Injectors were cleaned! Really?

Quite often the call for help includes the following description: “..the injectors were cleaned, then I put them back..”

In such cases, I usually ask several questions, and according to the answers from the customer, we conclude that the customer is cheated. Not a one time the cleaning of the injectors has been done! How so? Read further!

A regular user of the car doesn’t know (and he doesn’t have to know) that the injectors get clogged and they have to be cleaned. If such service is offered by the company (sometimes even – a large and solid company, a cooperation partner of some large, for example, German company), the customer has no reason to not trust it – they know, what they are doing and for what they charge (and receive) money.

But – about everything from the beginning.


In the image: used piezo injector

When I ask people, by what criteria they evaluate the cleaning of the injector, usually get an answer – before cleaning the injector was looking like one in the image (black), but when it got back – clean! The result is obvious!

Unfortunately, this is not a criterion. New (clean, shiny) injector becomes black, ugly and burned during several hundreds of km. But then, most interesting happens – the appearance of the injector almost doesn’t change during its lifetime! Why so? The construction of the injector is made in such a way, that the fuel, which flows out, cleans the injector automatically! This feature is mentioned even in Aftersales materials of the BMW. In any case – fuel from the injector flows out with a pressure of 200 Bar. This is a large pressure, fuel flows out with high power. Soot can do nothing to such jet of fuel. Yes, of course, it is nice, if the injectors are cleaned also from outside, but – not the shining outside is the point of cleaning!


Where then the injector should be cleaned? Now I will compare the cleaning of the injectors with an everyday thing. Each of us has had a runny nose. Each of us knows, that then the nose has to be released. Exactly in such way, the injectors have to be cleaned – blowing thru them a cleaning reagent, cleaning them from inside. Exactly in the inside of the nozzle, some micropart can get stuck (it sticks to the walls of the nozzle) – it has to be “blown” out.

Below I will mention some more common “cleaning” types. Smart people buy cheap ultrasound cleaning baths and try to “clean” – earn money.

1. method. The injectors are placed in the ultrasound bath and get “clean”. FAIL. Why? In such a way, only outside of the injector gets clean. The cleaning liquid doesn’t even get inside the injector! Wasted time and money!

2. method. The injectors are placed in the ultrasound bath, connected to the activation module (they are opened periodically). FAIL. The nozzle holes of these injectors are so tiny, the pressure of the cleaning liquid in the 10 .. 15 cm deep ultrasound bath is much too low for the cleaning liquid to get inside the injector and clean it. Also, the injectors have to be supplied with a 150V voltage – it requires a special and expensive management module. Majority of the “cleaners’ connect the injectors to the 12V voltage (as “regular” injectors) – the injectors don’t even try to open.

3. method. Improved version of the previous method. The cleaning liquid is pushed via the injector with a pressure of 5 Bar. FAIL. Of course. better than nothing, but also a 5 Bar is a miserable pressure for piezo injectors. Such pressure is not enough to test (before/after cleaning), not even talking about flushing out the dirt.


What does the cleaning of injectors mean?

The fundamental requirement: cleaning of the injector consists of 3 stages:

a) full diagnostics of the injector;

b) mechanical cleaning of the injector;

c) full diagnostics of the injector and evaluation of the result.

Purpose of the diagnostics of the injector – to understand, what is “wrong” with the injector. Problems can be caused by microparts stuck in the nozzle, and also by other defects, for example, microcracks of the piezo element and other troubles.

Defects of the piezo elements will not be solved by any cleaning! Diagnostics of the injector (leaks, the shape of the bundle, evaluation of the bundle ) have to be done by 200 Bar pressure – it is very important. By lower pressure, the largest number of leaking injectors stops leaking – the defect hides!

Cleaning of the injectors: with sufficient pressure (100+ Bar) via injector (the injector opens and closes periodically by supplying an appropriate voltage of 120 .. 150V) the fluid is pushed thru.

The aim of the repeated diagnostics – measuring of all parameters of the injector (electrical, delay, flowrate) and evaluation of leaking. Evaluation of leaking (in closed condition) have to be evaluated with the pressure of 200 .. 250 Bar.

I know, that the Carbon Zap equipment provides the required functionality. Here, more detailed info, what kind of tests are performed: here So – regarding each cleaned injector you would have to receive 2 diagnostics reports:

a) one – data regarding injector before cleaning;

b) second – data regarding injector after cleaning.

If there are no such reports – the “cleaning” is meaningless! How can you know, that exactly the micro part was a cause of the incorrect performance of the injector? How can you know, that the defect is fixed now? Without exact measurements, it is not possible to indicate it!

I hope, that this entry will help you to choose an appropriate company to clean the injectors!

And finally – a reply to the intriguing theme: what questions do I ask the customers?

I asked – did the cleaning company issued a report for each injector? Just that simple. The diagnostics report would allow understanding, in which modes and how the measurements of the injector parameters the injectors are measured, is the leaking of the injector confirmed, is this leaking (at least for the exact moment, in the lab) disappeared. Unfortunately, in none of the cases (several tens), the customers haven’t got any information. Unfortunately, not in one case were the positive results – the injectors continued to leak.