kazeMotorsports
Member
The “ I ” In EFI
Very high demands are placed on Electronic Fuel Injection (EFI) equipped engines with regards to: Starting, Performance, Drivability, Fuel consumption and Exhaust gas values. Fuel Injectors have a decisive influence upon ALL of these characteristics, and must therefore comply with stringent quality standards. Essentially the following factors must be considered.
1. Precise fuel delivery at all rpm ranges.
2. Good linearity, the difference in fuel delivery between the injectors must not exceed the specific tolerance value.
3. Good dynamic flow range. (Pulsation)
4. Good fuel distribution and fuel atomisation.
5. Valve closing and seating to prevent fuel drip or leak.
The Injector Valve has the finest tolerances of any mechanical component on the engine.
We are constantly checking Milliseconds, Milivolts and Milliamps. When do we check Millilitres? Un-burnt fuel is the biggest issue on the petrol combustion engine today, how often do we check the Millilitres of Fuel delivered?
We change Air Filters, Oil Filters and Fuel Filters, how often do we change Injector Filter? The fact is all filters are meant to be choked with contaminants and to be replaced within certain period. Clean balanced injectors are a key to performance and fuel economy in any EFI engines. (Car, Motorcycle, Marine, etc)
Engine Related Problems, Recognise the Symptoms
1. Starting Problems - Difficult to start, hot or cold or will not start at all.
2. Poor Fuel Economy - Vehicle has good performance, but excessive fuel consumption.
3. Excessive Exhaust Emission - Inspection failure on exhaust emissions and no adjustment is available. Lambda or Catalyst exhausts failure.
4. Idling Problems - Erratic and uneven idling and adjustment or cleaning to idling valve fails to resolve problem.
5. Lacking Performance - Lack of power, flat spots, poor throttle response, car not performing like it should or use to be.
6. Poor Drivability - The car hesitates, jerking, pinging under load, erratic performance and throttle response.
7. Check Engine (MIL) Fault Codes - Error code shows fault with Lambda or Air/Fuel mixture and physical checks show no fault.
On the latest generation of Lambda(O2 Sensor) controlled, Fuel Injected Engine Management Systems(OBD-II), correct diagnosis of the complete system is no longer an option, it’s a requirement. As these systems are using “Closed Loop” design where all the components in the system contribute to the engines correct and efficient running, then the correct diagnostic programme should cover all the components related to the complete Engine Management System, not just some of them.
The Fuel Injectors and their individual performance are now one of the major components to look into when diagnostically and analysing any system for “combustion related” problems, especially if problem is relating to Engine Performance, Fuel Economy and Exhaust
Pollution, Lambda or Catalyst failure. Another type of EFI engine on the market is Gasoline Direct Injection (GDI) engines. These engines are running extremely lean air fuel ratio, up to 40:1 at times and placing the GDI injectors in the combustion chamber has already started to cause a problem from day 1 onwards, due to the fact that the most dirty part of the engine is the combustion chamber.
ASNU(Pronounced as “As New”), have created a system called “Injector Diagnostics”, a Testing & Servicing programme where the Injectors Valve Seating, Coil Dynamic Resistance, Fuel Distribution, Fuel Droplet Formation, Fuel Atomisation and Fuel Delivery, are all visually, physically checked and tested as a starting point rather than a last resort. The injectors will be cleaned using a special biodegradable liquid and ASNU’s custom tuned Ultrasonic bath. The rubber sealing o-rings, plastic protection caps and filter baskets are replaced before re-testing, ensuring all the injectors are performing as a matched, balanced set. The before and after results will be presented in a detailed report sheet to the owner or mechanic.
Without “Injector Diagnostics”, it is impossible for workshops to correctly, economically or efficiently solve problems with Fuel Injected engines. Servicing Injectors will also save time and money on Service and Repair bills, prolong the life of Inlet & Exhaust Valves, Piston Compression Rings, Lambda/Oxygen Sensors and the Catalytic Exhaust System.
ASNU is approved World Wide by Robert Bosch GmbH and Delphi Automotive.
Chemical Cleaning, Fact not Fiction
These additives also coat the internal components of the injector, restricting the fuel flow and pintle travel. The coating also increases the surface tension as the fuel exits the injector, causing a drag effect and by doing so, creating a larger droplet of fuel.
They are more likely to clean up the fuel tank than anything else in the fuel system. Loosening up dirt in the tank and choking up your fuel filter, which causes it to bypass fuel without proper filtration. This places more dirt in the injector filter baskets and restricting fuel further.
The “Better Performance Effect” these chemicals provides, if present, only last for that tank of refill. The “pour into the tank” chemical cleaning craze has never been expected to progress to this kind of level. You can find dozens of such chemicals on the shelves if you have been to an automotive supermarket in Japan and USA or even locally. Even fuel companies like Caltex, Honda, 3M also sells them on the market. Then of course some of them even shows you the before and after pictures claiming to “clean” combustion chambers, intake valves and fuel injectors. It will never happen and the improvements are largely due to the upper cylinder lubrication these cleaners has. The best F.I cleaners I have ever used did improved the performance of my engine slightly but I guess it is partly due to the long drive up to KL. Long drives works better than any cleaning agents available on the market as it clears the excess carbon away from the combustion chamber! However, cars running on carburettors will see some benefits with these in-tank chemicals. The main reasons why in-tank cleaners don’t work on injector is simple. Number 1, Fuel will be spraying outwards in a cone shape, the pintle that regulates the fuel flow is practically untouched by the fuel. Number 2, there is no way the filter basket inside the injector can be cleaned and they need to be replaced with a new one. Assuming they do have some cleaning effects, what makes you think all 4 or 6 injectors will be 100% cleaned? If they are not individually 100% cleaned do not even bother to clean them in the first place, we will touch on that later.
In-tank cleaners is either too low in concentration or too heavy which fouls up your expensive sparkplugs. It seems like all automotive sectors recognises the problem of dirty injectors which resulting in bad combustion, poor performance and higher fuel consumption. However, instead of providing a solution to the problem they are profiteering from products that don’t work and even add on to the problem. The only solution to a set of clean, balanced set of fuel injector is to introduce the Injector Servicing Program into our scheduled vehicle servicing intervals. The only machine that can do this properly is of course by ASNU.
OBD2 ECU & F.I Relationship
Our modern engine management system or OBD2 ECU will be constantly monitoring the final combustion gases in the exhaust system to ensure optimum fuel economy and emission control. The reading taken using an Oxygen Sensor(O2) or technically lambda sensor, which feeds the ECU the Air/Fuel ratio of the exhaust gases. The ECU will make corrections in the sub-map so that the Stiochiometric or idea 14.7:1(14.7 parts of air to 1 part of petrol) ratio is kept in check during closed-loop operation(Fuel Economy & Emission control Mode) which happens mainly at idle, light loads or cruising time.
This advance system has a “loop hole” that owners do not realised and manufacturers do not want you to know. Take a general 4 cylinders car as example A, the idea 14.7:1 ratio is the average of all 4 cylinders. IF all 4 cylinders fuel injectors are balanced, it should have 14.7:1 ratio throughout the 4 cylinders, which the ECU will, need minimum fuel trim. Assuming number 1 injector has a little bad spray pattern and its reading is 13.0:1, the other 3 still reads a healthy 14.7:1. The lambda will read 14.3:1(rich) on average and it will lead to the ECU reducing fuel to all 4 injectors simultaneously giving a reading something like this, 13.4, 15.15, 15.15, 15.15 or RICH, LEAN, LEAN, LEAN but the lambda will still be telling ECU Air/fuel mixture is Stiochiometric 14.7 or IDEA!
Another common example B, is clogged injectors. Say, only number 1 injector has average spray pattern but clogged and its reading is 16.0:1, the other 3 still reads healthy 14.7:1. The lambda will read 15.0:1(LEAN) on average and it will lead to the ECU increasing fuel to all 4 injectors simultaneously giving a reading something like 15.6, 14.4. 14.4, 14.4 or LEAN, RICH, RICH, RICH but the lambda will still be telling ECU Air/fuel mixture is Stiochiometric 14.7 or IDEA AGAIN!
These bad injectors scenarios are KILLING your engine softly day by day. You can use the same method of averaging to create the scenario that you want to visualise in your 4 cylinders now. The good news is car manufacturers have set certain tolerances in their ECU parameters in regards to Air/fuel mixture to compensate for these errors during open-loop operations where high load and acceleration happens.
Lambda Reading Vs ECU Tuning Relationship
Now let us get interesting and focus on what is happening to the precious cars of enthusiasts when it is tuned with piggyback fuel controllers or even standalone ECU. I shall cover mainly on open loop tuning which most of us does to gain power and some to save fuel.
In earlier example A, the cylinders read RICH, IDEA, IDEA, IDEA. There is just little chance to get the most power out from this engine as just when 3 of your cylinders are tuned at the Air/Fuel ratio just right for power, no. 1 cylinder will be too rich. Even using wide band lambda, the programmer would not be able to know what is going on in the 4 cylinders since he is targeting for a certain A/F ratio, e.g. 13.0:1 when it is only an average of the 4 cylinders. For those tuning for optimum fuel economy it can only spell disaster for the engine! Assuming the programmer is targeting at 14.6:1, he will need to reduce fuel simultaneously to all 4 cylinders giving a reading something like this, 13.2, 15.13, 15.13, 15.13 which will give him a reading of 14.6:1 on his thousand dollar wide band lambda system. The car owner will be lucky if the engine starts to detonate at those lean burning cylinders and the programmer will target a richer Air/Fuel Ratio instead so that the engine would not need an overhaul within 6 months.
In example B, where injectors clogged up will be another scenario. Those interested can private me and we can discuss this in chat rooms.
Ever wonder why two same cars in rather new condition with the same bigger turbo, injectors, fuel pump, intake, exhaust and ECU programming cannot achieve the same power output? The main difference that sets them apart is in the combustion process and the key lies in the variance of the fuel injectors no matter how much they cost. This question puzzles even some reputable computer programmers and tuners. I do not think it is their fault but due to the lack of proper F.I. diagnostic test bench, there is just no way to know!
