The two throttle-body fuel injectors that came with this 550-200 Avenger EFI system are failing, and produce ropy/streamy/poor-quality fuel spray patterns, as well as active singular drips of fuel at idle mixed with the spray pattern. The idle RPM coughs every time there is a fuel drip from either injector, and the WBO2 sensor registers the richness and the EFI tries to compensate. It results in the car stalling once in a while. Fuel economy has been degrading over the past few months, as well.

I'm a senior aerospace fuel system engineer, and former professional mechanic. I performed the EFI installation meticulously. The new fuel tank, new lines, proper upstream filtration (from the pump) and downstream filtration on my car preclude contaminant-based failure of the injectors. Troubleshooting involved new o-rings for the injectors, inspection of the built-in screens, pressure testing for leaks, inspection and video photography of the spray pattern.

Conclusion: The fuel injectors are worn out. For having 18,000 miles on the car with the EFI installed, this correlates to a mean time between failure of approximately 650 operational hours. This is an unacceptable level of wear. Furthermore, the steel hold-down bracket that pushes on the top of the injectors to hold them in place is an overly flimsy design, and was problematic for securing the injectors back in place during servicing. The metal is simply too thin to provide the necessary strength.

New injectors were ordered from Holley and installed last week. The new injectors demonstrate a quality, mist-like spray pattern, consistent with proper fuel injector performance. I fabricated a thicker version of the injector hold-down bracket to stop the fuel leaking from the upper o-rings.

I request some level of acknowledgement of, and compensation for, the design. Surely the various automotive enthusiast internet forums would be interested in learning of these types of quality issues. Holley is a brand name I've trusted for three decades, and I'm let down. I have spend many thousands and thousands of dollars on your products.

I tried sending this to the online technical support request (, but the form fails to submit.