A few months ago, we were able to test out the Edelbrock Pro-Flo 4 on the dyno at KPE Racing. Since then, we’ve installed the engine in our test subject and were able to put some miles on our Suburban to get a feel for Edelbrock’s fuel injection system in the real world.
The engine that we used in the Suburban was a typical 5.3 junkyard LS purchased out of a 2004 Chevrolet Avalanche. Like most LS swaps, this engine has 100,000 miles on it. We decided to do a COMP Cams cam swap and upgrade the rockers with COMP’s shaft mount units since the factory parts tend to breakdown after a while. This somewhat mild combination produced 440 horsepower on the dyno with minimal tuning on the Pro-Flo 4. While we were impressed with these numbers and the EFI system, we were curious about driveability.
In the past, we have come across some “self-tuning” EFI systems that were fine on the dyno, but when it came time to put it to use on the streets, problems emerged. Drivability, gas mileage, and reliability all suffered. One particular unit would backfire and die at will. We would have been much better off leaving the carburetor the vehicle. After calling customer service several times, the system was finally removed and thrown on a shelf left to rot. We were hoping to steer away from these unwanted problems with the new system from Edelbrock.
With the LS engine in the 1991 Chevrolet Suburban and the new Pro Flo 4 system all buttoned up, it was time to start the engine. However, we knew that there was a new firmware update that needed to be downloaded to the Pro Flo 4. This process proved to be easy enough and we were ready to go in a matter of minutes. Much to our liking, the new firmware will now support boosted applications. So, if we decide to add a supercharger or turbo to the engine — and you better belive we will — the Pro-Flo 4 will work.
Since we forgot to save the engine settings that we used on the dyno, we connected to the ECU via Bluetooth with our tablet and ran the setup wizard. When the wizard had worked its magic, we hit the ignition, and just like on the dyno, the engine roared to life. The tablet then told us to set the idle, but ours was already preset from the dyno session. After the ECU sees 165-degrees of engine temperature, it unlocks the advanced tunning capabilities. We knew from the dyno that we needed to bump the redline up to 7,000 RPM and add two degrees of timing. These settings will make our little LS happy from the beginning.
After the engine was up to operating temperature, we checked all of the fluid levels and looked for any leaks that we might have missed. Almost immediately after the LS was up to temperature, one of the GC Cooling electric fans kicked on. Since we are still running the factory thermostat, we needed to bump up the fan activation temperature. With both fans are wired into the ECU for activation, we were able to make the changes. As we bumped up the temperature setting fan one turned off. Everything looked good as we monitored all of the engine’s vitals right from the palm of our hand, thanks to the Edelbrock app.
Since the tablet is such a vital part of the Pro-Flo 4 system, we decided to mount it up on the dash. This location would allow us to monitor fuel pressure, water temperature, air/fuel ratios, throttle position, RPM, among other parameters at a glance. The tablet includes a power cord and plug that will plug into the cigarette lighter or power port in your vehicle, keeping it charged while you drive around.
It was a moment of truth as we threw the old ‘Burb in reverse and backed out of the driveway. We idled down the drive and came to a stop before hitting the main road. A glance at the tablet reassured us that our maiden voyage would be a success, so we headed out.
The engine pushed the Suburban up to 30mph on the side road with no problem. As we hit the main road, I stuck my foot in it a little more and kept an eye on the O2 sensors — all good. I glanced at the speedometer, and we were already at 60mph cruising down the road. So far, the Pro-Flo 4 had performed was flawless. It felt and reacted much better than the TBI system that Chevrolet designed for this vehicle. Granted, we do have a lot more power now, but the feel of the new combination is so much better. But, our first stop sign was coming up, and I was hoping the Pro-Flo 4 wasn’t going to let us down. As I let off the gas, the engine mellowed out to our idle speed of 850rpm. We came to a complete stop. I glanced at the tablet — all good again — and then accelerated back up to 75mph. The engine didn’t stumble, and nothing popped or backfired. Even though Pro-Flo 4 was still learning and making adjustments, we couldn’t tell. We were now rolling down the highway at 80mph on our way to town.
We hit the edge of town and did the usual routine by stopping at a gas station. Again we were a little apprehensive of the EFI system as we shut the engine off to fill up with gas. Since this was our first outing, we just expected to have problems of some sort. And since this trip was highly uneventful so far, we just knew it wasn’t going to start. With the Suburban loaded up with all of the fuel it could handle, we hopped back in the truck and hit the ignition switch. Like a new vehicle, the old square body fired right up, and once again, we were off.
Over the years, I have figured out that there’s no one better to test a product than a teenager. With that thought, I turned the Suburban keys over to my son Chase. This 19-year old has a way of finding weak links and exposing them in an extraordinary fashion.
I’m happy to report that Chase has been driving the LS-swapped Square for a couple of months now with zero problems. It starts on cold days the same as it does on hot days with no hesitation. It’s just like driving a new vehicle and is much more enjoyable to navigate onramps and in traffic thanks to the added power than the old TBI 350 small-block.
The Pro-Flo 4 is easy to install, and tuning it could not be any more simple. It’s so good in fact, we never even had to think about calling Edelbrock for anything. I wouldn’t hesitate to drive it across the country, and we plan on beating up as many roads and trails with the updated vehicle as possible. Who knows, we might even take it to LS Fest this year.