In this blog post, we’re covering the best 12v Cummins tuner available: AFC Live. Myer is going to walk you through set up, tuning, and getting the most from this incredible in-cab fuel tuner. Plus, we’re going to answer a lot of the most frequently asked questions we receive regarding AFC Live.

What is the AFC Live

AFC Live is Power Driven’s proprietary, American made, in-cab fuel tuner for p-pumped Cummins diesels. The design and setup of the AFC Live allows for near infinite adjustability right from the cab of your truck.

On your AFC Live, you have a Power Adjustment knob, the large, red knob. We often refer to this as the fuel quantity adjustment. Tightening the knob will give you more fuel. Loosening it will give you less fuel.

The smaller, black knob is the Fuel Rate knob. This adjusts how fast the fuel comes in. If you tighten it, it will take longer for the fuel to come into the engine and will feel “laggier”. If you loosen the Fuel Rate knob, you will have fuel coming in faster. This generally feels better and more responsive, but can also be smokey. The goal is to find the middle point where the fuel is coming in fast, but is also clean.

Next, we have the AFC pressure gauge. With AFC Live, we are modulating how much air your manifold is sending to the AFC and the pressure gauge gives you an idea of how much pressure you’re sending. This gauge is your tuned pressure. When switching to Max Power mode (see more below), this gauge will continue to show your tuned pressure, not max power pressure.

Finally, we have the Max Power switch. When the switch is up, you are able to make adjustments with the different knobs. When the switch is down, it overrides your knob adjustments and sends all the boost you are making to the AFC acting like a full power fuel tune. Turning on Max Power is great for when you want to switch from a tow focused tune to max fueling to race.

AFC Live Installation and Tuning

Myer recently changed up the compound turbos on his dad’s tow rig. Anytime you change the air on your truck, you’ve got to adjust your tuning.

First things first, we have to figure out how much pre-boost we have on the AFC. After you have installed your AFC Live, put the Max Power switch into the tuned mode (towards the gauge). Then, turn the fuel rate knob all the way down. This will shut off the air going to your AFC so that we know the fuel is from AFC adjustments. From here we can make some minor adjustments and begin tuning the AFC Live. To tune for RPM range, we will start from the bottom of our RPM band at a comfortable cruising speed, making no boost. Then, we are going to floor it and we should see quite a bit of smoke. In this rig, we are seeing about 20lbs of boost with just pre-boost fuel, which is a little excessive, so we are going to go into the AFC itself and adjust the fuel down slightly.

To adjust your pre-boost we’re going to adjust the pre boost screw to reduce fuel. In our example, we are going to need to loosen the stud about 1.5 turns. This will remove the extra fuel and clean up the smoke. On your vehicle, you may have to adjust more or less depending on the amount of fuel in your AFC. The beauty of the AFC Live is that this is the only mechanical tune we have to do. Once we have this dialed in, we make the rest of our adjustments in the cab.

Fine Tuning AFC Live In-Cab

Once we’ve got our preboost set, we can now make adjustments on the AFC Live. We start with the red Power knob (the fuel quantity knob) and first we back it out until there is no spring tension anymore to get a baseline of when you’re about to adjust that spring. Next, tighten up the Power knob three to four turns. You want to make sure the engine is asking for plenty of fuel because we will now tune our Fuel Rate knob. We want to transition to fuel as close as possible.

We will start by loosening the Fuel Rate knob by one turn. In this truck, that feels good, but we are also seeing a bit more smoke than we would like. To reduce that, we adjust the Power knob counter-clockwise slightly and repeat. You are now making fine adjustments to find the right combination of how quickly the fuel comes in with how much smoke your truck produces.

Adjusting AFC Live for Towing

To tune AFC Live for towing, we have hooked up an equipment trailer with one of our test rigs for extra weight. We are going to test this going up some hills to ensure we have the proper tune to manage coolant temps, EGTs, and will ultimately be sustainable without smoking out other vehicles on the road.

To start setting out towing tune, we back the Power knob all the way off. Then, we adjust it slightly to get about 10lbs of boost on the AFC Live gauge. This is probably too little power, but it’s our starting point. Then, going up a grade, you will floor your truck to see if you maintain or lose speed. As you start losing speed, adjust the Power knob, increasing power, to see at what level your speed starts picking up again. In this truck, we are seeing that we can maintain speed at about 30lbs of boost in the AFC Live. This also has very sustainable EGTs, coolant temps, etc. for this truck. We seem to be at a really solid tune for this truck.

AFC Live Frequently Asked Questions

What if adjusting the pre-boost screw on the AFC housing doesnt do anything?

If adjusting the pre-boost screw on your AFC housing doesnt seem to do anything, you likely need to make a coarse adjustment to the AFC housing itself before making the fine adjustments with the screw. Simply losen the four bolts holding the AFC housing in place and slide it back towards the firewall a bit. Then make your fine adjustments with the pre-boost screw.

What if making adjustments on AFC Live doesn’t do anything?

If you are making all the adjustments we have described here and nothing seems to impact your vehicle, the first thing to check is the plumbing of your AFC Live. The hose that is going to the side with the Max Power switch is connecting to the AFC housing. The hose connecting to the opposite side of the AFC Live should be connecting to your plenum or a boost source.

Next, check the quick exhaust valve and that the arrow is going towards the AFC housing. You can also remove the quick exhaust valve completely. Things will still work as intended, but you will not relieve the pressure from AFC as fast.

Finally, if you still find you are not getting results from your AFC Live you can simulate opening the Max Power switch. Disconnect the AFC Live from your head and your AFC. Then, take the section of line you cut off when you installed the AFC Live and connect things from your head directly to your AFC. This will simulate the Max Power setting in AFC Live. If you are still seeing an increase in power, it’s likely an engine or truck-side issue or an issue with your AFC.

If you suspect the issue is with your AFC, check that your AFC foot is installed correctly. Make sure the diaphragm is in the middle of its travel and not ripped or torn.

If everything is correct, but things are still not working, remove the AFC housing, take the foot out of it, and put the AFC housing back on. Without the foot, you should have 100% power all the time. If you are not seeing increases in power without the foot, you are now looking at a generic “why is my 12 valve not making power” issue.

We’re here to help with AFC LIVE

Our team is here to help you with any questions you have about AFC Live or any other diesel related questions. Give us a call at 435-962-9555 or text us at 435-962-9506 or leave us a comment below. Don’t forget to follow us on YouTube, Facebook, and Instagram for more product tests. Leave us a comment below about what you’d like us to cover next.