Quick Case Study: Direct Injection Flow Balance Considerations
The below vehicle was experiencing misfires even with known-good calibration work. Despite being so new, we suggested and injector flow test to identify what might be going on. The results speak for themselves.
If you follow our injector cleaning schedule, you might be considering simply replacing your DI injectors with a new set of DI injectors. That works fine, but it doesn’t tell you how your last set of injectors were doing. You need to know this so you can adjust your injector cleaning interval per your fuel quality and specific usage. Anytime you replace your injectors, make sure to have the old set cleaned. Mark each injector when removed so you know which is which, as well.
So imagine in this case, cylinder 1 is operating at 72% capacity and then the port injector that gets put into that cylinder only flows 90% of what the other 5 port injectors do (*or all 6 flow various offsets of each other even +/- 10%) and then you factor in running them for a duration of time with full e85 (not cycling pump fuels or running fuel filtration) so the port injector could be running at 80% capacity...so you could be in a situation where cylinder 1 fueling is only capable of flowing 60% and who knows what the balance of each of the other cylinder is and then your bank fuel trims are reading the indifference from 3 cylinders at a time...cylinder 1 could be lean, cylinder 2 could be rich and cylinder 3 might be fine.
The below imagine is what this looks like to us; this is the DME trying to save the engine from irreparable damage. This is the same strategy some calibrators disable, or tell you not to worry about. They’re right, it doesn’t look good in the log, however, it is telling us something.
The point being we try and recommend good injectors to start because things can go badly really quick when the injectors get some service life on them without cleaning or proper fuel filtration. We only work with the best injectors and those are from Injector Dynamics
Let’s talk about PI injectors for a moment.
Why do we recommend ID injectors for your PI system?
Known quantity
Known injection flow values
Low pulse width delivery and linearity that is not equaled by other injectors on the market
Reasonable price given the cost of any engine/turbo system
Without going too deep into it, let’s start with the end of the story. The end of the story is that the best calibrators and race shops in the world suggest and use ID injectors and products. That should be a good selling point from a logic perspective. For the skeptics; you actually have more margin to be made on lower cost injectors than the best parts, which makes the motorsport industry its own special situation. So if your shop is suggesting these; know that they are likely skipping the “flow bench matched Bosch set” they can buy for $250 and double the price, and suggesting you spend a little more while they make a little less money. The upside? Their life, your life, and the vehicle’s life is better.
The less expensive injectors do work, and are generally fine at WOT. Where the better injectors earn their keep is in the low load, injector minimum, and balance. That won’t show up on the dyno sheet, but it will show up almost everywhere else in operation.