Injector Test and Service (ASNU)

The Electronic Injection System

The Injector Valve has the finest tolerances of any mechanical component on the engine.

How do we check these tolerances?

We are constantly checking Milliseconds, Millivolts, Milliamps.

When do we check Millilitres of fuel?

Un-burnt fuel is the biggest issue on the petrol combustion engine today.

How often do we check the Millilitres of Fuel being delivered to the engine?

How the Electronic Injector works

The injector is located in the inlet manifold of the engine and sealed in between the manifold and fuel supply rail by Viton rubber seals. A fuel pump pressurises the system to normally about 2.5 bar.

The Engine Control Unit (ECU) gathers information from the various sensors located around the engine and using this information, the ECU determines the opening duration required for that combustion stroke. To do this, the ECU generates a current and transmits it to the solenoid of the injector.

The solenoid will magnetically lift the pintle valve needle from the seat of the injector, varying between 60 - 100mm. While the valve is raised, the pressurised fuel is forced through the orifice gap in the bottom of the injector, on to the pintle head or orifice plate and form a spray pattern shape as nominated by the head or plate design.

The injector will remain open for anywhere between 1 - 20 milliseconds, at a frequency of 3 - 125 Hz, depending on the engines requirements. When the current is stops, a small coil spring pushes the valve needle to the pintle seat and stops any further fuel from passing through. This process is repeated many time a second.

Due to demands for various fuel quantity deliveries and spray formations, Robert Bosch alone, produce over 1100 different injector part numbers.

The Electronic Petrol Injector Valve - Serviceable Parts

Unlike Diesel Injectors, Gasoline Electronic Injector is a sealed unit and cannot be dismantled or have any of its internal Mechanical or Electrical components replaced.

Only the external components and the internal filter basket can be replaced.

All rubber Fuel & Air seals should be replaced if injector are removed from engine.

Engine Related Problems

Recognise the symptom, what’s the cause?

• Starting Problems...Difficult to start, hot or cold or will not start at all.
• Poor Fuel Economy...Vehicle has good performance, but excessive fuel consumption.
• Excessive Exhaust Emissions...Failure on exhaust emissions, no adjustment available. Lambda or Catalyst exhaust failure.
• Idling Problems...Un-even idling, surging, misfiring, ‘pinking’ adjustment fails to resolve problem.
• Lacking Performance...Lack of power, flat spots, poor throttle response, car not performing like it use to.
• Poor Driveability...The car hesitates, ‘pinks’ under load, erratic performance and throttle response.
• ECU Error Warning Codes...Error code shows fault with Lambda or Air/Fuel mixture and checks show no fault.

Engine Related Problems

Symptom, Cause, Consequence, Results?

• Leaking Injector Valves will cause: Wetting of the manifold walls, that will cause Starting problems, Inlet Valve Gumming & Valve Sticking , Bore Wash, causing Loss of Compression, Lacquering of the Oxygen Sensor , causing slow Lambda response time & Clogging or Failure of the Catalyst Exhaust , causing serious loss of performance or non starting.

• Poor Fuel Distribution & Atomisation will cause: All of the above, plus Excessive Exhaust Emissions, Poor Fuel Economy, Idling Problems, Lack of Power, Poor Driveability.
• Un-even Fuel Delivery Rates will result in: Incorrect Exhaust Emissions, Lambda Sensor & Catalyst Exhaust Problems, Idling Problems, Lack of Power, Poor Driveability.

Fuel Spray Management

What is a good spray pattern?

See the cause, understand the problem.

• FAIR but weak.
• BAD Split spray pattern
• BAD Split spray pattern
• BAD Jetting on left side
• GOOD.
• BAD Feathering at top of spray

Fuel Delivery - Quantity & Distribution

The Fuel Delivery and the Fuel Distribution can simultaneously be measured and visually examined.

The Distribution is measured by the length of penetration into the delivery tube.

The ideal requirement would be that all the penetrations reach the same length.

An imbalance in the distribution length would cause a change in the Air/Fuel ratio and result in any of the afore mentioned symptoms.

Fuel Spray Management

New Injectors may not solve the problem

Correct spray patterns are critical to good performance, fuel economy, drivability and exhaust emissions. New injectors do not guarantee correct spray patterns, as this picture shows.

Fuel Droplet Formation - Correcting the Problem

Seeing the problem is easy, correcting it is not.

So what is the answer? Fitting new injectors? Flushing some chemical through the system? No!

THE ANSWER IS ASNU’S PATTENTED ULTRASONIC CLEANING PROCESS.

The only way to get your injectors back to AS NEW (ASNU) condition.

Ultrasonic Cleaning

The shape and design of a Pintle type injector is critical to the fuel Distribution & Atomisation

Cleaning ensures that the injector can function as it was designed.

Chemical Cleaning

Chemical cleaning only clean the parts that they touch.

Areas where the chemical has failed to clean will cause disruption to the fuel Distribution and Atomisation.

Chemicals only go one way as quickly - OUTWARDS!

Problems?

Now you can find the Cause of the Problem?

Now you recognise the need for Injector Diagnostics

Welcome to the World of ASNU