“The problem with that is you are adding more small pieces [to the valvetrain] that are cycling at several thousand RPM,” White explains. “Plus when you aren’t firing that cylinder and there is no heat going into that combustion chamber, then you run into other problems with ring seal that leads to oil consumption and carbon build-up on the cylinder wall. Over time, you have problems with oil consumption and valve train failure. It’s pretty common to hear someone say they have a Tahoe that’s only a few years old with 85,000 miles on it, and they have to put two quarts of oil in it every 3,500 miles. If one of those lifters collapses and stays collapsed, you can even wipe the cam out.”
With the added expense and potential warranty issues posed by these cylinder deactivation systems, there has to be a compelling up-side for manufacturers in terms of fuel economy improvement, and there is - but with a major caveat. In order to provide consistent results, government fuel economy testing is performed under a set of rigidly-defined circumstances. Though this ensures buyers can make apples-to-apples comparisons between vehicles, it also means that the OEMs are incentivized to come up with ways to maximize fuel economy under those specific test conditions.
This cutaway of a Gen 3 hemi shows oil gallery (yellow) that controls the MDS operation. Note the solenoid at the front of the engine and the specialized MDS lifter.
It’s not fair to call it cheating, any more than it’s cheating to take an SAT prep course to get a better score on that standardized test. But as they say in the ads, ‘your mileage may vary.’ “Unfortunately, the EPA tests don’t correlate with real-world driving, so you don’t see the same benefit,” White adds. “It lets them claim the vehicles get better mileage and helps meet emissions standards.” Depending on your driving style, you may not experience any benefit, but you’ll definitely notice the system in operation.
Range Technology AFM/MDS disablers simply plug into the OBII port under the dash and effortlessly disable both of those systems.
Switching from light-load four or six cylinder operation back to running normally on all cylinders isn’t an instantaneous process even with the most modern vehicles that employ cylinder deactivation; “In terms of drivability, there’s a delay reactivating those cylinders so you have issues with throttle response,” White explains.
Another fuel saving strategy being employed on more and more vehicles is ‘start/stop’ technology. Rather than idling when stationary at a stoplight, when the vehicle is motionless for more than a few seconds and other key parameters are met, the ECU is programmed to stop the engine, then restart it when the driver releases the brake and presses on the accelerator.
“Auto start/stop is done for the same reasons [as cylinder deactivation], but people will see more of the benefits from it,” White opines. “There have been concerns about it putting a lot more wear and tear on the starter, but that’s really not a big deal for the way they’ve designed the systems. What it really is more than anything else is an annoyance.” In very hot climates, though the vehicle’s ventilation system will continue to circulate air, without the refrigerant compressor being turned by the engine the air conditioning can get ‘behind the curve’ and have to run longer once the engine starts to catch up, and in cold weather no heat is being produced for cabin climate control, not to mention the extra demands placed on the battery when its capacity is at its lowest. Of course, there’s also the momentary hesitation when it’s time to get moving once again, and that’s the main reason many people dislike the start/stop feature.
Fortunately, there’s a simple, inexpensive, and easy way to restore full function to your late-model GM V8, Chrysler Hemi, or Ford vehicle with Range Technology’s plug and play devices. Their AFM/DSM Disabler for GM, MDS Manager for Hemi, and Start/Stop Disabler modules for both GM and Ford applications allow owners to quickly and reversibly gain complete control over these features via a small electronic module that plugs in under the dash to the vehicle’s factory OBDII connector.
Per White, “The parts are just about universal - we just have two part numbers for GM. One is for start/stop and the other is for AFM.” Another covers Hemi cylinder deactivation, and a fourth is designed to eliminate the start/stop function in a wide range of Ford applications. “It’s just a plug that goes into your OBDII port, and all it does is interrupt the signal from the PCM to the engine to activate that system,” White continues. “The vehicle never knows that it was ever engaged. You basically just plug it in, and the LED will light up to show it’s receiving power. You plug it in, turn your car or truck on, and forget about it.”
While there are other methods to achieve the same results, they often involve reprogramming the factory computer, which can lead to issues should you ever need to take your vehicle in to the dealer for service. Not the Range Technology devices, though: White says, “It won’t affect your warranty; if you take your vehicle in for service, just unplug it, and when they’re done, plug it back in. If you ever want to return your vehicle to stock, you just unplug it. There’s no trace, and it doesn’t interact with the computer - it’s just interrupting that signal. And it will work in any of the vehicles it covers, so you can move it from one to another.”
It’s literally so simple that if you can plug in a USB cable the right way once in every three tries, you’ll have no issues whatsoever with installation. “People think that they’re going to have to follow a lot of instructions or disconnect things under the hood, but it’s literally a five-second process. They think there has to be more to it,” White says with a chuckle.
“A lot of owners don’t even know what this technology is, and they think they just have to live with drivability or reliability issues,” laments White. “Once they understand how simple and inexpensive it is to fix, that’s all it takes to convince them. If they go to the dealer and say it’s acting funny, they aren’t going to find anything wrong because it’s doing what it is intended to do. But down the road a few years, they do a Google search on ‘why is my Suburban burning oil like crazy?’ and then they start to suspect this is what caused it.”