Preparing Perfect Tuning Results With Proper Injectors, Part 1

The internal combustion engine requires four primary things to run properly: air, fuel, spark, and compression. When you lack one or more of these four, you induce either a poorly running engine or a non-running engine altogether. In a high-performance application, these primary items become very specialized. In the case of fuel injectors, a poorly manufactured or incorrectly sized fuel injector can not only rob an engine of horsepower and cause damage, it can also create a tuning nightmare in the process.

Injector Basics

To understand this scenario better, we first need to look at what the differences are between a cheap eBay injector and a properly manufactured one. While we can all infer an injector is simply the unit that injects fuel into the engine, to a tuner it is much more than that. The injector is the lifeline to ensuring that the engine is going to remain healthy, run optimally, and not have any catastrophic failures that can be pinpointed back to them.

So how does a tuner make a decision on what injectors to suggest? Well, this is based on the factual data that is provided with quality fuel injectors and their preference after years of experience. Quality fuel injectors will include injector tuning data, a pulsed-flow sheet, and come in flow-matched sets. While cheaper injectors will give you a claimed cubic centimeters per minute (cc/min) or pounds per hour (lb/hr) rating, measuring open flow, they don’t usually  provide any injector tuning data, or a pulsed-flow number that could determine variances between each injector. This leaves a gray area that most tuners will want to avoid, as they’ll be spending an exorbitant amount of time trying to create a clean primary fuel table with unknown data. In other words, before ordering injectors, talk with your tuner first and don’t cheap out.

You said you were 120 lb/hr, the injector flow bench determined that was a lie.

Data Dilemma

Unfortunately for your author, the previous owner of my vehicle had not followed any professional tuner’s advice nor did he bother to research injectors at all. While money was not the cause of his decision, it was clearly a lack of knowledge that led him to a set of 120 lb/hr injectors. Judging by the other faults I’ve found in this vehicle, it’s safe to say he grabbed these based on physical size and claimed flow rate. It’s obvious that he never had  the injectors on a flow bench to verify.

This nightmare quickly became a reality for my tuner and myself. Every time we would create a log we would have to increase the VE table numbers to offset a lean condition. This should have created an enrichment that would be visible through our wideband gauges and recorded lambda readings However, everything would still show a lean condition. We quickly began to point fingers at the wideband sensors or an injector issue. Seeing as how the wideband sensors are on different banks and controlled by separate systems, it became apparent my injectors were probably injecting more problems than fuel.

Rolling With The Flow

While my garage mechanic senses were tingling, my penny-pinching ways were telling me to first verify that my injectors were at fault before funding a new injector adventure. Thankfully, there are still shops that specialize in fuel injection and have the ability to test open and pulsed flow, as well as clean injectors. One such highly recommended shop is Fuel Injection Specialities in San Antonio, Texas, owned by Tracy Meinert.

Meinert does more than just run an injector flow bench and a business. She is a tuner and understands the importance of injector data during tuning. So when she told me the important things she looks for in injectors, I listened. Her list included flow rate, short pulse width, and injector offset as critical data to have before she takes on a job.

We expected to see the most variance during the pulsed-flow testing, however, the open-flow test was not much better. During the first round of open-flow testing, one injector dribbled only trace amounts of the heptane used to test flow. Heptane is used to simulate fuel on an injector flow bench, as it is consistent in weight without the flammability aspect of gasoline. However, heptane does provide an added cleaning effect, so we decided to run a second round on this injector to see if maybe the pintle had clogged. This time around it filled the beaker to around 40ml in a 4-second span.


While the heptane had already been drained from a few cylinders, the variance between each filled cylinder caused great disappointment in the previous injectors.

My idea of saving money and replacing only one injector was dashed shortly after. Even with the pitiful-performing outlier removed, injector-to-injector variance still exceeded the 20-percent mark. Since time is money, it would be cheaper to replace the injectors than face the headache of tuning around these injectors. Meinert left me with one last bit of knowledge before I loaded up my bad batch and headed out: “If you can trust the data, you can trust that it will aid the tuning process.”

The DeatschWerks Difference

Once the injectors were determined to be the point of fault, and the bane of my tuner’s existence, I sought out a company that provided quality injectors that met the required parameters, and were  tested before shipping, as Meinert had suggested. This led me to the team at DeatschWerks. I proceeded to interrogate the technical staff on their testing processes to avoid the same disaster as before. 

I was connected with expert on-staff tuner Dakota Bowman to discuss the steps that DeatschWerks takes before shipping any injector out. 

“All testing is done through a modified flow bench that reads in real time,” Bowman explains. “This shows exactly what the injectors are flowing down to the CC at any given moment. While a typical injector flow bench can be used to see if an injector is working, it can’t determine volume as accurately as our machine.”

“For testing we run multiple tests, including static for a well-rounded flow rate number and dynamic to represent more of what the injector would see in a running engine,” says Bowman. “Pushing past that, we perform four other tests that include variables like high-load and high-RPM down to light-load and light-RPM in 7, 5, 2.2, and 1.8 milliseconds intervals. If we are testing any injector above 1,000cc, we take an extra step and use a slightly lower pulse width testing to make sure it still retains good idling functions. The injectors are then matched and balanced when they meet five requirements.”

While a conventional flow bench is great for testing and cleaning, it's far from adequate from a manufacture's position. This becomes especially true when trying to batch 200 injectors with similar flow rates. Instead of reading a beaker, DeatschWerks uses a modified flow bench that reads in real time. This process shows exactly what the injectors are flowing down to the CC at any given moment.

DeatschWerks individually labels each injector, and through the use of its proprietary software and multiple points of data, can place each injectors into similar sets. “Our target at high load is in the 2-percent range,” Bowman says. “While the flow report in the injector box is a part of this testing, it is not the tuning data. Our tuning data can be located on our website.

Properly Sized Eight Pack

After Bowman and I spoke, I was sold on DeatschWerks injectors. Their testing, batching, and ability to provide very low variance between the set would be overwhelmingly better than my previous set. I tend to oversize my purchases, so I decided to use DeatschWerks online injector calculator. Entering the horsepower desired, fuel used, and forced induction applied concluded that DW’s 1,500cc/min injectors (143 lb) would suit my desire to max out a Vortech YSi supercharger on a 418 cubic-inch engine while producing a streetable idle. idle. Since my truck runs on E85 and I’m looking for future growth, it made sense to up-size the injectors to compensate for my long term goals.



Since DeatschWerks keeps these injectors in stock and I’m just south of its Oklahoma facility, I was able to receive my new eight-pack the following day. As I carefully read over the flow report, the injectors showed an overall variance of only 0.6-percent. This is a huge improvement over the 20-plus-percent variance the last set had. Now that we have finished step one of selecting an injector, the next step will be installing these precision crafted injectors into the engine bay and begin logging data and tuning. So stick around as we prepare to check the word of DeatschWerks against the tuning process!

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About the author

James Elkins

Born into a household of motorsport lovers, James learned that wrenching takes priority over broken skin and damaged nerves. Passions include fixing previous owners’ mistakes, writing, and driving.
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