Running Fine but after 161,000 mile HT coils replaced !!

[iangray100]

I thought I would post this to see if anyone else has experiance this .

I decided my car deserved a treat after having travelled 161,000 miles ( 40,000mile since I rebuilt the engine ) and the car has been in my ownership now for over 7 yrs + 55,000 miles.

The car ran fine but one day while driving I was trying to work out how many sparks the original HT coils must have done .....my maths gave up....!!.

So I order two coils off EURO Carparts ( cheapest place to get 2x 964 coils with free P&P ) and I fitted them on Sunday.

On the old coils there were no noticalable cracks or issues in the cables or its installation but I did fit a couple of "internal hairy" retaining washes to the Low tension connectors so we had a 100% good electrical connection and also made sure we had a good earth, on the lead behind the coils to the cars chassis.

After the installation I went out for a quck test drive and "Wow" what a difference to the pick up of the engine ..much smoother and quicker.

So the moral of the story ....while driving,perhaps think about how many sparks your coils have carried out in there life and then feel sorry for them .......

 

[Steve Brookes]

I saw an improvement in response when I changed the dizzy caps (the ones on were really badly pitted) but I believe I'm still on the original coils so think I'll change mine too. Thanks for the tip Ian. []

 

[iangray100]

Current update .... Went out just now to work and I have no cold hesitation ....sometimes in the morning the initial "cold" tickover can be a little lumpy, its now as smooth as silk and very noticeable a lot quicker in throttle response when driving ....best performance improvement for approx £110 I have carried out for a very long time ;-) I suspect the coils were dieing ...

 

[C2dweller]

I'm about to press the buy-button on a new set of ignition leads, but might try this first. (I did another mist-spray test on the dizzy caps last night and was astonished by the arcing I saw. One of the best arcs was across to the jubilee clip on the heater ducting [8|])

 

[iangray100]

If you have HT arcing on the distributor then replacing the coils won't help... It could make the arcing worse .... As you will have a more powerful spark . I replaced all my leads and distributors last year so all this was A1 before I did the coils last weekend.

 

[C2dweller]

My initial hypothesis was: a coil fault was creating a super voltage at the dizzy and causing the arcing - plucking at straws to avoid the new leads I'm afraid. A quick test shows normal winding impedence [] Not wishing to wonder off topic too much but what made you change your leads? any symptoms or just general maintenance? My problem is poor light throttle performance - say edging along in traffic and labouring the engine - causing kangaroo moments. Under full / part throttle its fine. I put this down to a weak spark that fails to ignite the low fuel/air mixtures. My last test was to try and improve the engine earthing - hypothesis being poor ground and spark not wanting to jump gap at the cylinder end and prefering to arc across at the distributor ... cut short by my Wife complaining about the noise when the kids were asleep [] ... like I say I'm trying to avoid buying new leads when there could be another fault Cheers, Lee

 

[iangray100]

I replaced leads and distrutors as I had arcing on the leads seen at night . Leads are a consumable item , they do not last for ever ... Measured by years or miles. Just because they are not a moving mechanical item they to break down due to ageing. Current will find the shortest route to earth ... Ideally via a spark plug not via the cable insulation !! I would always go for leads before a coil .

 

[C2dweller]

I was doubtful because all leads seem to arc - not just the odd one.

 

[iangray100]

Personally I wouldn't be surprised , as they are all aging at the same time and work in the same hostile environment .

 

[AVI_8]

C2dweller, As a temporary fix to your arcing leads problem, give them a good spray with WD40 and rub the WD40 into the leads with a cloth, a couple of coats. I did this on an Imprezza a few years ago and it stopped the arcing for several months. The only problem is that on a 964 you would have to take off a lot of surrounding components in order to get to the leads to do this, but try it on the visible areas and see if it makes any difference.

 

[C2dweller]

Cheers both - I finished my little test tonight where I earth strapped from the valve cover to a few different points on the bodywork - made no difference. Arcing was on a grand scale - worse than ever seen [] Sprayed with WD40 to remove the danger! Over winter I removed both dizzy caps and plastic covers to give them a good clean and coat with WD40. Its all new stuff, so mainly just removing any coatings applied during manufacture. I also removed most the leads and cleaned them in the same way in the Autumn. I would just like to understand why they fail... The copper lead is really reliable, which leaves the damping resistor at the spark plug end and the dizzy contact at the dizzy end.

 

[iangray100]

A quick Google found this : According to the AA, a problem with the High Tension (HT) leads is a common cause of car breakdown. The HT leads and their connections do deteriorate gradually with age. Moisture and dirt can enter small cracks in the insulation, increasing resistance within the wiring and so reducing the ignition voltage. Read more: [link=http://www.car-insurance-uk-supermarket.co.uk/blog/ht-leads.shtml#ixzz1GhkhDk2G]Common car breakdown cause: HT Leads[/link] From the UK's comparison site for [link=http://tcr132.tynt.com/ads/98/1GhkhDk2G]Car Insurance[/link]

 

[C2dweller]

Picking up a new set of leads tomorrow []

 

[C2dweller]

New leads, as feared, didn't make a great deal of difference [] I did poke about and found a very slack breather pipe from the rear of the ISV back to the oil tank (I presume). Tightened this, and cleaned the air flow sensor - this time focussing on the white plastic protrusion. All this made things great [] I think I'm done - I can enjoy the nice weather now.