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Afm V4 Mode Toggle Switch


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#1 camaroguy94

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Posted 16 June 2009 - 10:47 AM

So I was just thinking has anyone ever though installing a toggle switch to keep the truck in V4 Mode. I dont need all that power all the time. I know it this probally will cause a ton of issues but just thinking out loud.

How much better MPG could I get???

#2 swhitney2003

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Posted 16 June 2009 - 10:51 AM

So I was just thinking has anyone ever though installing a toggle switch to keep the truck in V4 Mode. I dont need all that power all the time. I know it this probally will cause a ton of issues but just thinking out loud.

How much better MPG could I get???

AFM is programmed into the ECM. There is no way to have a toggle switch for it. If you were to run V4 all the time, it would probably get worse gas mileage as you are trying to move a heavy vehicle on half the power. At times it is more efficient to use 8 than make the 4 cylinders struggle to provide enough power.
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#3 cerbomark

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Posted 16 June 2009 - 10:54 AM

I don t believe that engine is made to run that way and I bet you d do major damage. That s why it s programed with limits of how long it will run in that mode.
Anf IF you could or did you d get great gas mileage while your taking a bus :rolleyes:

Edited by cerbomark, 16 June 2009 - 10:56 AM.

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#4 brims

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Posted 16 June 2009 - 11:25 AM

I toggled mine to full time V8. Technically Justin did, but minor details. I've seen no difference in gas mileage since doing that. Trucks shouldn't have 4 bangers, part time or otherwise.

Edited by brims, 16 June 2009 - 11:26 AM.

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#5 Sir Dan

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Posted 16 June 2009 - 12:17 PM

I toggled mine to full time V8. Technically Justin did, but minor details. I've seen no difference in gas mileage since doing that. Trucks shouldn't have 4 bangers, part time or otherwise.

+1 !!!
Very minimal increase in mileage and just in city if any at all. It's a great technology for cars, but NOT trucks. :rolleyes:
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#6 VMax2007

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Posted 16 June 2009 - 12:19 PM

I toggled mine to full time V8. Technically Justin did, but minor details. I've seen no difference in gas mileage since doing that. Trucks shouldn't have 4 bangers, part time or otherwise.

+1 !!!
Very minimal increase in mileage and just in city if any at all. It's a great technology for cars, but NOT trucks. :confused:


What they said! :rolleyes:

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#7 07SLT

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Posted 16 June 2009 - 12:33 PM

So I'll retain the 19-20 mpg (highway) that I get now after turing my afm off? Sorry, I'm sceptical.

#8 VMax2007

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Posted 16 June 2009 - 12:42 PM

So I'll retain the 19-20 mpg (highway) that I get now after turing my afm off? Sorry, I'm sceptical.


Obviously everybody's results will vary.

But my truck NEVER went into V4 mode above 65 MPH. I drive mostly city/inter-city freeway. And when I do get on the freeway, I never drive less than 65 MPH. It also never stayed in V4 mode unless the freeway was flat/downhill and my speed was 60 MPH or less. One time, as a test, I set the cruise at 55 MPH and waited for a flat section of freeway. The AFM came on, I turned on the AC and it went to V8 mode. :rolleyes: And this was before my leveling kit and wheels/tires.

Yes, if drive slow enough on flat hwys, I suppose AFM might net you 1-2 MPG increase.

In my case, I have seen ZERO dropoff in my MPG since shutting it off.

I still say a 8/6 AFM system would have made much more sense in these huge trucks.

Edited by VMax2007, 16 June 2009 - 12:44 PM.

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#9 Silverado4x4

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Posted 16 June 2009 - 12:42 PM

So I was just thinking has anyone ever though installing a toggle switch to keep the truck in V4 Mode. I dont need all that power all the time. I know it this probally will cause a ton of issues but just thinking out loud.

How much better MPG could I get???

The system is designed to run in 4 mode for a max of I think 7 minutes if nothing is there to kick it out, the reason is for keeping the even heat transfer inbetween cylinders.

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#10 Nick The Great

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Posted 16 June 2009 - 12:53 PM

I wouldn't see why a toggle switch couldn't be added. It'd probably take some relays, signal conditioners, logic gates, and a good understanding of EFI live or whatever. I seem to recall Justin was adjusting stuff on the fly during my tune. Not AFM, but shift points and such.

Maybe it's not a good idea, but it sounds like a fun project to me. :rolleyes: I think it'd be fun to have a bunch of little dials to adjust your shift points, and other parameters. :confused:
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#11 VMax2007

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Posted 16 June 2009 - 12:56 PM

I wouldn't see why a toggle switch couldn't be added. It'd probably take some relays, signal conditioners, logic gates, and a good understanding of EFI live or whatever. I seem to recall Justin was adjusting stuff on the fly during my tune. Not AFM, but shift points and such.

Maybe it's not a good idea, but it sounds like a fun project to me. :rolleyes: I think it'd be fun to have a bunch of little dials to adjust your shift points, and other parameters. :M16:


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#12 iminaquagmire

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Posted 16 June 2009 - 12:58 PM

Its also designed to switch back to 8 cylinders if the the throttle exceeds 6% IIRC. If you equate that to HP, that's 18.5 HP. Anytime your truck needs more power than a lawn tractor, it switches pack to 8 cylinders..
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#13 DofD

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Posted 16 June 2009 - 01:07 PM

When I get around to getting a tune done (there are other priorities), I'll get AFM turned off. The terrain around here is just too hilly (city or highway) for AFM to be of any benefit. AFM only comes on for a few seconds if I'm on flat ground going a constant speed or going downhill. Maybe in an hour of driving I might get 1 minute in V4 mode.
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#14 gmowner4life

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Posted 16 June 2009 - 01:15 PM

You would probably get worse gas mileage because of the amount of power you would need to get momentum. The weight to power ratio would not let you have any gains in mileage. :rolleyes:

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#15 VMax2007

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Posted 16 June 2009 - 01:32 PM

Conclusion:

AFM SUCKS (in it's current form in trucks anyway).

/thread

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