2003 C5 HDi engine miss/hunt

[SteveWrightNZ]

Greetings! First post!

I have purchased a second-hand 2003 C5 HDi that appears to be very very tidy in all respects.

However when at idle with the auto trans in park, the tacho will dip slightly every second or so, giving a little "hunt" or "miss".

This is also be heard when listening to the exhaust note, brrrrbumpbrrrrrrbumpbump etc.

Under gentle power-on driving conditions at low speed 40km/hr ish, it is also felt through the vehicle, and feels like auto-transmission surging.

Simultaneously, there is a whistle/peep sound from the engine compartment which is not noticeable at first, but once you know what you are listening for it can be heard while standing some 20 meters from the car.

It appears I should get the fault diagnosed professionally, but any suggestions in the meanwhile?


Best regards,
Steve

[Lighty]

Welcome along , difficult to diagnose the fault without hearing the car, sounds like it could be an injector.
The hdi unit is generally reliable once running.
Let us know what you find .

[SteveWrightNZ]

Hi there Lighty!

The sounds are pretty much as described. The whistle form the engine compartment is definitely in time with the engine fault. At times the fault will clear and the engine will idle smoothly for some 20 seconds before before it returns again,

I will use a short length of hose (from my ear) to listen around the engine compartment and isolate which device is making the sound.

The fault doesn't really ruin the character of the car, nor does it affect its' drivability or fuel economy - it just annoys me.