swathdiver

I've read that the Gen V 5.3 motor stays in V4 about 50% of the time on gasoline. These make about 44 horsepower per cylinder and on E85 over 47 hp per cylinder. Custom tuning may eke out even more performance. My Gen IV 5.3 does really well mpg wise between 20-30% alcohol content, better than on gasoline according to the last 4 tanks of fuel. Power wise, it loves 80% and gets 2.82 mpg less than gasoline for an average tank of fuel.

Did you pull the ABS codes that set off this light and if so, what was it? A bi-directional scan tool like the Tech-2 is needed to properly bleed the ABS system. There's no doing it without one properly.

Never found first hand accounts when doing my homework before buying one. A fella bricked a module the other day because he let his battery die, did not follow instructions. I wonder how much of this gets blamed on the less expensive Tech-2s? My Tech-2 can barely speak with our Pontiac Montana but works perfect on the Yukon and Impala, it's the old Montana with the problems.

You can get a Tech-2 these days for about $350. The latest software is 33.004 and make sure it comes with the Candi module is you're so inclined to get one. The Tech-2 is a must have tool to work on these trucks, more important than the wrench!

More heat from a manifold on one side than the other? My driveway faces east and down here the sun rises in the ESE so the tires are all over the place until they warm up. Then again, if I'm driving north on the highway in the morning the right side tires are higher then the left. These are LT tires which are more susceptible to temperature changes.

In Navarre, there's a Circle K/Exxon that shows they carry E85. Over in Oyster Bay is a Shell that carries it and another and a Pride on 181 between Clay City and Belforest. Probably not convenient.

The L83 goes from 355 to 382 horsepower on E85. Torque goes from 383 to 416 on E85. Besides free horsepower and a cleaner fuel system and motor, another benefit is variable and that is cost. Depending on where you live, the cost per mile may be significantly less. I'm running E30 and am within 1 mpg of what the motor gets on 93 but paying thirteen cents a mile to drive the truck instead of a quarter. Do the math. There's another benefit for those who live in the path of hurricanes. I'd resolved to never run E85 for the same reasons most folks think of. Then one night before a hurricane was due to arrive, I had to pick up and deliver some generators and this burned half a tank. Pulled into a filling station around 1 AM with lines at every pump but the one with the yellow handle. Pulled right up, topped off and went on my merry way while folks were still waiting in line. I'd almost forgot about that yellow gas cap!

The whole point of AFM is to increase fuel efficiency. I don't like it either but understand why, government regulations forced them into this option. That means, the knuckleheads we send to Washington eventually caused this. It's our fault for letting it happen. Now, back to your truck. Newdude's advice is spot on but I'll add something else that AFM looks for, vacuum. It looks to me from reading your posts that AFM is staying on too long, it's not switching off and re-engaging the four cylinders fast enough. This is a problem with the solenoids that stop oil flow to the injectors. If I were you, I'd take it to a different dealer and if that didn't get the problem resolved, I'd fix it myself. I would buy the MDI2 and GDS2 software to see what the computers are seeing and then fix whatever was wrong. There's nobody more vested in the health of your truck than the one paying for it, you!

A stuck lifter would cause a misfire that the engine's computer would detect. My AFM used to work at those slow speeds, why is that a problem? Get the truck tuned and have that turned off. Check your engine and transmission mounts.

My spreadsheet is at 22 tabs or pages now! The first is a cross reference as that is what I originally started these for back in 2006. The furthest right column shows if and when something was installed or changed. Other tabs include the gas mileage tests, fuel log, oil and tire rotations and their intervals, RPO Sheet decoded, VIN decoded, TPMS sensor positions and their age, drag racing stats, towing calculator, etc. It morphs from there and spills over into other spreadsheets that include transmission, driveshaft and tire calculators and the like. Then things like all the spark plugs, oil filters, tires, etc.

The best part of my BlackBear tune was what Justin did to the transmission, she runs fantastic, cold, hot doesn't matter.

After reading the first post, my first thought was that the Truetrac was a want and not needed. Any gear change has to offer increased fuel efficiency for that is the game. Same with tires. I do not remember, does Pepper have a 3.23 or 3.08 gear? Judging from the rest of the second post, I think she has the former. Those tires have served you well, beyond any of our expectations, going to run them again? Same size? What is the size?

I doubt that the Corsa exhaust will have anything to do with it unless there's a major defect in workmanship.

You need to see what the computer is seeing and do a data log to look for problems. Check fuel pressure at idle and under load, check the gap of your spark plugs. Check the injectors again and so on. These engines have enough sensors to quickly figure out what's ailing them if the right people are trained up in the way they should go.

A buddy has a V6 Silvy like Pepper with the double cab and I tell him about your fuel economy and he tells me his is nowhere near it. Of course, his is all stock and unless they're out of town with it, only driving a few miles each way to work and back everyday. Mine is hitting the average on E85 like the short wheelbase 2WD/4WD models, 12 mpg.

Your Maximum Trailer Weight is 9,400 pounds. Your GCWR is 15,000 pounds. To find out how much your rig weighed from the factory, subtract the maximum cargo capacity from the GVWR. Cargo capacity is found on the Tire and Load Information Label inside the door or door jamb (page 239). Just because it says 9,400 pounds doesn't mean you can pull 9,400 pounds. Read your owner's manual, I did! Start on Page 300.

Good points Brian. I've always liked to have a range of at least 500 miles. My current ride can do that on the highway as can the K2 pickups. If you figure them getting 22 mpg with 22 gallons of usable fuel that's 484 miles. Not so sure these new ones are as fuel efficient as their predecessors yet. I'm with ya, they should have more fuel at least as an option somehow.

That suggestion is what I did with mine and was able to get service records at the two dealerships that worked on it. Even have the mechanic's name. Wasn't able to reach the owner, he passed away. Google even showed the truck in his driveway.

Next time, hold 2200 rpms @ 70 mph in a lower gear and see what she averages mpg wise. It seems from reading these posts that even with DFM and the 400 pound weight loss that that huge front end is what reduced their economy compared with the previous generation.

So no V4 while coasting to a light or downhill off a bridge? If not, it's been turned off. Get a Carfax and see if it shows where the vehicle was previously serviced. Then call the dealerships and kindly ask them for any maintenance records. If you show proof of ownership they will usually give them to you. Somewhere along the way you'll identify the previous owner and can ask him/her directly. Might even be a member of this forum. If the truck has navigation, check for saved addresses and such.

Yes, the design and or the torque converter. This happened a lot with '15-'17 models as you can see through searching posts on this forum. I don't think the later 8-speeds were so problematic but it's worth looking into. I'm happy as a clam with my 6-speed and have no desire for more or a new truck!

Consider also that if he was running a 35" tire with a 3.73 rear gear, his final drive in 5th gear would be 4.74:1 All those extra gears gives them a lot of flexibility. More importantly though, I hope they got the bugs out of the 8-speed!

Don't know which model you're looking at so consider the numbers. First, the 8L90 8-speed transmission has the following gear ratios: 1st = 4.56 2nd = 2.97 3rd = 2.08 4th = 1.69 5th = 1.27 6th = 1.00 7th = .85 8th = .65 Most of these trucks have a 3.23 rear axle ratio so that gives them a 2.10 final drive ratio in 8th, 2.75 in 7th, 3.23 in 6th, 4.10 in 5th. With a 275-55-20 tire which mathematically is 31.91" in diameter, this would have the engine rpms at about 1550 in 8th at 70 mph or 3025 in 5th at 70 mph. A 35" tall tire would require 3.55 gears to run the same rpms as stock. A 37" tall tire would require 3.73 gears to run the same rpms as stock.

Know anyone with a good scan tool? It will be able to see the stored codes and why it's not working. A bi-directional tool can test the dash switch and the actuators on the axle and transfer case too to make sure they're working right.