Procedure: Adaptation of 1.6 TDI Commonrail injectors (Siemens PCR 2.1 )

Injectors in modern diesel engines are relatively expensive. So it's important to be sure that they work properly after replacement. The 1.6 TDI Commonrail engine (EA188 generation, Siemens PCR 2.1 ECU) is no exception. Injectors for this engine (03L130277B, 03L130277S, A2C9626040080) now cost around €400, so it's best to make sure they last as long as possible.

What is injector adaptation?

Injector adaptation, or more precisely, the adaptation of injection flow rate deviations, is a procedure for resetting the values stored in the ECU for the flow rate deviations of each injector. In simple terms, as an injector ages, its ability to inject the exact amount of fuel required diminishes. These injection accuracy errors (deviations) have been known in advance since the injectors were first designed and tested. Correction factors are therefore introduced and follow graphs and tables precisely elaborated by engineers during engine mapping development.

What is the role of correction factors for injection rate deviations?

Correction factors are a way of “extending” the life of solenoid injectors. In simpler terms, this factor works like a kind of cruise control for the injector: the older the injector gets, the less precise it becomes in injecting the right amount of fuel. The table according to which the correct correction factor is chosen exists in the engine map, and the exact location of the injector's current value is stored there (like a sportsman who knows his usual performance).

When you replace one or more injectors, it's like replacing one athlete with another on a team: you can't know in advance what performance the new athlete will have, so you have to put him or her through a few tests to find out how well he or she performs and what result you can expect. Injectors work on the same principle. 

When should an injector adaptation procedure be carried out?

After replacing one or more injectors with new OR used ones.

If you've already dismantled a working injector (to carry out another repair, for example) and put it back in its original position, you don't need to carry out this procedure.

What does the adaptation procedure do for my engine and injectors?

As indicated in the previous example, the adaptation procedure allows you to determine the performance of an injector. Even between 2 new injectors, their “performance” is not identical. In injection, we're talking about differences of the order of tenths of a mg, i.e. variations / deviations of 0.00001g! This heightened precision calls for correct calibration from the outset.

How do I adapt an injector?

First of all, of course, if the injector is faulty, it has to be replaced. The procedure for replacing an injector can be found here.

After changing a faulty injector, and before restarting the vehicle, connect the VCDS/diagnostic tool and code the injectors. With the VCDS, go to Engine, then Secure Access. Enter the code displayed, and the secure access will be unlocked.

Then go to Adaptation, and search for Injector coding with the corresponding injector number(s) (e.g. Injector coding 1). Then enter the new codes (on never-rebuilt injectors (new/used), 6-character code (IIC code in the picture); on rebuilt injectors, the codes can be found on the injector test sheets (supplied by the vendor).

Warning! You must not mix up the codes (mostly written on test printouts) of rebuilt injectors (if you're fitting several rebuilt injectors at the same time), otherwise the software won't let you register them (if the wrong code is entered). Once all changed injectors have been coded and registered, you can disconnect the VCDS/diagnostic software.

Adaptation:

Caution! Do not perform this procedure on VCDS: it is dangerous, loops if incorrectly started, and damages injectors and solenoid coils, especially those on used injectors. The procedure for adaptation YOU SHOULD do is as follows.

• Start the vehicle, then wait 5-7 seconds for the oil pressure to build up and the idle speed to stabilize (in cold weather, wait at least 15 seconds, until the RPM's drop back to around 900-1000 rpm - when cold start returns to lower RPM range).

• Then rev the engine up to the rev limiter (at standstill, the limiter, also known as the soft cut, is around 2300 rpm) without engaging a gear (if you have removed this limiter during a remap, keep your foot as evenly on the pedal as possible to stabilize at approx. 2300 rpm). Maintain this engine speed for about 1 minute.

• Then release the accelerator pedal and let the engine idle for 1 minute, without touching anything.

• At the end of the idling stage, you should drive off without switching off the engine in the meantime. As soon as you take off, go into 3rd gear, and accelerate 5 times, raising engine speed from ~1000 to around 3000 rpm. Accelerate and then let the engine speed fall back to around 1000 rpm before accelerating again. The vehicle won't start out very fast, but without this adaptation in the lower revs, the engine risks over-consumption at these speeds, or even stalling when hot and on DPF regen. For the duration of the 5 accelerations, you should not change gear between accelerations, nor should you touch the clutch during this procedure.

Caution! DO NOT, UNDER ANY CIRCUMSTANCES, PRESS THE BRAKE when revving down, unless you're in danger or putting someone else in danger!

Among other things, this rev-down setting enables post-injection adaptation, i.e. DPG regeneration. If this is not done correctly, the car may cut out during hard braking when you brake, as the adaptation will not be done correctly.

After these accelerations, drive for 5-10 minutes in the “usual” way, i.e. as you drive the vehicle every day. This pre-adjusts the last flow deviations and adapts them to your driving style (don't drive like a rally driver either, the aim is to adapt the short-term memory of the fuel trim values to your usual driving style).
Once the procedure is complete, you should hear much less injector noise/knock, and the engine should run smoothly at all engine speeds.

My injectors are still knocking, but a lot less. Is this normal?

As this procedure also erases the adaptation of long-term fuel trim, it will take several hundred kilometers before the adaptation values become stable, so at certain engine speeds you may still hear your injectors making a little noise.

End of procedure.

Congratulations, you have correctly adapted your injectors. The (adaptation) process starts automatically when you encode an injector, which is why if the procedure is not followed, injectors, even new ones, knock or make car smoke.

It's best not to drive with a non-adapted injector, otherwise it will clog up, inject too much or too little fuel, get damaged (very shortened life), the pollution control elements such as the DPF (Diesel Particle Filter) or the EGR valve (Exhaust Gas Recirculation) will clog up much more quickly, possibly causing internal engine damage (holes in pistons, cracked valves, etc.), and costs and/or damage to the engine. .), and unnecessary repair costs and/or loss of time.