Old member returning, looking to improve 2002 Yukon XL MPG

[YukonCornelius]

Hey guys, it has been a while since I've posted. If anyone remembers me, I had a Cadillac CTS-V that was getting some impressive numbers about 5 years ago.

http://ecomodder.com/forum/showthrea...mpg-22967.html

http://ecomodder.com/forum/showthrea...0-a-24034.html

I sold that V this year and picked up a newer, supercharged V. 6.2L. low compression, 4000 pounds. It gets horrible fuel economy. So does my 02 Yukon, which I drive much more. I work from home mostly and my fuel bill each month is still around $360-410. So I thought, it's time to get back into ecomodding, starting with the Yukon.

I still have the Cavalier. It's over 300,000 miles now, getting tired, rusty, and I don't feel all that safe driving it.


My best full tank with the Yukon XL is 15.5 in warmer weather. My Worst is 12, I'm averaging around 13.5 in the cold. I took out the stock airbox and installed the old homemade cold air intake off my old CTS-V, this seems to have really hurt me. Feels like I lost a sold 1 mpg, just a feeling. I'm going to put the stock airbox back in and do a hot air intake for comparison.

I've already got the tire pressure up around 45psi per wheel.

The gearing is the lowest numerically available, diff fluid is new but not synthetic (previous owner)

I took the 3rd row out for space.

The spare tire is missing (free weight savings! lol)


My question is, anyone with a similar vehicle have some changes that made a "big" improvement?

As of right now, I'll go bear the cold and do the hot air intake. I also have a full set of Iridium plugs that I had for another LS car which I will put in at some point.

My goal is a full tank at 23MPG. I feel that would be a solid improvement over the EPA 18 highway.

[rmay635703]

My c-code NA 6.2liter diesel 2wd 1989 suburban with 2.8 rear and a 5 speed shift was flirting with 30mpg at 50mph before all the lines and tanks rusted through.

Besides a stick shift, running a little lean and old 1970’s airplane gears there isn’t much to do beyond a basic tuneup, properly sized and rated tires and possibly some very basic aero mods there is likely not anything dramatic
To do with old iron.

[YukonCornelius]

Took the spark plugs out and based on my years of wrenching, these plugs and coil wires were original. 15+ years and 170,000 miles. The gap was double the replacements, AC/Delco Iridium. They looked like something off the Titanic. I'm surprised one didn't snap off.

It ran so well on those shot plugs. Low throttle power is better now. I almost feel like I've got less top end but who knows, might be better low and mid-range deceiving me. Also found and replaced a broken ground strap. (headlights are brighter now). And I bumped the tires from 35 to 45 psi.

Might do a grill block next.

[rmay635703]

http://ecomodder.com/forum/showthrea...mpg-33961.html

If you need some v8 inspiration, take a look above.

Also the 93 2wd 350 v8 Suburban i once had would return around 21mpg driving reasonably on the highway.


Another thing, if you can restore your rig to epa that’s a pretty huge jump by 15%, small MPG increases on these rigs are actually big gains.

Good Luck

[wdb]

Air dams make a big difference on big iron with big gaps between the bumper and the ground. Plenty of examples on here. I think there's one made with industrial rubber belt material, that sounds like just the thing for your rig.

[elhigh]

+1 on the air dam. Self drilling screws (or better, bolts through holes with fender washers on both sides) through some fender washers to hold angles, fender washers on both sides on bolts through baler belting and angles. Take maybe an hour.

Try a warm air intake instead of cold.

What kind of instrumentation do you have aboard for tracking performance?

[YukonCornelius]

That Caprice is an incredible rig! I wish this Yukon had a manual trans, it probably isn't a difficult swap but I wouldn't consider something like that unless I was dealing with a trans failure.

An Airdam would be final step for me. In my case, it is something that likely would get damaged.

I don't have any instrumentation in it to monitor MPG, but I'm guessing that since I was last active there are new/cheaper options to interface with the OBDII system.

I just installed my grill block. I wrapped it with the transparent stick on carpet protector I have a roll of. Contractors use it to protect floors.

[cRiPpLe_rOoStEr]

Originally Posted by Lbar

I wish this Yukon had a manual trans, it probably isn't a difficult swap but I wouldn't consider something like that unless I was dealing with a trans failure.

If you ever swap a manual transmission into the rig, I'd recommend you to also consider replacing the pedal-activated parking brake for a lever-operated setup.

[elhigh]

A Scangauge II should hook right up to your Yukon. It just plugs into the OBD port. An even cheaper option is a Bluetooth adapter for the OBD port and t h e Torque app on your phone. They each have their quirks and limitations. I've used Torque with some success. For instance, it gives me coolant temperature that is otherwise not provided at all in a Prius, and only vaguely indicated in a HCH1. That's nice to have when you're experimenting with grille blocks. Of course where you are at this time of year overheating is probably close to impossible without shooting the rad full of holes, but when the weather warms you may be able to extend the grille block's season, or even leave it in place - or most of it - permanently.

[YukonCornelius]

https://www.autometer.com/ecometer-ii.html

This looks interesting. It can be picked up for $75 on Amazon prime.