$600 to spend on quest for gas milage

04crewvt · Post by **04crewvt** » Sat May 31, 2008 5:05 am

I am on a quest for better gas mileage (who isn't these days). Now that my hubs and brakes are in I am getting about 18.3 mpg highway at 70mph which is darn good but I would love to get it above 20 if at all possible. I was researching buying a more fuel efficient vehicle but to get an extra 11mpg a vehicle would run me about $5000 which would take a long time to recoup the money. Using the stimulus check money to mod the crew seems to make more sense to me if it is feasible.

I currently am running a high flow air filter but the rest of the drive train is stock. I have the HPPIII tune installed for 87 octane and shift firmness along with adjusting for my tire size but no other adjustments. I did replace the cap,rotor and plug wires last summer but am still on factory plugs and did get a P0303 #3 cylinder misfire code a couple of weeks ago so I expect it's time to change them out. I am at 56k I just had the rear diff serviced as well. I have not changed the trans fluid/filter or front diff or t-case fluids yet. I run synthetic oil and have changed the fuel filter every 15k or so both due again soon.

Assuming the tune up as a given for a place to start where would you then spend the money next?

1) performance plugs
2 8mm wires ( I replaced with stock size BW wires last summer)
2) catback exhaust
3)wait4me PCM tune
4) ?????

Post by **HenryJ** » Sat May 31, 2008 6:11 am

The autolite irridium plugs have been doing well and are not that much more than a good stock spark plug.
If it is time for new plugs , that would be my choice. That will cost an additional $12 over the price of the standard replacement plugs.

The stock plug wires are junk, IMO. Open your hood at night and see if you get the leakage light show that I had. If you do have leakage , then upgrading the wires is a good idea. Taylor SpiroPro wires will run $50. That is less than the cost of a stock set. If you show no leakage. Leave them alone. There are not real gains as the stock ignition system is sufficient.

I would install a good free flowing cat back exhaust system. The stock muffler is really restrictive. That may not add a huge difference in mileage, but is your best bang for the buck in a performance modification.
That will be your big investment. I would estimate in the $300 range. Look to a local shop with good experience. They will know what lasts in your area.
Read up on all the good threads on this subject. A single 3" cat back was my choice. Climate and driving habits may change the choice for yours.

Change the fluids in the axles and transfercase. I won't go into the synth controversy. You know if you need to change frequently do to contamination and if the synth makes financial sense. Plan on about $50 here. If you find more frequent changes might be a good idea, think about investing in a rear cover with a drain for the rear axle. Fluids $50 + support cover $150

Spend the money to do a flush, filter and fluid exchange for the transmission. That will run $99-$150 depending upon where you go. Well worth the expense if you have more than 50k miles on it. You can save some money and do the filter change yourself. Then take it in for the fluid exchange. That might save up to $50.

OK, everything done here has done very little to improve mileage. Keeping a good tune and a light foot is the best you can do. Don't be sucked in by claims of better mileage. There are no miracles.

If you fill the list above you have spent over $700. It would take a very long time to recover those expenditures. They are not going to make much difference in mileage anyway. Most are just normal maintenance. The exhaust may add some performance with no loss of mileage.

The best thing you can buy for mileage is a tire gauge and the best thing you can do is spend some time finding the optimal pressure. Play with your tire pressure to get the best wear pattern and mileage.

Use your GPS and check the speedometer. Some of the PCM tuners are modifying the gear ratio and tire size to make their claims of mileage improvement "reality". Don't be fooled. Use your HPPIII to make speedometer corrections. The place for the stimulus check is not in modifications to improve mileage. Those are just fantasies. Put the dollars directly in the tank. Maybe buy a bicycle and use it now and then.

There are no gas mileage miracles out there. Don't get sucked in.

04crewvt · Post by **04crewvt** » Sat May 31, 2008 6:38 am

I am not expecting miracles from snake oil salesmen. I figure the basic tune up as not included in the mod money it's just standard maintenance. I need to do those no matter what else I do since that's the baseline to work from.
I have only wheeled once and the driving I do isn't severe so the fluids will last a long time. I have a good tire gauge and use it regularly. I run on cruise control as much as possible and don't do a lot of stop and go errands. I plan my trips to work with any shopping I need to do and hit the road for anything else very little I would say 90% of my drive time is just commuting about 300 miles a week. I walk around town as much as possible and did get my bike out and tuned up this year for short trips.
It sounds like the Iridium plugs/Taylor wires if needed and then the exhaust is the best bang for the buck it will need to be stainless around here unless I want to replace every 20 months or so.
Until this last round of repairs pretty much everything was still under warranty and I have no payment on this truck so with $1200 into the brakes/rotors/calipers/ rear diff work $175 for the new ball joint last winter and maybe $110 for the new cap/rotor/plug wires (Borg Warner NASCAR Select)) last summer I am doing pretty good on the $ end of this truck. I had already figured another $300 or so for fluids and filter changes this year.

Anybody else with any thoughts otherwise it sounds like the top 3 of my list are the things to price out

F9K9 · Post by **F9K9** » Sat May 31, 2008 6:39 am

I'd go with the plugs that Brule is running for starters. Exhaust might help but, there is $200 minimum spent there. Wires? My best mileage was with the oem wires so, I dunno.

Post by **HenryJ** » Sat May 31, 2008 7:57 am

If you need to retain the SS exhaust, just replace the muffler and stick with the stock pipe. That should cost under $100 installed.
The benefit of larger pipe will be not enough to justify the price of new SS pipe.

Do look at the engine in the dark. Those BW wires may be just fine. Minor leakage can be cured with a coat of cheap hairspray. Clean and spray generously.

Tune it up and spend the rest of that check on important stuff like electronics

bwenny247 · Post by **bwenny247** » Sat May 31, 2008 3:46 pm

might not be possible, but if you can, slow down 5-10 MPH if you're on the freeway/interstate. Aerodynamics take over a great deal whenever you get over 60 MPH.

Torskdoc · Post by **Torskdoc** » Sat May 31, 2008 4:02 pm

get yourself a vacuum gauge and mount it on the "A" pillar. While cruising keep the vac. ABOVE 13" of Hg. The higher the better. My trip meter vs. mpg @ 55

TM VAC
23 13
24-25 14
27-30 15
35+ 16-20

The variances are due to either uphill or downhill inclines. Back off on the throttle when you sense a downhill but maintain enough to keep your speed up. Going uphill, maintain 13-14"(NO LESS) and let the car slow down a bit. DON'T USE the CRUISE!!! It will keep the vac cruising at least 2" lower at a given speed than what you can maintain.

my around town mpg has gone up to 17.5-17.8 by using no less than 13" of Hg while accelerating. And my interstate is now in the 22-23 range @ speed limit of 65. Keeps you in the "Grandma League" but once you get up to speed just maintain it. Use a LIGHT FOOT(u get used to it.) Keep some extra distance to allow for maneuvering to keep from having to slowdown or stop. COAST as much as you can in Neutral downhill. your instant econ mileage will go up drastically while you have foot off gas.

If you're at a long light (a minute or more before green) consider turning off engine.

Pressure up the tires to max allowed by tire manufacturer. Less rolling resistance. Ride will be harsher and possibility for loss of control increases so be careful.

Take all extraneous weight out of truck. Clean out the bed, back seat, under seats, remove spare if all your driving is local AND you have someone at home that can bring it out if you have a flat. EMPTY THE TRUCK OUT.

Don't idle after startup anymore than absolutely necessary. Just enough to get started and fluid pressures up then take off moderately.

After awhile you'll be able to refine your technics and maximize your mileage while driving ANY CAR.

Larry

04crewvt · Post by **04crewvt** » Sat May 31, 2008 4:04 pm

I could slow down some but I then risk more problems from the other nuts on the road. At 70 I am passed by almost 60 % of the cars on the highway. I had to block traffic a couple of weeks ago to help get the tail gaiters off the bumper of an ambulance running lights and sirens to the local hospital.

Post by **HenryJ** » Sat May 31, 2008 4:06 pm

Torskdoc wrote:get yourself a vacuum gauge ... your instant econ mileage will go up drastically while you have foot off gas.

ScangaugeII does that for you with the MPG readout.
That might be one to spend some money on. It really is a handy tool.
They are marketing it as a gas saver.

Clearing a code on the fly is priceless. I have read codes and cleared them enroute. Gotta love that.

04crewvt · Post by **04crewvt** » Sat May 31, 2008 4:15 pm

I do shut off the engine when stuck for a train and when it's safe to do so in traffic, I do carry a lot of stuff for my C.E.R.T activities as well as a tool kit in the truck all the time but by far I alone add most of the weight to the truck. I have a vac gauge around somewhere that I never installed since the 2004 pillar is a different shape than the previous models and I never found a pod that would fit ,I might have to try to find one again or I could get a scan gauge if that is one of the possible parameters it can measure. I run my tires at around 40 PSI cold in the summer so I am good there. Loss of control is no problem I have spent most of my mod money to this point on suspension upgrades. I was one of the special people who only got an emergency donut for a spare so no real savings there.
Thanks for all the ideas everyone keep em coming.

04crewvt · Post by **04crewvt** » Sat May 31, 2008 4:19 pm

How far out from the dash does the scanguageII plug sit when plugged into the OBDII port? I don't have a lot of leg room as it is and would hate to pick one up and not be able to use it. If anyone could measure that would be great.

Torskdoc · Post by **Torskdoc** » Sat May 31, 2008 4:24 pm

I do speed limit and laugh at the next exit when actually catching up to the idiots that are speeding up and slowing down constantly, by maintaining a constant speed. 70 vs 55 will cost you a few mpg and only saves you 1-2 minutes on a 10 mile trip. I drive an interstate everyday for 11 miles twice a day driving my kid to work and back. It used to take me 13 minutes and mileage was low teens @ 70+ keeping up with traffic. @ 55 it takes me 17 minutes on avg and I get low 20's mpg. Just stake out the right lane and let the idiots do what they want. you will get used to it.

Brule: Remember back in the 70's a vacuum gauge called "the economizer?" Sunpro is bringing it back. a vac gauge with a rescaled face with bad, poor, and good (0-8 bad,9-15 poor, 16-24good or something like that.) I have a 2" vac. Gauge in a pod @ eye level on the "A" pillar which is easier to read than the T.M. or even the cluster.

04crewvt · Post by **04crewvt** » Sat May 31, 2008 4:33 pm

Once I get the tune up done I will give 65vs70 a shot and see what it does for me. That wouldn't hurt my drive time much in good weather and if it gives me another mile per gallon that would be great. Would any shift point tuning help with MPG? I have never messed with the factory shift points using my HPPIII just adjusted for firmer shifts.

Post by **HenryJ** » Sat May 31, 2008 4:40 pm

04crewvt wrote:How far out from the dash does the scanguageII plug sit when plugged into the OBDII port? I don't have a lot of leg room as it is and would hate to pick one up and not be able to use it. If anyone could measure that would be great.

At most 1/2" from the OBDII port. barely lower than the shield that is already up there. If the ebrake pedal is a problem, then you might have an issue

I don't think it will be a problem.

04crewvt wrote: Would any shift point tuning help with MPG?

Nope. Mainly WOT. You can get it to quit searching for OD on hills with a lower shift point, but that is not going to help mileage.

Torskdoc · Post by **Torskdoc** » Sat May 31, 2008 4:43 pm

I don't see that it would unless you're flooring it from 0 to 65.

04crewvt · Post by **04crewvt** » Sat May 31, 2008 4:54 pm

Sounds fun but it's not how I usually drive, fast getaways are not in my future. I actually bug people because I yield to traffic already on the interstate when I merge instead of cutting off whoever might already be there. The only place I do accelerate firmly from is stoplights, even then I usually get blown away by someone in the next lane.

04crewvt · Post by **04crewvt** » Sun Jun 01, 2008 10:45 am

ScanGaugeII on order. I will be checking prices on fluid/filter exchanges tomorrow with my local shops as well as pricing a high flow muffler. I will check if they can get the autolite xp plugs as well. While I could get them cheaper myself I can have them do it all at the same time and have no down time. I will post results when I get everything done.

Post by **HenryJ** » Sun Jun 01, 2008 11:23 am

A couple things I just thought about.
Buy a can of SeaFoam TransTune. Add that to the transmission the day before you take it in for the trans service. It is a good varnish breaker. I would not run it all the time, but I do use it to loosen everything up prior to a filter and fluid change.
Hopefully you have been adding that maintenance dose of injector cleaner every other oil change. Might be a good time to grab a bottle and run a tank of treated fuel prior to all your mods.
Keep us posted as to the mileage of that tank and the one after all the modifications.
You are going to love the ScangaugeII. It will be fun to see if you can actually alter your driving to maximize the mileage. Be sure to add your thoughts to the Scangauge thread.

04crewvt · Post by **04crewvt** » Sun Jun 01, 2008 11:30 am

Thanks Brule,
I will look for the SeaFoam this week. I do run injector cleaner every 3k or so it's the Amsoil brand and I know it's time for an oil change when I run out (I buy a years worth at a time since I only change the oil annually). I aways note the MPG from each tank so I will try to post that one and the one after to see if anything changes and will definitly post on the ScanGaugeII when I get it in.

F9K9 · Post by **F9K9** » Sun Jun 01, 2008 2:42 pm

I am sure both differentials are due to be change. You can do that yourself easily enough. I'd look at synthetic fluids as a replacement. It will buy you a very slight improvement. Whether it is worth the additional cost is debatable.

04crewvt · Post by **04crewvt** » Sun Jun 01, 2008 2:51 pm

Rear was just done with the axle seals a couple of weeks ago. I have been debating synthetic for them but I need to see how difficult it would be to do in the driveway or if I can find a local place that uses Amsoil since that's what I want to run if possible, same with the transmission. I expect the rear will get a cover with a drain and go synthetic the next time it gets changed.

Post by **HenryJ** » Sun Jun 01, 2008 3:15 pm

I'd pass on the synth if you have the G80.

04crewvt · Post by **04crewvt** » Sun Jun 01, 2008 3:17 pm

No G80 here unfortunately, even though it says all 3.73 rear axle ratios got it mine has the 3,73 but no G80 another thing missing from the last of the crews I guess.

Post by **HenryJ** » Sun Jun 01, 2008 3:19 pm

Synth that sucker when you get the chance!

Might as well get your moneys worth out of the recent change though.

F9K9 · Post by **F9K9** » Sun Jun 01, 2008 4:35 pm

There is no hurry unless you are ready to change the front diff fluid and it is as easy as an oil change. I really do not think synthetic in the tranny is a good idea but, I have no personal knowledge.

Post by **HenryJ** » Sun Jun 01, 2008 5:05 pm

f9k9 wrote:I really do not think synthetic in the tranny is a good idea...

Me either. Anywhere clutches and friction might be needed is a bad place for synth.

04crewvt · Post by **04crewvt** » Sat Jun 07, 2008 5:32 am

Well I got part of the list done on Friday, the truck has all new fluids in transfer case, front diff, transmission with filter, fuel filter, Autolite iridium plugs and new wires, I SeaFoamed the trans before they changed fluid. Trans seemed to shift smoother on the way home we wil se if it had any effect on mileage. ScanGaugeII is in and should be installed this weekend. I will post more on that over in the other thread.
That was the good stuff now for the not so fun stuff, no muffler yet they ordered 2 to see which would fit with stock pipes and didn't get it right. They found that 2 of the spark plugs had been cross threaded from the factory so they had to drill and helicoil them to put in the new plugs and worst of all while doing that they found the lower intake manifold is starting to leak with repair in the $700.00 range

This puts me at right about $2500 for everything, not great for a truck with 56K on it. I hope to have the new muffler and intake work done next week but we shall see.

Post by **HenryJ** » Sat Jun 07, 2008 5:37 am

Are you still running Dex?

As some consolation, I figure a vehicle is a bargain to drive for $1000 per year in maintenance. That leaves you another $1500 to still be in good shape.

Where / how did they find the intake leak? Those are usually not very apparent unless you are specifically testing for them , or they are leaking badly.
If the coolant is on top of the manifold, it is just the thermostat or hoses leaking. Many are familiar with the intake issue and assume they all have this issue. Prior to 2000 it was common for those running Dex. After that not as common. I am always skeptical. I just don't want someone trying to take advantage.

04crewvt · Post by **04crewvt** » Sat Jun 07, 2008 5:45 am

Yup - And it looks pretty and clean with no sludge and still is apparently crap for this motor and of course my truck doesn't fall in the range where it should be covered under the lawsuit. It will be flushed and changed to green when the work is done that's for d_mn sure.
As it is I have only spent around $400 for tune up and repairs since I bought the truck and it was only around $150.00 out of pocket when I bought it and this repair is mostly covered by the workers comp money I just got in from my knee settlement, I really will only have about $1500.00 out of pocket not including regular maintenance and mods in the 4 years I have owned it.

Post by **HenryJ** » Sat Jun 07, 2008 5:54 am

You are sitting pretty good still. It is a big chunk to fork out all at once, but this will add the longevity and reliability.
Hind sight will be 20/20. I think the investment will be one well spent though.

04crewvt · Post by **04crewvt** » Sat Jun 07, 2008 5:56 am

If I had a payment as well I would be in bad shape but since I own it outright it is still better to fix than trade that's for sure.

Post by **HenryJ** » Sat Jun 07, 2008 6:01 am

How interested are you in pursuing the intake leak problem with GM customer service? If you bought the truck new , you might consider seeking a "good faith" repair. Customer satisfaction is important and you may be able to have the "known problem" as evidenced by the settlement, repaired under their "good faith" policy.
This may take some time, but it has worked in other cases. You do have a solid footing in that you are having a repair facility diagnose and repair and the settlement for this exact issue has just been finalized. If you want to expend the energies, you might just get it taken care of free of charge.

04crewvt · Post by **04crewvt** » Sat Jun 07, 2008 6:12 am

I purchased the truck "used" with less than 7000 on the odometer. I could pursue with GM but would I be better off having them do the repair if and when it gets through all the paperwork or fix it now and hope they will reimburse later

Post by **HenryJ** » Sat Jun 07, 2008 6:25 am

If there is indeed a problem, fix it soon. The internal damage may be occurring. Engine oil will not look gray as most think. It will be brown and slightly opaque. the sludge will be building in the intake manifold.

I would make a call to get a case started. I would also write a letter and mail it as well, citing the case number and contact person with customer service.
Mention that you are a loyal GM customer and wish to remain that. Cite the recent GM settlement for this exact issue. State you are seeking a repair at their cost under their good faith repair policy. Thank them for their time and be sure to ask when you should follow up on this case if they do not provide you with a time they will respond.

04crewvt · Post by **04crewvt** » Sat Jun 07, 2008 6:32 am

Sounds like I call the dealer and have them fix it so it's easier to get money back. I don't want to wait too long to fix and they might be more willing to help if they fix it. I will call the dealership on Monday and see what they say, how much they want to do the job, and get a case started.

04crewvt · Post by **04crewvt** » Sat Jun 14, 2008 6:59 am

Update- Just put 200 miles or so on the trip down to my parents place on wednesday night. Average speed 51 according to the scanguage much of the trip on the interstate and thruway at 70, average mpg 18.5. Still no exhaust work. I checked out the factory plugs they had marked the cylinders where they came out of, the #3 that was misfiring had it's electrode burnt down pretty good and they all were over .060 on the gap most were showing signs of running a little hot. We will see if the irridum plugs work out better. I hope to get the exhaust and intake work done in the next week or so once I get back home. Dealership quoted me $500 for the intake gasket so now I have to see if I can do better than that with the place I have been getting the rest of the work done.

Post by **HenryJ** » Sat Jun 14, 2008 7:13 am

Do you have a precat? Do you have visual emissions equipment inspections?
The precat has been a problem source. If you are in for the exhaust work, removal may be something to consider?

04crewvt · Post by **04crewvt** » Sun Jun 15, 2008 5:11 am

We have a visual emission test in vt but I am not sure if the pre-cat is required. Right now it looks like the best price for the intake work is at the dealership, since the percat is still under warranty I will have them check it out at the same time. If I do go to my other shop I will see if they can remove it.

Post by **HenryJ** » Sun Jun 15, 2008 5:43 am

If you have emissions testing and a visual inspection, removal will not be an option. The muffler shop can drill tiny holes before and after to measure the pressure difference. Too much will require replacement. The dealer will not be able to do this would be my guess. I would not bring it up until a muffler shop has confirmed it.

There is another option requiring lots of work on your part to cut the pipe and pull down the cats, then replace the assembly. I am going to assume that is not within the scope of what you prefer to get into.

drperry · Post by **drperry** » Wed Jun 25, 2008 5:45 am

How much does a stock crew cab weigh?

My Blazer tips the scales @ about 4200lbs.

With factory rubber, at 74 MPH, I was getting 24 MPG.

You should be able to break 20, easilly enough.

I got 18 MPG on the last highway trip with my 30x9.5" BFG A/T's.

They're a heavy tire... 7 lbs heavier than stock.

04crewvt · Post by **04crewvt** » Wed Jun 25, 2008 5:45 pm

Curb weight is listed as 4083lbs, add all the hardware I have added, my tools and me and it's pushing 4700lbs. My driving has lots of highway driving on hills so quite a bit of downshifting to keep speed even. I have broken 20 on a couple of long highway runs but average between 17-18 at best in my daily driving. My 95 blazer with similar payload would consistently get 20mpg as well and that was with close to a quarter million miles on it. We will see what happens once the intake gasket is fixed and the new exhaust system goes in on the next week or two.

drperry · Post by **drperry** » Wed Jun 25, 2008 6:05 pm

Depends on which gears you have too, I think... Though, you probably have the 3.73s...

04crewvt · Post by **04crewvt** » Wed Jun 25, 2008 6:09 pm

3.73 were in both, no G80 in the crew but it was in the Blazer after the rear was rebuilt. My first S was a t15 Jimmy with the 2.8L and 4.11.s and I got 16-18mpg with that with lots of drive line and engine mods.

drperry · Post by **drperry** » Thu Jun 26, 2008 1:39 am

My Blazer has 3.42s...

Mabye the Blazer is more aerodynamic?

04crewvt · Post by **04crewvt** » Tue Jul 08, 2008 3:49 pm

Internal coolant leak was fixed today, another $530 into the crew. Unfortunately they flushed and replaced the coolant with Dex again. I had asked for green and it was even on the work order but in there rush to get it running for me by the end of the day they must have missed that part or didn't want to do it ( not done at the dealer ). I hope this gives me a little better numbers, this last fill up I was at 15.1 engine seemed to be bogging down a bit. I will give it a tank full and see where I stand. Next step muffler and gut the precat if they will do it and if they remembered to take some measurements today to see what will fit with the stock stainless pipes.

S-10CREWCAB.NET

$600 to spend on quest for gas milage

$600 to spend on quest for gas milage

update