Injector Dynamics
Dynamic Injector Flow Testing costs $35 per injector, and will answer all of these questions for you. It will also forever change the way you look at fuel injection tuning.
Download the Injector Dynamics spreadsheet and see for yourself.
There is a reason that all quality engine management systems require injector dead times/battery compensation values to be set, and the reason is simple. If the ECU does not know the dead time of your injectors, it cannot accurately command the injectors to deliver the correct amount of fuel.
One of the main benefits of electronic fuel injection is that it can account for atmospheric conditions, and deliver the proper amount of fuel to the engine under all operating conditions. But...it can only do this if it knows how long your injectors take to respond to a command pulsewidth. Without accurate dead time compensation, you may as well have a carburetor.
The problems that arise from incorrect dead times are numerous.
Inconsistent air fuel ratios. (The air fuel ratios are correct one day, and off by a mile the next.)
Under or over correction while tuning. (You ask for a 5% increase in fuel flow, but instead get only 3%, or maybe even 7%.)
Improper response to changing air inlet temperatures. (Your air fuel ratios change when the air temperature increases or decreases.)
Sluggish closed loop control. (The closed loop control is slow to react, and cannot make correcions before you get to the next point on the map.)
Closed loop control over compensates. (The closed loop control increases or decreases fuel flow more than it should.)
For instance, you tune your turbocharged engine perfectly on the dyno, but at some point atmospheric conditions change, and the ECU leans the mixture to maintain correct air fuel ratios.
If your injector dead times are correct, your air fuel ratios will be consistent. If your injector dead times are incorrect one of two things can happen, either the correction is not enough, and the engine runs rich, or the correction is too much and your engine runs lean! I'm sure you can figure out what happens next...
By now you're probably wondering "If injector dead time compensation is so important, why can't I send my injectors somewhere and have them tested?"
Now you can.
We recently completed our dynamic injector flow test bench in collaboration with the Motec USA engineering staff to help their customers and ours get the best results possible.
We are now offering dynamic flow testing to anyone who wants to get the most from their fuel injected engine project.
The service involves a 270 point dynamic flow test, and comes with an interpreter program which converts the raw flow data into information that is truly meaningful to the tuner.
The Injector Dynamics spreadsheet is fairly complex, and rather than try to explain it all here, we have a sample spreadsheet and instructions that can be downloaded by following the link at the top of the page. We strongly recommend that you read the Injector Dynamics text.
To simplify the ordering process, and to insure that we have the correct information for your application, please fill out the Injector Dynamics Order Form.
We will contact you as soon as we receive your information.
If after reading this, you still have questions, give us a call, or read a short article about injector dead time compensation.
Thanks for stopping by.
Paul Yaw
The Details
Dynamic flow testing costs $35 per injector for new pieces, and $50 per injector for used pieces that require the usual servicing. (Sonic clean, replace screens, pintle caps, and o-rings.) Your cleaned and tested injectors will be returned along with the Injector Dynamics spreadsheet which interprets the raw flow data.
Yaw Power Products