2015 C4 BlueHDI Misfiring

[DHallworth]

Evening Gents,

My wifes C4 is giving us some grief at the moment.

It’s a 2015 1.6 BlueHDi. The VIN is VF7**************[VIN obfuscated, can be read by forum staff].

Intermittently, for the last 12 months, very occasionally it has felt like it’s dropped a cylinder and it’s been running on 3. It’s always cleared as quickly as it’s done it and there’s never been any fault codes stored in the ECU.

As of today, it’s decided to spend more time on 3 cylinders then it is doing on 4 but there is still no engine management light and no fault codes stored.

I wondered about an injector, however, reading online it seems these injectors seem to fail completely rather then cause problems.

The fuel filter has been changed as it started to exhibit symptoms when under load such as on a hill on cruise control at 70. Tonight though, it’s barely driveable sitting at 55mph and whilst it was sitting idling it was on 3 one minute and 4 the next. Other than trying to read the correction values for the injectors, or unplugging them one by one as it’s dropping onto 3, does anybody have any suggestions where to go next with it?

Thanks,
David.

[DHallworth]

This morning, other than it’s normal small hiccup, it’s back to normal.

It’s getting to the point I don’t trust it for her to go out with the little one now though so need to try and fix it. Think I’m going to have to order a new Lexia interface so I can get the newer software to work for me.

David.

[RichardW]

Seems likely it's an injector, David. Surprised it hasn't thrown a fault though if it's shut one down! Don't unplug them when it's running, should they be working, they can be stay in the open position and hydrolock the cylinder!

[xantia_v6]

When you have a Lexia on it, check the fuel rail pressure when the fault is present.

[Paul-R]

What version of Diagbox are you running? Is it a full chip interface?

[DHallworth]

Tried Diagbox again, mine is too old to talk to this car. I think it’s V7.06 but it’s an older interface so probably won’t run the newer software.

I’ve spoken to a friend who is lending me a tool that will talk to it tomorrow.

I’ve also ordered a new injector from PF Jones so that I can replace it whilst I’ve got his machine if I need to. If not, I can return it.

Fingers crossed I can put an end to it as when it drops a cylinder randomly it’s undrivable.

David.

[DHallworth]

Yesterday afternoon the car was barely drivable and was struggling to make it up the hill to the farm in 2nd gear as it was running on 3 cylinders. When idling it was lumpy as hell and still on 3 cylinders.

Today, the injector I ordered was delivered just before 10am this morning. This afternoon I collected a Snap-On Apollo D9 from a friend of mine who very kindly leant me it to try and have a look at this thing.

I took it to fetch my wife from work this afternoon as I took her due to not trusting this car and there were no symptoms at all. I’ve been out driving it tonight for 2hrs and have done over 60 miles in it and it’s not exhibited any of the symptoms again.

Maybe the issue was the fuel filter and it was horrendous after it was changed due to an air lock? I’ll give it another day or two and see how we get on.

I really do hate intermittent faults

David.

[DHallworth]

Just a quick update on this...

I changed the fuel filter on this car in an attempt to cure the issue of it hiccuping or feeling like it was misfiring.

Despite the car having full Citroen (Arnold Clark unfortunately) service history, it was quite clear that at 70k miles the fuel filter had never been changed. It was horrid.

Changing the fuel filter seemed to make the car run worse the night it was changed to the point that it wasn't drivable. I borrowed a Snap On code reader from a friend the following day and drove it for around 50-60 miles with the machine connected so that I could monitor the injector flow correction values. Much to my surprise and annoyance the car didn't put a foot wrong!

Since this all started, the car has now done around 1500 miles with the new fuel filter installed and it's still running perfectly.

So... if you have problems, don't rely on main dealer service history and change your fuel filter!

David.