Flickering headlights and low RPM judder on 318IS

[MrT8064]

Now that winter has arrived and I'm actually having to use the headlights, i'm noticing that they are continually flickering slightly when i'm driving. Also when I'm not accelerating but cruising below 2,000rpm I get a bit of 'bunny hopping' or 'juddering', where the engine seems to surge repeatedly until I push the accelerator down a bit more and it will begin to accelerate normally.

Firstly I would like to know if anyone thinks these problems are linked (Also Fuse 17, power windows, is often blowing).

I know flickering lights can be down to a poor battery or alternator, i've voltage tested the battery while the engine is running and it measures 13.9-14V, but i'm not sure if I should be testing elsewhere too.

Thanks for any help!!

[Brianmoooore]

The juddering is usually a combination of minor air leaks on the inlet side and injectors in need of a rebuild (£10 each - see traders' section.)
Unless the flickering is simply a reflection of the juddering, the problem could be a duff diode in the alternator, resulting in it only giving a two phase output instead of three.
Fuse 17 should never blow, unless you habitually operate all the windows at the same time. Check for metallic debris having found its way inside a window switch.

[MrT8064]

Thanks for the reply. I had a look at some of the vacuum pipes, and surprise surprise one had a nasty little crack on it - I put a bit of tape over it and now the judder has very nearly gone. I think after I get a new hose installed it should be cured all together... Thanks!

As for the alternator, would this two phase instead of three be down to the voltage regulator or the whole alternator?

I'll have a good look at the window switches this week, I wonder if it could be a sun roof switching issue.

Thanks again

[Brianmoooore]

Thanks for the reply. I had a look at some of the vacuum pipes, and surprise surprise one had a nasty little crack on it - I put a bit of tape over it and now the judder has very nearly gone. I think after I get a new hose installed it should be cured all together... Thanks!

Unless they are known to be less than 50k miles old, get the injectors rebuilt anyway. It will be the best MPG/BHP return for your £ that you will ever get.

As for the alternator, would this two phase instead of three be down to the voltage regulator or the whole alternator?

Unfortunately not. The diodes are not part of the regulator pack.
They can be replaced with the aid of a heavy duty soldering iron, but it's more cost effective to fit a second hand alternator.

I'll have a good look at the window switches this week, I wonder if it could be a sun roof switching issue.

Unless you habitually park your car on its roof, there won't be anything that's slipped inside the sunroof switch. The windows switches are ideally placed to collect bits of metallic rubbish, such as the odd pin or piece of aluminium foil.

[MrT8064]

Getting the injectors cleaned does sound like a good idea - i'll have a look at the price of new ones though first... guessing they'll be a lot more than a tenner!

I ordered a second hand alternator today off ebay for £17. I'll update once its fitted re the lighting issue.

I'm going to have a crack at fixing the windows over the weekend, and will update.

Thanks so much for the replies

[MrT8064]

Just to update:

I fitted the 'new' alternator yesterday - (really easy job. i'm still a bit new to tinkering and this only took me an hour). The flickering lights no longer flicker, also the car seems to run a little better especially when driving gently. Very happy!! I had thought the only sign of a bad alternator was it's inability to charge (which it still did fine!).

Re: the windows causing fuse 17 to blow. I took both window switches out and couldn't see anything wrong, however one of them 'clicked' fractionally more then the other when pressing either button. at the moment i'm just using the non 'clicking' one for the drivers side and nothing for the passenger one - a week down the road and fuse 17 hasn't blown... i'm going to give it another week or two before saying it's definitely a bad passenger switch!