TDCI control unit replaced, engine won't start

Hello fellow DIY enthusiasts,

to the history:
I own, among other things, a Ford Focus 1.8 TDCI with 115 horsepower, which had problems with idling some time ago.
I had the car checked at the dealership, and they diagnosed a faulty injector. I had it replaced, and the car ran fine again. However, after about 2 more months, the engine started running rough again at low RPMs, as if one cylinder was intermittently misfiring. Therefore, I bought 3 more injectors (from a Bosch service center) so that I can have them replaced by a qualified mechanic at my convenience.
Last week, the car suddenly stalled late in the evening. The engine stopped while I was driving and wouldn't restart.
The next morning, I intended to have the vehicle towed to the workshop, but I decided to try starting the engine one more time. To my surprise, the engine started and ran perfectly all the way to the workshop.

Diagnosis: Faulty camshaft sensor!

Okay, I told the mechanic that he should replace this part and also replace the three injectors at the same time.

Then the master called me and said:

Initially, the engine ran perfectly smoothly and cleanly, and had good power, but then (during the test drive), one cylinder stopped working, so it was only running on three cylinders.

Diagnosis: Camshaft sensor OK, but now the engine control unit for the diesel injection system is defective. The fourth [item/part/etc.]. "The cylinder isn't receiving a signal, and strangely, there's no error code stored, and the yellow preheating light isn't illuminated either."

Since this part costs approximately 1000€ and the Focus is about 10 years old, I purchased a used and inspected engine control unit (ECU) and had the workshop install it.

Then the mechanic called me again and explained that he had installed the new ECU (Engine Control Unit), but now the car wouldn't start, and he wanted me to give him the old ECU back so he could reinstall it, which I did.

Then I took the engine control unit (ECU) to the workshop, and they immediately installed the old ECU, calibrated the injectors, and tried to start the engine, but without success.

Now the mechanics are at a loss, and I'm also out of ideas. Do you have any clues as to what might be wrong?

Best regards,
Werner.

bastianna wrote:

Do they have any clues as to what is wrong?

Hi Werner,

I'm not familiar with Ford, so I can only guess, but hopefully this helps: With VW, after replacing the engine control unit, the immobilizer would need to be adjusted. Otherwise, the engine would start but shut off after a second. I have no idea how Ford handles this, or whether the workshop has taken that into consideration.

With the reinstallation of the MSG, it would work again on VW vehicles (at least during the Golf 3 era), as long as no modifications had been made to the WFS in the meantime. But Ford could also handle this differently.

Greetings.
Guste.

Normally, the WFS (Windshield Wiper Fluid System) in Ford vehicles also blocks the starter. It's 98% likely that it's not related to him turning [something].
But actually, the expert at Ford should know that best.

Good morning, I don't think that's the WFS either.
But something was done differently, or something was forgotten, because the vehicle was running after the turbocharger replacement, but what was it?

One more thing, I just remembered.
Out of sheer helplessness, the "Friendly" forces had reinstalled the injectors.
(The current state is with the OLD control unit and OLD injectors.)
hoping that the engine would run again in its original condition.

Unfortunately, I have to work, otherwise I would be there and could ask Jung a lot of questions.
Are there any Ford or Bosch enthusiasts who might be able to help out, as I really need this vehicle?

Best regards,
Werner.

Okay, it's me again. The workshop spent the entire day working on the car today, trying to find the problem, but unfortunately, they were unsuccessful. The engine just won't start.

I really need your help. They might even want money for all the trouble they're causing!

Best regards,
Werner.