Stay In 4mode Longer With Tune?

butzers09silverado · January 12, 2010

just wondering if anybody has, or knows if it's possible to tune the afm?

Mostly i think it kicks out of 8mode way to early with all the torque these things have...? maybe it prevents ping or something but i'd rather it require more pedal to kick out.

Stevens03 · January 12, 2010

A guy at diablo was writing custom tunes and was able to make a nice difference with the V4 mode coming on and staying on longer on the 5.3's. He' tried it with my 6.0 and I didn't see enough of a difference so I turned it back off.

brims · January 12, 2010

Any of the tuners can do it with HP Tuners or EFI Live. On the EFI Live forum someone had it set to stay in V4 mode to 10 or 15% throttle or something crazy like that.

AFM is a joke in a truck, I guess it's fine at 50 mph, but that's to slow.

butzers09silverado · January 12, 2010

Well if you don't tow often, then having afm is good when your commute is over 60 miles a day highway. thanks for the info good to know!

mhenshaw · January 12, 2010

When I had edge it stayed on for longer and would hold the speed better. Now that I have a blackbear tune, it does it even better. The truck holds its speed better in 4cl mode. It stays on a lot longer than stock.

So yes, tunes do help the 4cl mode. Don't expect 2 more mpg, but you can expect if you hold the gas pedal steady the truck will stay in 4cl mode for miles while slowly losing speed on inclines and gaining speed on descents. If you set cruise control it will still hold a little more than stock.

butzers09silverado · January 13, 2010

I wonder what a tune on a full exhaust replacement with ceramic coated headers x pipe dual high flow cats (maybe keep existing) and no mufflers plus maybe a 4:10.... the shorter gear would help decrease load and allow engine to stay in 4 mode longer, maybe even a shorter gear.

mhenshaw · January 13, 2010

I wonder what a tune on a full exhaust replacement with ceramic coated headers x pipe dual high flow cats (maybe keep existing) and no mufflers plus maybe a 4:10.... the shorter gear would help decrease load and allow engine to stay in 4 mode longer, maybe even a shorter gear.

If you have a 4:10 gear in your truck you should not even worry about AFM, because no matter what you are always going to get bad gas mileage.

And you couldn't stand to drive your truck with the exhaust, because it would be too loud in 4cl mode. Just adding a tune makes the 4cl mode louder.

brims · January 13, 2010

Sometimes V4 sucks after a tune it really depends. After the tune the truck would clunk in and out of V8/V4 mode, before the tune I didn't even notice it. Justin told me that some people have that clunking in stock form.

ybsane · January 13, 2010

I wonder what a tune on a full exhaust replacement with ceramic coated headers x pipe dual high flow cats (maybe keep existing) and no mufflers plus maybe a 4:10.... the shorter gear would help decrease load and allow engine to stay in 4 mode longer, maybe even a shorter gear.

If you have a 4:10 gear in your truck you should not even worry about AFM, because no matter what you are always going to get bad gas mileage.

And you couldn't stand to drive your truck with the exhaust, because it would be too loud in 4cl mode. Just adding a tune makes the 4cl mode louder.

I think he may be on to something here, our V-8's torque output is rated at a given rpm , what about when it goes into V-4 mode? does the torque output now require a higher rpm because of it running as a V-4.?

Most 4-cyl motors run a higher rpm at 1-1 ratio's and even in overdrive compared to a V-8, so why not something similar when the AFM mode kicks in?

I am not 100% sure on this but it is just driving my curiosity on the subject.

Rob

butzers09silverado · January 13, 2010

I think he may be on to something here, our V-8's torque output is rated at a given rpm , what about when it goes into V-4 mode? does the torque output now require a higher rpm because of it running as a V-4.?

Most 4-cyl motors run a higher rpm at 1-1 ratio's and even in overdrive compared to a V-8, so why not something similar when the AFM mode kicks in?

I am not 100% sure on this but it is just driving my curiosity on the subject.

Rob

It seems logical that you need shorter gears to optimize the tq, which is up in the 4g's on this thing... setup a "mode" for highway/no-load and another mode for loaded-city (just like tow/haul mode). above 62mph or above 45mph sustained for x duration it goes into Highway mode and runs in 4cyl 4th gear with no tcc lockup (or some other short gear combo, i.e. 3rd with tcc). If you hit a button it over rides highway mode and it turns off the afm.

Maybe i have this wrong, but if you're already turning 3g's, it's less work to spin the engine/tranny/etc versus being at 1800rpms, Centrifugal force and proximity to peak torque plus the much shorter final drive ratio in highway mode would require less work/load on engine and you're closer to peak tq.

there's a bunch of ways to solve that jerk issue if they brought the cylinders back 2 at a time instead of 4, would be my first guess or use the tranny more effeciently, esp. in 6spds.

about the noise, it sounds fine when i'm going down hill at 85mph in 4cyl mode, it'll still sound good in 8 mode when you're going slow you know what i mean?

jro909 · January 13, 2010

Well if you don't tow often, then having afm is good when your commute is over 60 miles a day highway. thanks for the info good to know!

the 4 banger mode is to save a little gas its not ment to be on all day and night, for a 60 mile commute you should of looked into that before you got a truck, part of the baggage of a fullsize is being bent over at the fuel pump..sorry to be blunt but its the truth, in this world is very hard to get ponies and good MPG in the same package, its one or the other

butzers09silverado · January 14, 2010

Well if you don't tow often, then having afm is good when your commute is over 60 miles a day highway. thanks for the info good to know!

the 4 banger mode is to save a little gas its not ment to be on all day and night, for a 60 mile commute you should of looked into that before you got a truck, part of the baggage of a fullsize is being bent over at the fuel pump..sorry to be blunt but its the truth, in this world is very hard to get ponies and good MPG in the same package, its one or the other

looking for some technical information, not opinions on whether my purchase was appropriate, thanks.

jdg2 · January 15, 2010

Turned my AFM off about 8 months ago after several attempts to get it to function smoothly. I have not noticed any change in average mileage. I think the more you try to get out of AFM the more noticeable it becomes. I personaly prefer a smooth operating drive train and all 8 cylinders running. I guess if you drive all highway all the time there may be a slight mileage benefit (maybe). This topic has been discussed many times before on this forum and most who have turned AFM off have left it off.

butzers09silverado · January 16, 2010

I've read quite a bit of that, but after some thought as mentioned above it seems logical why people are aggravated with it. the feel would naturally be harsh at low rpm heavy load versus high rpm light load, thus the concept of a 'mode' over ride in cooperation with tranny control.

i wonder if gm wastes time reading these forums, lol? maybe there is something to this idea? maybe not.

66nova · January 16, 2010

I think he may be on to something here, our V-8's torque output is rated at a given rpm , what about when it goes into V-4 mode? does the torque output now require a higher rpm because of it running as a V-4.?

Most 4-cyl motors run a higher rpm at 1-1 ratio's and even in overdrive compared to a V-8, so why not something similar when the AFM mode kicks in?

I am not 100% sure on this but it is just driving my curiosity on the subject.

Rob

It seems logical that you need shorter gears to optimize the tq, which is up in the 4g's on this thing... setup a "mode" for highway/no-load and another mode for loaded-city (just like tow/haul mode). above 62mph or above 45mph sustained for x duration it goes into Highway mode and runs in 4cyl 4th gear with no tcc lockup (or some other short gear combo, i.e. 3rd with tcc). If you hit a button it over rides highway mode and it turns off the afm.

Maybe i have this wrong, but if you're already turning 3g's, it's less work to spin the engine/tranny/etc versus being at 1800rpms, Centrifugal force and proximity to peak torque plus the much shorter final drive ratio in highway mode would require less work/load on engine and you're closer to peak tq.

The problem with this theory is peak TQ and Peak fuel efficiency do not overlap. While going to 4.10's MAY (key word, MAY) help your mileage if you drive in stop and go traffic a lot, they WILL hurt mileage on the highway.

there's a bunch of ways to solve that jerk issue if they brought the cylinders back 2 at a time instead of 4, would be my first guess or use the tranny more effeciently, esp. in 6spds.

There is never more then 1 cylinder firing at a time anyway. A lot of the "jerk" that people feel is actually the TC locking unlocking. A tuner does have the ability to control what %throttle the AFM is activated and deactivated.

about the noise, it sounds fine when i'm going down hill at 85mph in 4cyl mode, it'll still sound good in 8 mode when you're going slow you know what i mean?

I guess I don't know what you mean here? Most aftermarket exhausts have a very nasty drone when in 4 cylinder mode. They all vary, but the only exhaust that I have ever heard that is Corsa. Most of the rest sound like a "ricer" while in 4 cylinder mode.