Injector Leak Back Test, how do I perform one?cross graphic

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Pressure loss within a common rail fuel system can often result in one or more of the following symptoms,

  • Hard or difficult starting
  • Erratic or uneven tick over or idle
  • Lumpy running and hesitation on acceleration
  • Smoke on tick over or acceleration
  • Lack of power or even a total shut down of the system

One of the main reasons for pressure loss is due to excessive fuel being returned to the fuel tank, also known as back leakage. Once the injector/s suffers from excessive back leakage, the fuel pump cannot generate enough pressure to enable the system to operate. This is more pronounced at starting or tick over due to the fact that the pressure generated by the pump is directly related to the engine's revolutions, which are lower at, start and tick over. In a colder climate the engine rotates slightly slower thus lowering pump pressure whilst with warmer fuel the viscosity is thinner thus allowing worn injector parts to leak more, increasing back leakage.

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Injector nozzle tips swell and blow off, why?cross graphic

The first problem with modern day engines is that if the injectors do not seat correctly in the cylinder head combustion gases escape pass the side of the injector. The ECU picks up a problem with the running of the engine and then tries to compensate by sending more fuel to the offending cylinders thus causing a "over fuelling" situation which in-turn causes excessive heat thus weakening the nozzle. This is evident by noticing one of the copper washers disfigured and "melting" up the injector.

Another problem is the possibility of water in the fuel as this is another reason why nozzle tips "blow" off, have a look at this article "Diesel Fuel, Air Vapors And Your Engine Part 1 of 4 By Steve Pollock"


A quote out of article is,

"Probably the most damaging area affected by entrained air/vapors is the engine's fuel injectors. One of the functions of diesel fuel is to lubricate the injectors as they are working. As the entrained air/vapor passes through the
injector it is not providing complete lubricity.
This lack of lubrication for the injector's barrel ad plunger becomes even more critical with the tight tolerances and high fuel pressures used in today's injectors. The entrained air/vapor creates a metal on metal situation. Over time the plunger can start to stick and as it wears, factory tolerances are lost. This causes fuel blow- by in the injector. According to Caterpillar's handbook, entrained air/vapor can create up to 50% greater forces by the plunger on the injector tip. As the fuel comes out the injector tip under high pressure the entrained air/vapor can also act much like an acetylene torch, eroding the injector tip. These two things in combination can lead to the injector tip breaking off."

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Injectors repaired, are they as good as new units?cross graphic

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A repaired unit is an old unit that has been stripped, inspected, cleaned, some internal parts replaced, reassembled and then tested. As some original parts are reused the completed unit will not have the same life span as that of a new unit.

Payment methods, are my card details safe, what is PCI DSS?cross graphic

As we are dedicated to ensuring that your details are kept safe and confidential we are compliant to WorldPay PCI DSS

PCI DSS is the Payment Card Industry Data Security Standard, and this is a worldwide standard that was set up to help businesses process card payments securely and reduce card fraud. The way it does this is through tight controls surrounding the storage, transmission and processing of cardholder data that businesses handle. PCI DSS is intended to protect sensitive cardholder data.

Validation Certificate

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PD 8V Nozzles, how do they compare?cross graphic

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This is an updated PD 8V Nozzle flow comparison chart. The results are the fuel delivers from each nozzle tested in the same injector and using the same test process.

There seems to be a miss conception about flow rates and percentages, for example you will see that the Firad +80% does not flow 80% more fuel than a stock nozzle

Stock 150 Bhp Bosch OEM nozzles delivers 23.8 Cms, with the same test the Firad +80% delivers 32.2 Cms which is a 37% increase in fuel.

I believe that some manufactures use the percentage to represent a hole size measurement but they all keep the manufacturing process to them selves so we might never know. The important thing for me is the end result of what the nozzle and injector body is capable of delivering.

It is more important to measure delivery of the complete injector as it will be a true reflection of it performance in the engine.

Should you have any questions or are able to offer relevant information please contact or go to our face book page https://www.facebook.com/uniteddiesel

The chart is in the file download/

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PD and VE injectors, how do you do them?cross graphic

When enquiring about injector nozzle replacement, either standard or high performance or the supply of service exchange units it is important that you deal with a company that has the experience, knowledge and equipment to do the job correctly.

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PD Injectors, can you test them?cross graphic

We specialise in all aspects of PD diesel injector testing, repairs and upgrades. As we have the experiance, equipment and passion for PD injectors we can test, repair and upgrade your PD injectors.

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Performance injectors, my mapper wants to know what my injectors deliver.cross graphic

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We are pleased to be able to offer a custom “Injector Mapping Chart” for common rail injectors. This is especially helpful to any tuner who is in the process of remapping a modified vehicle. Whether there has been a bigger turbo, higher flowing injectors or a larger inter-cooler fitted, by being able to see what fuel deliverers are produced will allow for a more accurate and effective tune allowing for optimum performance.

The “Injector Mapping Chart” is totally custom so we can add or alter parameters to suit your needs. We are also able to compare delivers from stock and performance injectors so that the increases can be used to match other performance enhancing products.

Should you wish to know more please do not hesitate to contact us.

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Plug and Play Re-maps and Files Sold on E-bay, any Good?cross graphic

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There are a number of basic power upgrades available in a plug and play format or are downloadable from the web. Whilst some of these items can offer slight increases in power, they operate by merely adjusting a specified signal within the ECU by a set tolerance. It's impossible to compare these inferior upgrades with a full rolling road re-map which measures and adjusts hundreds of signals and data files within the ECU.

We advise that these generic files and unsupported devices for sale on the web should be avoided at all cost. We've seen too many customers come to us after a bad experience - and there was no one else to turn to either. We're always happy to advise on your tuning needs.

Service Exchange Units?cross graphic

Service exchange units, either new or repaired are units that we send to you and then once fitted you return your old units back to us. If you do not return your old units or they are returned damaged then the surcharge price as indicated on your original invoice and return note will be charged to you.

Service exchange units will be supplied with a 'core return note' an addressed pre-paid return label. (U.K. mainland only) Your old units need to be returned to us, in a repairable condition, within 30 days.

To return 'old units', simply place in the box used to supply the new units with the 'core return note', stick the pre-paid addressed label on the outside and take to a post office. Please obtain a 'proof of postage' receipt when returning old injectors, as the onus will be on you to prove that the old units had been posted should they be lost.