Improved fuel economy?

[east302]

Also what kind of mileage are you getting?

Seems to be a reasonable question, for all we know he gets 20-mpg, lol.



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[94burbk1500]

So a quick summary, exhaust (headers?, crossover, replace oe cat) Intake, tune up (plugs wires etc.), reduce drag (brakes, fresh fluid in diff, repack front bearings,).Aero maybe? Like the splitter under the front bumper? If you want to get radical maybe you could regear for your driving style. Also what kind of mileage are you getting?

I average 15 highway, 12 city

 

[Spookers]

Not lugging the engine helps, meaning having the proper gear ratio for your target speed I had 3.08 and switched to 3.73 and got 2mpg better, with 3.08s it revved at 1700 at 60mph and maintaining speed had a slight chug to it most noticeable up hill (really noticeable at 50mph) with 3.73 it was at 2000rpm and didn't chug
Keep tire pressure up
Set base timing at 14* (really reduces chugging and gives it more throttle response )
Check that the gasket in the injector pod isn't leaking ( the split line should not be wet)
Set the fuel pressure at 14psi
Swap to electric fans (jegs has a nice universal set for about $40)
The dual snorkel air filter housing to get cooler air (can start by drilling the rivets out of pre heater flap and closing the hole off )
Try anything that reduces rolling resistance like running narrow tires at as high of pressure as recommended, checking wheel bearings, low drag callipers etc.
Aero mods could help a little, start with the factory air dam on the front bumper, if possible lower the truck a little, have heard of people try using thin foam weather stripping around headlights, using sheets of plastic or aluminum to "flat floor" the bottom of the truck

 

[Deathpunch0311]

I have 305 70R16 Mud Terrain Toyos on my 1995 350 CID Extended Cab Z71. I went from 10.4mpg to 12.6 highway by increasing my tire pressure. It was 35psi but now I'm running 45 to 50 if I recall. I think the max is higher still. Anyway, saw a significant difference FYI. I wont be happy until I get around 16mpg. I drive 70 miles a day to work round trip. I like the mudders but going to go more streetable and a bit smaller when these wear out to try to save some money on fuel. This is just to say that tire pressure can have a big effect.

And I thought I was getting bad highway mpg. Lol no offense.
I have a 98 k1500 lifted 6” on 305/65r18 falken at3w all terrains with 3.73 gears and I get 14.5 mpg at 75mph.
Around town 10-11mpg
My wife’s 2013 2wd ram 1500 with the 5.7 hemi gets the same exact MPG.

Spookers is right. Gearing has ALOT to do with mileage. Tires size and profile (mudders get worse mileage than all terrains). Extra weight how you drive etc

But hey we all know someone that knows someone that read somewhere their second cousin got 22mpg with a GMT400 on the highway at 90mph HAHA

 

[DerekTheGreat]

...Best bang for the buck TBI fuel mileage and low-midrange power modifications I found were small 1 1/2 or 1 5/8" diameter long tube headers into dual 2.5" pipes into a 2.5-3" merge Y into a high flowing 3" exhaust with a straightflow muffler followed by ECM chip work. I also found running 13-14 psi fuel pressure to help atomization and torque which keeps you out of the throttle. Finally I also ran 25% underdrive pulleys with no ill effects. I had a stock 8.75:1 1-ton 350 TBI crate engine in my old 1983 G20 van. Backed to a 700r4 and 3.08 gears. With 1.6 full roller rockers, doug thorley tri-ys, merge Y, high flow cat, 3" single in/dual out magnaflow, edelbrock 3704 intake, open center TBI spacer with a 454 TBI unit and 454 air cleaner assembly it was a completely different engine. I would average 14 mpg city and 20 mpg highway with lean cruise enabled at 16:1 air/fuel ratio on level road at 70 mph. At light throttle, steady cruising speeds I had lean cruise coming on as low as 30 mph (emissions dyno tests were done at 15 and 25 mph)

You wouldn't happen to know what the stock strategy is, would you? I'd like to know if these things have a lean cruise from the factory. My truck is a 1989 K1500, 350, 5 speed with 3.73's. I know our old '88 had a lean cruise signal on the trans, so says the service manual. THat was a 454 TBI with the dump truck SM465.

 

[RichLo]

lean cruise control generally didn't come into play until the generation before cylinder deactivation. However, I think I heard of astro vans in the late 90's having lean cruise?

 

[Deathpunch0311]

lean cruise control generally didn't come into play until the generation before cylinder deactivation. However, I think I heard of astro vans in the late 90's having lean cruise?

Whats lean cruise control?

 

[DerekTheGreat]

The 454 had it, but used a switch to signal to the ECM that it was in top gear. I can't find any information as to what else it uses to determine when it can/will enter lean mode and how much it actually leans the mixture to. Best that turd did was 8 mpg which I don't think was too terrible given it had 4.10's and no over drive.

But as for my '89 which is a different animal with it's 350 and overdrive trans I do not see any such information about a lean signal or switch for OD. The GM fuel infection book I have for '88 doesn't mention anything about how lean the thing runs when cruising or a lean mode for it either. That's what I'm curious about.

 

[RichLo]

Whats lean cruise control?

When your cruise control is off, it operates like normal targeting optimal air/fuel ratio for best performance. But then when your cruise control is activated it leans out the air/fuel ratio because it just has to maintain speed. To have this feature, your stock vehicle needs to have a special PCM, wideband 02 sensor, and other things I'm sure. As far as i know, you cant retrofit a vehicle without one, it has to come from the factory that way.

 

[L31MaxExpress]

This thread has ALOT of bad information regarding lean cruise on GM applications. I have yet to see an OEM calibration inside the US with the lean cruise enabled from the factory although many ECMs and PCMs have the coding to run it. I have seen Export vehicles such as Holden and GM Mexico calibrations have it enabled. They do not use any form of a switch and also do not require cruise control for it to enable. It is usually MPH and MAP based qualifications. If you are above say 40 mph and below 70 KPA MAP the lean cruise will activate. When it activates it disables the 02 sensor by switching to Open loop, then commands an air/fuel ratio that is leaner while advancing the timing at the same time. If you are tuning your own chips or flashing your own Gen3 PCMs it is actually fairly easy to enable. On my Express van I was able to enable lean cruise in the 0411 that Holden used in Australia. You can set your AFR to whatever you want it at. In the 30-50 kpa range I run 16.5:1, 50 kpa 16:1, 55 kpa 15.5:1, 60 kpa 15:1, 65-80 kpa 14.5:1, and 80-100 kpa 14:1. I set it to work like a power valve and make it richen up at higher loads so that I do not have to exit lean cruise under higher loads. At the lower kpa ranges I add as much as 8* of timing to keep the engine responsive because that is what my setup likes. On flat land at 70 mph, with 5.13 gears and 31.5" tall tires with the 4L80E, I am turning 2,850 rpm, running about 18% throttle and a MAP reading of 45-50 KPA.