Hoping someone can help with this annoying issue.

Recently, and more obviously when cold, I have been getting a jerky/juddering sensation in the car when idle.

On startup, the revs sit for a second or so just under 1000, then drop a bit and then the juddering starts. The jumpyness goes when you give it a bit of right foot, say up to 1200-1500.

It seems that often this will disappear after the car has warmed up/by the end of a journey, but sometimes it continues this throughout a journey and you notice it when sat at lights, junctions etc.

There has also been a whining noise when accelerating though the low gears for the past few weeks. From reading around this could perhaps be the alternator or belt tensioner pulley.

At night when idling the interior lights and headlights, as well as the backlights of the stereo, buttons etc will flicker.

It had a new injector a few months ago which significantly reduced the rough idle from the compression loss etc. and a Terraclean 2 weeks ago.

The whine sounds similar to this

which turned out to be the alternator; if it is on mine, could that contribute to the 'dodgy' idle?

Issue solved

How ?

Please share the fix for future reference for others :)

Good Morning,

I have this exact issue please can you share how you fixed it?

Thanks in advance.

So having driven the car solidly for the past year (18,000 miles-ish) I find it all too easy to pick up on even the smallest of changes in the way the car drives or what it sounds like.

For a little while I had noticed that the engine would idle rough when first started in the morning but would usually sort itself out when part way through or after a journey. However more recently I noticed occasions where the roughness would continue throughout a journey and the whole car would judder when stationary at lights, junctions etc.

I happened to notice this at night and as a consequence of the changing engine speeds all the lights were flickering, interior, stereo/dash and headlights. Hence though it might be electrical related.

My thoughts:

1) Is the alternator dying and not charging the battery properly, and intermittently loading the engine? Perhaps a bearing was shot. Had also noticed that it takes longer to start after leaving it longer after driving.

2) Is the battery on the way out or is there something wrong with the smart charging system? Perhaps the battery is dying and not charging properly and the voltage fluctuations are related to this.

3) It might be something to do with the engine itself? Hopefully not another injector/seal that need replacing leading to compression loss thus unbalanced forces on the crankshaft throughout the firing sequence

4) Also for about a month there has been a whining noise coming from the engine that you hear mostly on acceleration from about 1000-2000 rpm before other things become louder. Reading around this could be the alternator, a pulley or something else on the same belt.

Convinced it was something electrical, I got a multimeter out. Everything off, I tested the battery - 12.3V. Ok I thought, perhaps a smidge low.* Turned the ignition on - (can't remember)V - but was ok. Turned on the engine - idle was rough and jerky, and you could see the engine itself jumping back and forth a couple of times every few seconds. Car was juddering. You could see this in the reading on the multimeter, the voltage across the battery was fluctuating up and down in a sinusoidal-like manner.

Turned off the engine, restarted. Idle was still the same. Now the interesting bit. Before I had an injector replaced a few months previously, I remember noticing that the priming bulb was pretty solid - full of fuel. More recently it still had some squeeze to it ie. there was some air in the system. This probably wasn't helped by me having disconnected the fuel filter a couple of times attempting to blank the EGRV - though I seemingly primed it properly after each try. So I pumped it a few times until the squelching noise stopped. Started the engine - it started more quickly than before and the idle was smooth. No jerkyness. The reading on the multimeter was stable also at about 14.4V indicating that the alternator was charging the battery, and the reading was also within the range of the voltage regulator on the alternator (14.2 - 14.7V).

Decided to stress it a bit turning on headlights, heated screens, stereo, air con (much more than I would have on usually at any one time) and the voltage increased slightly to 14.5-6V but remained stable. Called it a day as the issue was seemingly fixed.

The next morning I started the car again but the jerky idle had returned. Turned off engine, again pumped the priming bulb and restarted. Jerkyness gone, idle was smooth.

The day after that I did the same, but it took two restarts and pumps to get it to idle smoothly. The second pumping I decided to be more thorough, so I pumped it 30 times, then paused (hands starting to ache as well), pumped a further 30 times, then squeezed and held for 10 seconds, released, and squeezed and held for 10 seconds again. Car ran well.

Since then it's been fine! (fingers crossed, touch wood etc. :P )

I still have the whining noise though - haven't got this checked out yet.

Conclusion - air in fuel was causing rough running and resulting in the fluctuating engine speed which lead to (nerd alert) a changing rate of intersection of magnetic field lines with the copper windings in the alternator per unit time hence the fluctuating voltages. Further reading around leads me to find out that the first version of the low-pressure fuel pipes on this engine were prone to wear from rubbing and vibrations leading to pin-holes that can lead to the slow ingress of air; fixable with the priming bulb were required, but quite inconvenient. Permanent cure would be to replace with a new a new fuel pipe assembly (1501910).

I think that's everything!

*As far as I know the car has been on the same battery in the 7 years-ish that it's been in the family and just had it's fluids topped up where required, hence the though that perhaps the battery is dying.