Another vote for Autolink leads
mine are 7mm burgundy silicone
fitted for 4 years with no trouble
Hi Guys,
Sorry to reopen an old thread but does anyone have any advice on testing the VVT leads please since the coil pack pushes onto one spark plug directly then 2 different lengths of leads.
A couple of quick questions:-
- does the coil pack plug > sparkplug wear out or is it normally the HT leads from the Coil pack to the sparkplugs?
- What would the resistances range need to be in for a âworking leadâ
- Is there a way to test if the coil pack is the issue (or is this unlikely/wouldnât work at all)
The issue iâm having is the very occasional cylinder misfire (seems to be only days when itâs been wet for a few days) and will only do it once during a drive and then be absolutely fine, and it wonât so it every drive in the wet or damp, to me it sounds like some moisture might be seaping in overtime round the HT Lead seal > spark plug and then as its driving the dries out but canât back that up with evidence :-/
A very simple test of condition of ignition systems is to wait until a dark night and run the engine with the bonnet open.
Look carefully at all the leads, plugs and coils: if you can see any blue sparks trickling away, then there is a definite problem.
However, no sparks visible on the outside doesnât necessarily mean theyâre not shorting somewhere on the inside.
The most common problem Iâve come across over the years is a plug going high resistance, making it difficult for the spark which then looks for an easier path, such as punching through the lead or tracking down the plug or the outside of the coil - visible.
Plug problems usually happen in the first few weeks after a routine plug change, but only if there is a hint of weakness in the plug, otherwise they soldier on for years. Which is why I always keep the old plugs for a while.
If it is a damp problem, water ON the electrics, then this is what WD40 was designed for (Water Dispersant version 40). With their distributor and leads directly exposed to the elements, the old original Minis only survived because of it!
WD40 is a surprisingly good insulator, so beware this makes it totally useless as a contact cleaner and thus no good for water IN the electrics.
Probably not the most reliable test but the resistance of the secondary side of the ignition coils (measured from where the spark plug connects and the HT lead connects should be 7 - 11 K-ohms at 20*C. HT leads should be 16 K-ohm per meter.
Thanks Guys will have a look at both these ideas on SaturdayâŚI know that WD40 is water dispersant, but where are you saying to put it? Round the rubber of the HT lead (away from the contacts)
OK, so I ordered a new set of Leads from MX5 Parts (5mm Ignition Leads, Thundercore Pro), Tested the resistance on these before I fitted to compare with the old leads and the results are below if anyone needs them:-
long new 0.900 (2k)
long old 8.74 (20k)
short new 0.294 (2k)
short old 3.16 (20K)
Well thatâs frustrating, so have replaced the HT Leads and Spark plugs still having a single misfire p0300 code a day (not per drive). The Coils appear to be OK and are the 2nd set Iâve had on there with the same issue. Iâm unsure what to try next short of getting a garage involved :-/ but think they will struggle since it seemingly happens at random at low revs, when the weather is damp and only once a day.
Did you try Richardâs suggestion of looking at the leads etc on a dark night
yeah no sparks anywhereâŚunder the bonnet and the leads are brand new.
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