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[kevpuk]

OK, potted recent history....

Just had James over to do cambelt and service (great job too James ) when it transpired that one of the cam cover gaskets (passenger side  ) was poorly and oil in with the plugs. So, got a local guy to sort the gasket etc., and chuck in the new plugs from James.....and he noticed that one of the plugs was cross-threaded. Also commented that - not too surprisingly - (some of) the HT leads are a bit cr%p, no doubt due to hot oil etc.

Since all done, there is an occasional and slight 'stutter' under low rev acceleration really around the 1000rpm mark. No probs under more revs, that I have noticed, but definitey there at lower engine speeds.

So, I think the HT leads need replacing ? Kinda hoping not a spark plug issue - the crossthreaded 'hole' - as Helicoil probably not cheap ? Any thoughts/pointers ? What sort of task is lead replacement - can't see where they go, so guessing fiddly....? And, finally, any decent 'test' to diagnose plug or lead issue ?

[vauxfan2k]

I use an inline timing light to test spark strength, usually the light will flash quite brightly but if the lead is duff or the plug isnt earthing properly then it will gove off a poor light,

im sure others will have a more accurate way of testing.  

[kevpuk]

Ahh, yes, I remember such trickery Been some time since I have really had to do anything to cars myself......combination of laziness and having one car too new and one car too old for DIY  

Sounds like a good start point, thanks

[Ian_D]

OK, potted recent history....

Just had James over to do cambelt and service (great job too James ) when it transpired that one of the cam cover gaskets (passenger side  ) was poorly and oil in with the plugs. So, got a local guy to sort the gasket etc., and chuck in the new plugs from James.....and he noticed that one of the plugs was cross-threaded. Also commented that - not too surprisingly - (some of) the HT leads are a bit cr%p, no doubt due to hot oil etc.

Since all done, there is an occasional and slight 'stutter' under low rev acceleration really around the 1000rpm mark. No probs under more revs, that I have noticed, but definitey there at lower engine speeds.

So, I think the HT leads need replacing ? Kinda hoping not a spark plug issue - the crossthreaded 'hole' - as Helicoil probably not cheap ? Any thoughts/pointers ? What sort of task is lead replacement - can't see where they go, so guessing fiddly....? And, finally, any decent 'test' to diagnose plug or lead issue ?

That sounds EXACTLY the same as what mines doing.

Been meaning to change the leads since i got it (just over a year ago now  ) It will only miss if its sat ticking over at a roundabout for example, and then put your foot down quickish to set off! Missfire only lasts for a fraction of a second.

[kevpuk]

It will only miss if its sat ticking over at a roundabout for example, and then put your foot down quickish to set off! Missfire only lasts for a fraction of a second.

Bang on ! Welcome to an exclusive club  
Seriously, though, sounds like the leads are the fault......any ideas - anyone - on what sort of a job it is ? Meaning accessibility and so on, I realise the spark plug end is quite straightforward  

[Marks DTM Calib]

If it was the leads at fault I would expect the miss to occur when cruising, when accelerating from a constant speed or when accelerating hard.

Missing at idle sounds more plugs or an air leak

[kevpuk]

If it was the leads at fault I would expect the miss to occur when cruising, when accelerating from a constant speed or when accelerating hard.

Missing at idle sounds more plugs or an air leak

Hhmm, the plot thickens again Only started happening since the guy did the cam cover gasket and plugs.....could this be related to the cross-threaded plug and the new one not sitting nicely ?

[kevpuk]

Well it doesn't miss at idle, only when - generally only at low revs - you apply some throttle, then comes a quick, single, slight stutter.

I am thinking that this is when the load change is greatest,electrically, in that the electric juice required will spike then and if the leads are flaky then perhaps not enough hits the spark plug for it to make the leap cleanly ?

Any ideas on where to buy leads and how much ? Just called local Masterfit bods and they told me approx. £220 !!!!! Nuts !

[Marks DTM Calib]

Well it doesn't miss at idle, only when - generally only at low revs - you apply some throttle, then comes a quick, single, slight stutter.

I am thinking that this is when the load change is greatest,electrically, in that the electric juice required will spike then and if the leads are flaky then perhaps not enough hits the spark plug for it to make the leap cleanly ?

Any ideas on where to buy leads and how much ? Just called local Masterfit bods and they told me approx. £220 !!!!! Nuts !

www.autovaux.co.uk

[kevpuk]

www.autovaux.co.uk

Can't find them listed there, but have sent an enquiry....

How about these

[Ian_D]

If it was the leads at fault I would expect the miss to occur when cruising, when accelerating from a constant speed or when accelerating hard.

Missing at idle sounds more plugs or an air leak

Hhmm, the plot thickens again Only started happening since the guy did the cam cover gasket and plugs.....could this be related to the cross-threaded plug and the new one not sitting nicely ?

Im not saying it IS the leads... But my leads are shot anyway!

I opened the bonnet a couple of months ago to check the water level (it was late at night, so pitch black) and out of the corner of my eye noticed that all 3 of the HT leads on the drivers side bank were glowing blue