Electronically-controlled fuel injectors are very durable, precise metering systems capable of pulsing for millions of cycles. The most common problem with injectors is that they accumulate a buildup of wax, tar, and olefins inside the injector and on the pintle/seat area. These types of debris buildup will restrict the flow of fuel through the injector. These are elements of the gasoline that are baked on the injector after the engine is turned off and the temperature climbs to the highest point.

The injectors are manufactured to such close tolerances that a 5-micron buildup ( a human hair measures 40 to 90 microns) will reduce the flow up to 25%. The ASNU is the only cleaning method recognized to cleanse these precise metering devices without damaging the components. We have been using the ASNU system since 2004 and are a ASNU service center. Ultrasonic waves are used to break up the contaminates while the injector pulses. The debris is then carried out of the injector by a biodegradable chemical.

At Smith's, we are fuel injection experts, offering:

  • Cleaning Injectors
  • Replace All Applicable Parts (O Rings, Pintle Caps, Filter Baskets)
  • $25 per injector for Port Injectors (Minimum return shipping is $5)
  • Priced Each for the Whole Set
  • 4, 6, 8, 10 Injectors
  • Port Injectors

*Gasoline injectors only, low pressure (10 PSI) to high pressure (80 PSI)

Properly cleaned and maintained fuel injectors offer many benefits:

  • Savings to the motorist with improved fuel consumption
  • Lowered repair bills
  • Prolonged oxygen sensor life
  • Prolonged life of the Catalytic Converted Exhaust System
  • Preserves the environment from exhaust pollution by reducing CO (carbon monoxide) pollution by an average of 36%

How does the ASNU work?

ASNU spray chart
  1. FAIR - but weak
  2. BAD - split spray pattern
  3. BAD - split spray pattern
  4. BAD - jetting on left side
  5. GOOD
  6. BAD - feathering at top of spray

When the injectors are removed, the operator is looking for good spray patterns, flow rates, and any solenoid failure throughout the range. The injectors are removed from the vehicle and then ASNU tests for:

  • Leaks
  • Fuel Spray Management
  • Fuel Delivery Volumes
  • Electronic Operation

After the injectors are clean, the servicable items are replaced. The injectors are refitted with new filter baskets, pintle protection caps, spacers and O-Ring seals. Then the injectors are retested for leaks, spray pattern shape and atomization, fuel delivery volumes and correct electronic operation. When the operator is satified the the injectors are performing as a properly matched balanced set, they are ready to be returned to the engine. All results are recorded on the ASNU Service Report Pad.

ASNU System

ASNU System ASNU Logo

The injector's performance is critical to the correct running of the computerized fuel injected engine. With a dirty injector like this one, problems can range anywhere from lack of power to poor fuel economy, hard starting to rough idling, even to poor driveability.

BEFORE Dirty ASNU Injector
AFTER Clean ASNU Injector

ASNU's patented ultrasonic cleaning process and variable cycle program cleans the inside of the injector to their original manufactured condition.

Certified Mechanics in Bangor


We keep up with the latest technology. In fact, Smith’s Auto Tech was the first shop north of Boston with the ASNU (pronounced "AS NEW") Ultra Sonic Injection Cleaning System. We also use Computerized Diagnostics. When you take your vehicle to Smith’s Auto Tech, you are leaving it in the hands of ASE L1 Certified mechanics.

Vehicle Repair in Bangor


If we discover a problem with your vehicle, we will take the time to explain the problem and repair procedures. We'll help guide your decision process by answering any questions or concerns.

Reliable Mechanics in Bangor


Since 1927, Smith’s Garage has helped thousands of people maintain safer, more reliable vehicles. We look forward to earning your business and showing you how quick and easy it is to have Smith's Auto Tech maintain your car or truck.