how do you know when spark plugs need changing?

[Will.]

for a few weeks now my car seems to be a bit jumpy when acceleratingfrom low revs in low gears ( if i slow right down and im in 2nd it judders until i get past 2k, and does it with 3rd sometimes aswell). spoken to a few people and some have suggested bad batch of petrol (i have had 3 lots of petrol since it started so it cant be this). others say it might be a fialed spark plug. how do i know if this is the case?

 

[Budgie]

Take them out, one at a time, and plug them into the HT leads. Keep your hands well away and turn the key. Should be a blue spark. You'll notice if one is different to the others.

 

[Will.]

whats the HT leads?

 

[Budgie]

The leads that go onto the end of the spark plug.

 

[Will.]

ahh right. thankyou

 

[c__w]

If they plugs have done some mileage (50,000+ or less if you're picky) just change them as a matter of course. The test described above isn't very accurate to determine their condition, it's a good test to check that cylinder's/HT cable for a working spark/ignition circuit though. The plug may spark fine in the open but under compression inside the engine it might be weak but you'd never tell by "testing" it IMO.

 

[gtruk]

I have the same problem, im going to have a good luck at it the weekend. Has your car been remapped?

See my thread. My car is on 65k

http://www.cliosport.net/forum/showthread.php?t=395953&highlight=spark+plugs

 

[leecup]

for the sake of a few quid get some new spark plugs but do not goto renault for them unless your a rich man! 22 notes each i believe

 

[st3ve]

Basically when you take them out if they have surface rust like mine did you know it's time for a new set otherwise it's entirely up to you but considering the cost of them it's worth doing to eliminate the spark plugs being the cause.