New injector

[krikan]

Hi all

Car went into limp mode. Diagbox showed something like 'high resistance cylinder 2'. Measured the resistance on the injector, which was lower than the others. Replaced the injector with a brand new (VDO/Siemens/Continental). Recoded in Diagbox by entering the code written on top of the new injector, which was accepted in Diagbox. Runs decent, a little bit of wobbling around 1000-1200 RPM and at >2200 RPM. Diagbox now says fault code P12A4 (local/permanent fault 'Injector injects too much or remains jammed in open position, see below two screenshots:

After a bit of driving, the car show the ABS/ESP fault (engine torque not cleared fault), which I am sure is directly caused by the injector/cylinder fault. After turning off the engine and restart the car runs decent again until the fault appears again.

See below screenshots showing the cylinder injection time etc. at idle and at 2400 RPM. NOTE - these screenshots are taken before the ABS/ESP fault will occur.

As you can see, the cylinder injection time is off (0.72 vs 1.10-1.10-1.16 ms). At 2400 RPM cylinder injection time is spot on equal for all cylinders.

Then, after I have driven a little and the ABS/ESP fault has occured, cylinder 2 will now read 0 ms and I can confirm that the ECU has turned it off completely as a sort of safety measure, I guess.

VIN: VF7**************[VIN obfuscated, can be read by forum staff]

Any ideas on what to do next? It seems a little odd that both the old injector AND the ECU/wiring or something else happened at the same time. And now, with a new injector I get this new P12A4 fault, which is probably the culprit now.

[GiveMeABreak]

Are you sure you coded it correctly and that the correct injector part number was used for this engine? These injectors should only require a classification Code which is 6 characters.

The fault would indicate this is still a possible cause:

Fault Code:	P12A4
Description of Fault:	No. 2 cylinder : Injector injects too much or remains jammed in the open position. The correction made to the fuel flow drift of injector 2 is higher than the maximum threshold. At least one of the following conditions must be fulfilled - Ignition switched on - engine running
Conditions for Fault to clear:	Driving for 5 minutes
Downgrade Modes whilst Fault is active:	Closing of the EGR (exhaust gas recycling) valve Reversible deactivation of the vehicle speed limiter Reversible deactivation of the vehicle cruise control Deactivation of the "easy-move" (electric parking brake) functionality Function for limitation of the static torque for the protection of the gearbox Deactivation of taking account of the tight spot information Switching of the turbocharging pressure regulation to controlled mode Cutting of fuel injector 2 Switching to fuel "normal reduced flow" mode Deactivation of the request for regeneration of the particle filter from the diagnostic tool
Symptoms:	Jerking/stalling Engine acceleration at wrong time Noise Slightly higher fuel consumption Starting problem Smoke from the exhaust Lack of power
Suspect Areas:	Fuel injector 2 Injector classification Fuel return

[krikan]

Thanks for your reply

Yes. I double checked the code many times when i entered it:

[Paul-R]

Did you count the cylinders from the correct end? PSA engines number from the GEARBOX end of the engine not the water pump end as most other engines do.

[krikan]

Thanks.
Yes. Nr. 2 from the right, standing in front of the engine. The old injector also had the same code on it as the one I deleted and recoded in Diagnox. In addition, I tested nr. 2 by unplugging the wires, when the engine was in ABS/ESP mode and it was indeed not working (RPM unchanged).

[krikan]

Could it be caused by a newer injector and older ECU software not working correctly together?

[wheeler]

I would swap injector 2 with one of the others & re code them to the appropriate cylinders, re check it & see if the fault moves to the different cylinder or stays in the same position, Dont rule out the new injector having a fault.

Also, unplugging an injector on a running HDi engine is not a good idea, if it has piezo type injectors (i dont know if yours does) this can flood the cylinder with fuel & cause serious engine damage.

[krikan]

Ok. Good suggestion. I will try that. Just need to order some new washers then.
Thanks for letting me know that it may not be good to unplug injectors on a running engine.

[krikan]

I have now switched the new injector in cylinder 2 with the one in cylinder 1. Same fault, but now at cylinder 1 instead.

What is your take on this? I am 100% sure about entering the correct codes and have also switched the two injector’s codes of course.

I would guess either a faulty injector or a compability issue between the new injector and the ECU. Faulty factory new injector seems very implausible?

Should I buy a used injector and test maybe? Any other ideas? I can’t update the ECU myself can I?

[Paul-R]

Why do you think the ECU needs updating?

[krikan]

I really don’t know if it could make sense to update the ECU. I just thought that there could be one of three reasons for the fault:

1. Wrong injector code
2. Faulty injector
3. The ECU/car does not recognise the type of injector or the code

I have no idea about what an ECU update does.

I just ordered an original Citroën injector as a last resort. Let’s see if that works. The first one I bought, which may be faulty, is VDO/Siemens/Continental. I will try to return that.

[krikan]

I have now tried with a new, original, injector. Exactly the same fault. I guess I can rule out faulty injector.

Is there any procedure for calibration or similar that I need to go through? ‘Complete programming of the injectors’ was performed 1000 km ago, it reads diagbox.

[krikan]

UPDATE

I had the car by an authorised Citroën repair shop today. They tried, more or less, the same is I have already done. They also said that updating the ECU would not solve the problem. They also said that they would always change all 4 injectors at the same time.

Could the problem be that the new injectors are so clean that they inject a lot more fuel than the others (which are probably about to reach the end of their lifespan), causing the ECU to compensate a lot for the new injector, restricting fuel to it? Thus the 'ECU' thinks that the new injector is stuck in open position and injecting too much fuel.

[Doo]

UPDATE

I had the car by an authorised Citroën repair shop today. They tried, more or less, the same is I have already done. They also said that they would always change all 4 injectors at the same time.

Could the problem be that the new injectors are so clean that they inject a lot more fuel than the others (which are probably about to reach the end of their lifespan), causing the ECU to compensate a lot for the new injector, restricting fuel to it? Thus the 'ECU' thinks that the new injector is stuck in open position and injecting too much fuel.

I had a slightly similar issue with our DV6. I put 2 injectors in, then 3 then 4, after which the car ran like a Swiss watch. It was leaking diesel and running poorly.

I bought re-con injectors from Darwen Diesels in Bolton, UK. I think they were around £125 each inc delivery. The car is in use every day and without issue.

[krikan]

Thanks a lot for your reply Doo.
I live in Denmark and there is no real market for reconditioned injectors here.
Based on your reply, I will order 2 more injectors so I have 4 new in total. That’s around half of what my old car is worth Might try putting in 2 injectors first, before the last 2 arrive.
Did you notice an improvement after putting in 2 injectors as well, or was it only after all 4 was replaced?