save MPG. Mr. P. Quote Link to comment Share on other sites More sharing options...
Bad Bowtie Posted September 13, 2011 Report Share Posted September 13, 2011 Royal Purple trans & dif fluids, new AC Delco O2 sensors, new AC iridium spark plugs. Quote Link to comment Share on other sites More sharing options...
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