Gas milage help!!!

[HUMTECH]

If you have no cats and your setting o2 sensor codes it will run in base fuel all the time, open loop operation. Thats whats killing your mileage.

[HUMTECH]

Larger tires will hurt mileage in stop and go traffic as it requires more throttle input to get going but will increase highway mileage as it has a taller gear ratio. Fix the "No converter problem" then see how it goes from there.

[Cesardajr]

Are you running a tuner/programmer to help recalibrate the gear ratio for the new tire size?
If not that will help, just make sure you find a tuner that can tune for the 40" tires.

[adamw89_2000]

Should I just get high flow cats or should I try and get some of those 02 sensor simulator things?? Ian not running a tuner at the moment.. U think that will help? Who makes one capable programming for a tire that big? I've though about gettin s custom time done rather than a hand held but not sure which would b better overall now.

[HUMTECH]

Simulators work good, have them on my 98 truck. If they are available for the 6l def would. If they are not available you need some cats. Ive never sourced them for a 6l so i honestly cant make that call. Google is your friend...

[tyler1bo]

Wouldn't a regear help? Like 4.88's?

[DeLH2]

I'm getting 13 on the highway and 10 in the city with lift and 37" tires. Wonder why yours is so low?

[[__--MUD--__]]

Originally Posted by tyler1bo

Wouldn't a regear help? Like 4.88's?

4.88 will be less gear than stock ratio setup, 5.13 would be a little more. It would make a major improvement. I'm sure it feels like a lazy pig right now.

Honestly this rig in question is going to need $6000-10000 in additional parts to get it to drive as stock or better. Gears are $1000, Install for gears runs anywhere from $800-2000. Although not mentioned, there is no way that truck brakes now like it should now. Big Brake kits on all 4 corners start at $5000 if you get lucky. No way any of the stock steering is going to hold up for any decent amount of time. At a minumum, $1500 in steering components. To do everything your around $3500.

I really think that anyone that sells/installs lift kits should thourghly go through w/ the buyer all the additional work that will need to be done after the kits are installed. The lift kit ends up being the cheap part when you have to upgrade all these other components.

Im in the middle of putting 5.13's in my rig and im currently running 37" tires.

[glennf1]

Originally Posted by HUMTECH

If you have no cats and your setting o2 sensor codes it will run in base fuel all the time, open loop operation. Thats whats killing your mileage.

The o2's upstream *before* the cats effect fuel trim. The o2's *after* the cats have no effect on fuel trim and are only there to make sure the cats are working for emmissions.

[HUMTECH]

Your absolutley right, pre cat o2 sensors monitor and adjust fuel trim but when the post cat sensors are not in the picture it puts the system into open loop operation and runs in a base fuel model which is always rich mixture.

[adamw89_2000]

Ive got a buddy that installe numerous gears in older card and specifically 9" fords. He's very good installer and he thinks he does not want to tackle the gears in the h2... He days he's not Forster but in some later model gm trucks you have to use a case splitter... It essentially stretched the whole bigger to get the guys out..... Anyone know if this is required on the h2s? If not we can install my gears and save me a ton of $$ . I called a well know shop and try want 2g for 4.88 installed and give me no warranty! Which I think is bs.... As far as brakes go... It's not bad, not the best but not bad.... I pull a 16ft landscaping trailer 75% of the time too... You just gotta b a smart driver.... As far as steering componets.... My front end shop assures me these front ends r not junk and can handle these wheels and setup I have.... I don't offload this truck so it's not abused by anymeans.... They suggest I keep everything lubes often and I will b fine.... They suggest I keep my stock front end until I get some wear in them before I go upgrading things.... Kits been on for 12,000 mi now and no wear yet... Only had to retighten the lift kit bolts...

[adamw89_2000]

And on the sims for the cats, any clue where these guys are buying them from? They r getting hard to find.

[Humdingah]

Originally Posted by adamw89_2000

He days he's not Forster but in some later model gm trucks you have to use a case splitter... It essentially stretched the whole bigger to get the guys out..... Anyone know if this is required on the h2s?

You should try calling Randy's Ring & Pinion's tech line...they can tell you what's needed with a gear change in the 9.5 AAM and can also give you pricing on the gears front and rear and all of the other necessary items (shims, crush sleeves, etc).