Injector class mixed up, hot starting issue

[aneesh84]

I own a C5 2.0 HDI 16v 136 2005.

I was having some hot starting trouble, so wanted to check up the injectors. (siemens VDO)

While inspecting the engine, I was surprised to find three Class 5 injectors and one Class 4 injectors. I was even more intrigued that in lexia the programming is set for class 4 injectors.

Since I own the car for past 3 years and am not sure of the car's history, do you think such mix up of injectors could have been done in the factory?

Should I try changing the injector class in lexia to class 5? Could this be a reason for the occasional hot starting issue?

[GiveMeABreak]

Injector classes won't be mixed at the factory - In fact, Citroen specifically say it is essential to fit injectors of the same class, although the injector 'carriers' can be a different class as long as they are configured in the injection ECU.

An incorrect injector class can cause problems with the particle filtration system according to the info I have.

I suspect somebody has changed one. The Siemens injectors also need coding - so beware of changing anything that may cause more problems until you get the injectors sorted.

[aneesh84]

I have a Left Hand Drive car.

How does the injector numbering work on the Lexia. Is the Gear side number 1 or 4?

[GiveMeABreak]

I'll need your VIN to confirm, post or PM it, but I suspect you you have the DW10BTED4 138 for the MK II with Siemens Injection variant:

Marking of the class ( as "e")	Correspondance
4	Minimum
5	Nominal
6	Maximum

[aneesh84]

I'll need your VIN to confirm, post or PM it, but I suspect you you have the DW10BTED4 138 for the MK II with Siemens Injection variant:

C5 MK II Siemens Injector Order.PNG

Marking of the class ( as "e")	Correspondance
4	Minimum
5	Nominal
6	Maximum

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

Thats right. I now have class 4 in in cylinder 1 and class 5 in the remaining. I checked these dont seem to have individual injector codes.

Probably a previous owner just got a class 4 injector in place of 5.

I changed all programming to class 5 in lexia. I guess its probably best to not try to fix something which aint broke, unless one class 4 injector could cause engine damage. I have no DPF. any advises?


The main problem I was having was a rare starting trouble when the engine was very hot (hot summer month or a steep climb). My suspect is high leakage in injector 4.

On one of these occasions when it wasnt starting (started after half an hour of cooling down), I managed to read the parameters:

Engine speed: 288 rpm
Cam crank synchronization: yes
Fuel pressure reference: 251 bars
Fuel pressure measured: 94 bars
Open cycle ratio Pressure regulator: 48%
Open cycle ratio flow regulator: 40%
Injected flow measure: 12.34 mg/stroke
injector flow correction, cylinder 1: 93.33%
injector flow correction, cylinder 2: 93.33%
injector flow correction, cylinder 3: 97.25%
injector flow correction, cylinder 4: 116.08%
Pre injection advance: -0
main injection advance: -0
injection time: 1.03ms
Engine coolant temperature: 100 degree celcius
fuel temperature: 81 degree celcius
measured air flow: 322 mg/cp
atm pressure: 788 mbar
turbo pressure: 788 mbar
egr valve open cycle ratio : 0%
egr throttle electrovalve open cycle ratio: 10%

[RichardW]

Fuel pressure reference: 251 bars
Fuel pressure measured: 94 bars

That's why it won't start - not enough fuel pressure to start injection (needs to be >200bar). WHY the fuel pressure is not high enough is another matter, but a suspect injector causing leak off at high temperatures is a good call.

[aneesh84]

Fuel pressure reference: 251 bars
Fuel pressure measured: 94 bars

That's why it won't start - not enough fuel pressure to start injection (needs to be >200bar). WHY the fuel pressure is not high enough is another matter, but a suspect injector causing leak off at high temperatures is a good call.

Yes I left it undisturbed over these last years since the issue only came when engine really hot and 30 minutes of letting it cool made it start. Finally I got an leak off test kit and Injector 3 has a high leak off.

Is this a common issue with these injectors? Can I buy a cheaper remanufactured one on ebay? Any advice.

[Niko]

Hi, did you fixed the problem with mixed injector classes?
I have volvo c30 with peugeot-ford 2.0d 136 hp engine. The car have a same problem like yours. When the engine is hot it wont start. Diesel pump and injectors are checked in stand and everything is ok, but the pressure in rail is only 100 bars on starter.
Like you I have 3 injectors class 5 and remaining one is class 4.
High pressure fuel regulator (this one mounted on the fuel pump) is brand new.
My question is to try to change only this injector which is class 4 . Any advices?

[aneesh84]

Hi, did you fixed the problem with mixed injector classes?
I have volvo c30 with peugeot-ford 2.0d 136 hp engine. The car have a same problem like yours. When the engine is hot it wont start. Diesel pump and injectors are checked in stand and everything is ok, but the pressure in rail is only 100 bars on starter.
Like you I have 3 injectors class 5 and remaining one is class 4.
High pressure fuel regulator (this one mounted on the fuel pump) is brand new.
My question is to try to change only this injector which is class 4 . Any advices?

In my case the problem was only when engine was really hot, particularly after climbing a mountain. I had checked with injector leak off kit, and it was Injector number 3 that had a huge leak off when engine was warm (though not so much on a cold engine, so the test must be done on a warm engine). This injector was Class 5 injector and the single Class 4 injector did not show excessive leakoff. So I do not see the need to change the Class 4 injector since it has been working pretty well. (although ideally one should not mix up classes but they have been driven like this for around 100K Kilometers and drive fine).

After using 5 bottles of injector cleaners and some italian tuneups, injector correction values have improved and the hot starting issue has also not been seen in some time. Last time I drove up a mountain there was some hesitation in starting but a few turns of the key and acceleration got it started. So I havnt bothered changing the injector number 3 as of yet unless the issue worsens. At least I have the problem diagnosed and I know what to change when needed!

[Niko]

Thanks a lot for the fast answer. In this case I will continue with other things , actually dont know else to check and will write why the problem is solved.

[aneesh84]

make sure you do the leak off test when engine is hot! if back flow is okay for all injectors, the issue for not starting can also be due to bad starter motor or low battery. keep us posted. thanks

[Niko]

Hi all, finally the car is ok. I started to make a little bit strange tests, after fuel pump and injectors were on the bench test. There is one old method to irrigate cold bottle of water under fuel pump when the engine is hot and to try to start it. Fortunately there was no result, because otherwise it will show you that the fuel pump is too worn out and when its hot it will appear some big clearances between pistons and it will be impossible for the pump to make the necessary pressure (200 bars) for opening the fuel injectors.
After forced cool down of the pump, I take ice from the refrigerator put it in plastic bag I start to test fuel injectors. I put the plastic bag right above each of it for 20-30 seconds, and surprise after I put ice above injector number 3 the engine started.
I drove the (all car not only the unmounted injectors)again in the same service and explained to the mechanics what I did.
In the beginning they didnt believe me about my ice test, but in a week later, they called me and explained me that on the test bench the fuel temperature is 55-60 degree but on the car the temperature is 80 degree. Thats why when they test the injectors they didnt catch the problem.
The problem was in piezo part of the injector, not in the mechanical valves in the injector itself. After certain high temperatures and time the piezo package "jams" in lets say open position and the injector unload fuel directly in cylinder during starting mode, thats why common rail wont make 200 bars pressure and the computer wont give a signal to the other injectors to open and the engine to start.

Thanks for the help and I hope I will help some other with my problem solution!

[aneesh84]

Thank you for the update. i am glad you solved your problem.

I also think i have got a workaround for my problem without needing to change the injector with high Leak off values. basically i just changed the radiator since some areas of the radiator felt cold to touch. after that i have done several tests and the car always started.

i guess the new radiator avoids the engine getting so hot so the leakoff from the faulty injector is still not big enough to cause the starting issue.