Range Technology Plug & Play AFM/DFM Active Fuel Management Disabler

[19C7GS]

Constantly being in V8 mode would logically make sense that gas consumption would increase to some degree

Logically yes, however there are instances where V4 mode drinks more fuel than V8 mode from what I saw, it usually happens when the engine is lugging up a hill or something and it doesn't switch from V4 to V8, the computer is sending way more fuel to the cylinders in V4 to be able to have enough torque, while in V8 mode you don't need that much more fuel to do the same work.

It all balances out if the computer does it's job properly, which it does for the most part, but there are instances where it doesn't and it fails miserably. I caught mine spamming the switch between V4 and V8 like 5 times within a few seconds by playing with the pedal in a weird manner up a slight incline. Can't wait for the AFM to lock up and blow the engine lol

 

[cdnrx1]

Just to be clear, AFM, when activated and the engine is operating in V4 mode, deactivates the intake and exhaust valves and the fuel injectors on the designated cylinders. As such there is no fuel delivery to those cylinders so there is no situation where running in V4 mode would use more fuel that when the engine is operating in V8 mode.

WPGZ06's statement is correct and no amount of switching from V8 to V4 mode or "lugging" the engine would change the fuel delivery to the deactivated cylinders. If the ECU was to deliver more fuel during V4 operation, this would defeat the entire purpose of the AFM system.

This is a thorough explanation of the C7's AFM system.

Hope this helps.

Best regards
Ross

 

[WPGZ06]

Just to be clear, AFM, when activated and the engine is operating in V4 mode, deactivates the intake and exhaust valves and the fuel injectors on the designated cylinders. As such there is no fuel delivery to those cylinders so there is no situation where running in V4 mode would use more fuel that when the engine is operating in V8 mode.

WPGZ06's statement is correct and no amount of switching from V8 to V4 mode or "lugging" the engine would change the fuel delivery to the deactivated cylinders. If the ECU was to deliver more fuel during V4 operation, this would defeat the entire purpose of the AFM system.

This is a thorough explanation of the C7's AFM system.

Hope this helps.

Best regards
Ross

This was my understanding of how it worked. Any who are worried about fuel economy you really should not be getting AFM, or really a corvette for that matter lol

 

[19C7GS]

Just to be clear, AFM, when activated and the engine is operating in V4 mode, deactivates the intake and exhaust valves and the fuel injectors on the designated cylinders. As such there is no fuel delivery to those cylinders so there is no situation where running in V4 mode would use more fuel that when the engine is operating in V8 mode.

WPGZ06's statement is correct and no amount of switching from V8 to V4 mode or "lugging" the engine would change the fuel delivery to the deactivated cylinders. If the ECU was to deliver more fuel during V4 operation, this would defeat the entire purpose of the AFM system.

This is a thorough explanation of the C7's AFM system.

Hope this helps.

Best regards
Ross

Then there's a discrepancy of the fuel consumption gauge. I've seen it spike to 16L in V4 then switch to V8 immediately after and drop down by half.

 

[Canuck604]

Very good answers, so far no issues with my Range AFM disable

Regarding the lugging i think it gets really complicated and we would need an test, as yes lugging the engine in V4 uphill will technically only need fuel for 4 cylinders but also need more RPM from the 4 cylinders = more fuel, or is it better 8 cylinders operating at lower RPM going uphill, its very technical, i cant answer it.

But yes, my fuel consumption gauge shows less gas used after installing Range. As mentioned by other members , i should have done a real on paper gas mileage tracking before installing it but now i am afraid to remove it due to the lifter failures, but other fellow members say gas mileage got worse, so I believe it also depends on the terrain you live in.

If you live in flat land, most likely you enjoy more V4 benefits, I am in a very "hilly" city so not so much.
Very respectable answers from members, I think everyone is correct to some degree

 

[Rruuff Day]

This was my understanding of how it worked. Any who are worried about fuel economy you really should not be getting AFM, or really a corvette for that matter lol

I have a diesel Ford 250, a Lincoln MKX, a GMC Sierra and a 4 cyl Toyota Rav4. My Corvette gets better fuel mileage than any of them (although the Rav is close). From Red Deer to Vancouver and back, my average was 8.6 L/100km over the 2200 km. My best 100km average on that trip was 7.2 L. I tend to drive 15 to 20 over the posted limits with the occasional raped ape pedal when passing lines of RV's and truckers. Mine is an M7 and it's never been in ECO (AFM) mode and unless it's raining cats and dogs, it always stays in Sport mode with the engine management always dialed to Track exhaust..

 

[cdnrx1]

Then there's a discrepancy of the fuel consumption gauge. I've seen it spike to 16L in V4 then switch to V8 immediately after and drop down by half.

It's a momentary fluctuation as determined by the ECU software, throttle position, driving environment and numerous other factors that go into the makeup of the AFM command algorithms. This spit-second information, as seen on the DIC, cannot be relied upon to determine the relative efficiency of the AFM system and should only be used as a guide to help maintain awareness of your driving habits. It's basic information and is there for the driver to use, or not, at his / her discretion. It's a simple fact that driving in V4 mode provides better fuel economy than driving in V8 mode. Otherwise, GM would not be permitted to use the fuel saving data in their overall fuel economy claims as submitted to and approved by the EPA.

The relative benefits of AFM can only be measured using mid to long term fuel economy calculations and comparisons with information generated manually as well as that taken from the DIC. Most of the time the comparisons are similar. In my experience, and that of GM's fuel system engineers, AFM does, in fact, provide an improvement in terms of average, overall fuel economy.

I am not a fan of AFM for many reasons, in particular the poorly engineered lifter system and the failures related to the 8L90 8 speed automatic transmission, even though that's what's in my GS. However, if driven and maintained properly, the problems can be minimized and, in the case of the transmission, all but eliminated. I had a Range AFM disabler, used it for a year and sold it. Because I drive in manual mode 99% of the time I didn't need it. But if your using one you should still remove it and drive, occasionally, in full automatic mode. This is the only way you can effectively check for the "shudder" problem and, yes, it can still occur even if you have a Range device installed. The chances of it happening are significantly reduced but it can still happen.

Anyway, I hope that I've explained, to everyone's satisfaction, why AFM (V4 vs V8) actually does improve the C7's fuel economy under all driving conditions. Do I like the fact that it's there? Hell no, but I don't have a choice if I want to maintain the original powertrain warranty.

I'm done now.

Best regards
Ross

 

[WPGZ06]

I have a diesel Ford 250, a Lincoln MKX, a GMC Sierra and a 4 cyl Toyota Rav4. My Corvette gets better fuel mileage than any of them (although the Rav is close). From Red Deer to Vancouver and back, my average was 8.6 L/100km over the 2200 km. My best 100km average on that trip was 7.2 L. I tend to drive 15 to 20 over the posted limits with the occasional raped ape pedal when passing lines of RV's and truckers. Mine is an M7 and it's never been in ECO (AFM) mode and unless it's raining cats and dogs, it always stays in Sport mode with the engine management always dialed to Track exhaust..

Did not mean good mileage could not be had, but that most people are not purchasing a corvette with the thought process this is going to be good on a gas