Engine hunting on idle Citroen Berlingo b9 1.6 hdi 90

[Ala2dyn]

Hello everyone,

I have a 2011 Citroën Berlingo 1.6 HDi (DV6 engine) with an annoying idle problem. The engine sometimes hunts at idle — the RPM dips like it’s going to stall, then recovers by itself.

It only happens at idle (never while accelerating).

If I switch on the A/C the engine rpm rises a bit and the hunting stops

Sometimes it stabilises on its own after a while, but other times it keeps hunting until I restart the engine.

When I shut the engine off, about 3 seconds later I hear around 6 “zip” noises from the throttle flap area (is that normal?).


What’s been checked/replaced so far:

Fuel pressure regulator replaced.

Throttle flap (air doser) checked → looks clean and moves well.

MAF (débitmètre) cleaned → no change.

Timing belt inspected → no tooth skipped.


Live data during hunting:

Idle RPM: ~684 to 760

Fuel rail pressure swings between 26,000–38,000 kPa

MAF around 5–6 g/s (sometimes lower when it hunts)

[mickthemaverick]

That swing in fuel pressure strikes me as odd. With the engine at idle I'd expect a much lower swing so I'd be looking at the injectors to see if one is not performing correctly and causing erratic fluctuations in the fuel rail pressure.

[shtu]

What Mick said.

Look at the live data for the njector correction values and see if anything looks odd there, eg, wildly different or fluctuatnig values on one injector.

[Ala2dyn]

I tried to unplug the egr today, i felt the car a bit more powerful, i did measure the injectors they were a bit weak but equal in fuel delivery, i shared this picture for live data i got while engine was hunting, this problem is getting me crazy i tried almost everything