Car problems - Not firing on all cylinders

[Stu]

My Volvo is not firing on all cylinders. This is an intermittent problem.
Called the garage, they said they couldn't see me today, but to book it in in the week.
Don't expect to be able to fix it myself - but can I drive it a mile from my house and call the AA?
If not, is it harmful to drive as is? - will all that unburnt petrol ruin my Catalyst?

Many thanks
Stu

Originally Posted by Stu

My Volvo is not firing on all cylinders. This is an intermittent problem.
Called the garage, they said they couldn't see me today, but to book it in in the week.
Don't expect to be able to fix it myself - but can I drive it a mile from my house and call the AA?
If not, is it harmful to drive as is? - will all that unburnt petrol ruin my Catalyst?

Many thanks
Stu

My galaxy was recently driven for around 5 miles with the engine not mounted in properly (women!)

I'd liken it to the SV on one pot. Shouldn't do much damage if any at all. But don't take my word for it :P

i had this on an astra cdi the once and it was the HT leads breaking down.

[Biker Biggles]

Have you checked the plugs and HT leads?One tip for finding an electrical misfire is to find somewhere very dark and run the engine.Look under the bonnet and you may see arcing where the fault is.

you can narrow down the problem by feeling the plugs to see which one is not running hot and hence misfiring, and following the above instructions to recitify. But let's be honest about this, if you have a Volvo worth saving your either very wealthy, in which case no advice here is going to take the place of a dealer, or you've a blue rinse rinse in which case you shouldn't be on the road?
OMG STU HAS A VOLVO!

Had this problem recently on my Astra.

Thankfully Dad's a mechanic & this is what he did when i asked him to take a look at it...

With the engine running, take the lead off each spark plug in turn & hold it near the engine block or another suitable metal point - if it arcs to that point then you know the lead is ok. If all are ok then it may just need a new set of spark plugs.

N.B. Disclaimer: obviously don't hold the leads in such a way that they could arc to yourself - I accept no responsibility if you get a shock!

Sadly in my case it turned out the head gasket had failed. Check for any sign of 'hydraulic-ing' (My Dad's word, not mine ) (engine not turning over & sounding like it's stuck) which could indicate water in a cylinder. You can also check the oil filler cap to see if there's any sign of emulsification (water in the oil). Mine was also making a lot of white smoke from the exhaust even when the engine was warm.

Here's hoping it's just a new set of plugs you need - about £15 as opposed to £300 for a new head gasket!

HTH

[Stu]

Just had the car serviced. So unfortunately I assume all the spark plugs were replaced so won't be that.
A while ago I did see mayo on the dipstick but didn't do anything about it because there was none under the oil filler cap.
The thing is it's not running bad all the time so difficult to carry out all these checks when most of the time it's fine.

But appreciate all the help! Thanks

[Spiderman]

Like other above have said i'd be wary of a faulty HT lead. Too ages for mine to show itself as being that.
When i'd finaly decided that was the culprit (borrowed some HT leads of a mates car) and pulled it out i decided to do a bit of surgery on it beforte binning it. So i sliced its rubber sheath along its length and about 80% of the lead was rusty I never understood how the water had got into that one so badly compared to the others.

A servise wont have picked up on a faulty HT lead btw mate so well worth a fiddle with those.

I had this issue with my Astra too (must be 5hitty Astras huh )

I just removed each HT lead in turn and sprayed 5hit loads of WD40 down each plug-cap and it was fine again

[timwilky]

Had a terrible intermittent misfire on the daughters volkwagon. When we eventually fell out with the local STEALER I persuaded her to let me service it myself. I found out the reason why. They had not fitted the little cap properly onto a spark plug and it had come off pushing the ht cap off the plug. Go over a bump in the road and you got a misfire. B'stards I suspect they did it deliberately as I had complained about them advising that the discs need changing and they had only changed them at the previous service.

Or more likely they were just bloody incompetent