HT Leads?

[JeffW]

Hi all

Less than a year ago I had a misfire at around 2800rpm, which I found after much assistance here to be either the coil or the leads. I replaced the coil first, which improved it, but the misfire was still present. When I replaced the leads, the misfire disappeared. I checked and had two wires with very high resistance. These original leads were about a year old when the misfire developed and installed by Faversham (green silicone versions). I replaced them with a new set of green silicone ones.

However the problem has now returned. I checked the resistance and found one has very high resistance compared to the others.

Are these green silicon leads particularly delicate? The only time I took them off in the last 8 months or so was to do a compression test.

I am wondering if my tidiness in using the cylinder head clips is damaging the internal wiring?

Any thoughts?

Thanks

Jeff

[dasadrew]

Interesting .... I too still have an annoying sporadic mini-misfire. It doesn't really seem that one cylinder is missing, but rather that it's not firing properly. In the course of changing all the different components, checking the timing, meticulously setting up the carbs etc., someone (can't for the life of me remember who) said to ditch the "replica" green cables as they are known to be poor. I bought a set of those sooper dooper thick blue ones which that chap on eBay makes up. They're a bit annoying because they are a very tight fit in the clips. Went out on a run - everything ok. A week later that annoying little semi-misfire is back every so often. It seems like there is something which benefits from being touched evey so often but which then creeps back into a state where the spark slightly breaks down.

I'm doing the diff at the mo, but when it's running again I've got a new coil to fit and different spark plugs.

Interested in seeing what others say about the Green Leads as they finally didn't seem to be my problem.

Drew

[022Dave]

Have you also checked the dizzy cap & rotor arm for cracks and current tracking? For info, I've had a set of Magnecor leads fitted for the past 15 years without problems. Not cheap, but they have proved worth the price.

Dave

[singapore stag]

When taking off leads or doing other work in relation to leads always pull them off from the spark plugs as close as possible to the plug by the sheath with both hands. If not pulled off carefully you are liable to streach them and do other internal damage not noticable to the naked eye ( not teaching to suck eggs etc ). I have damaged brand new 10mm leads by not following this procedure.

Sukh.

[singapore stag]

These black clips spacers for 10mm leads are good.

[Bandit1200]

Thanks Jeff for starting this thread. I have been annoyed by what I can only describe as half a cylinder misfire and will investigate leads.
Steve

[JeffW]

Thanks for all the responses - it is a frustrating problem.

dasadrew - have you tried the cold coil swap test? I read about it here to diagnose misfire to eliminate coil being the source as apparently some coils misbehave when hot. Which plugs are you using? I swapped to NGK's and had nothing but problems so went back to Bosch WR8 DC+ and my engine loved them. I realise this is a contentious issue as some swear by NGK!

022Dave - new cap and rotor already installed, but thanks for the tip. I think next step for me is shelling out for the Magnecors - big price difference but hopefully worth it.

singapore stag - thanks Suhk. I have been trying to be extra careful with them, but perhaps I stretched one!

Bandit1200 & dasadrew - mine is almost a buzzing sound when it misfires and a noticeable loss of power. It is very specific in terms of RPM as well - it does not do it across the band. Hopefully yours can be solved by some of the tips here too.

I already have a new set of green ones waiting at the post office so will give them one more try before swapping to Magnecors.

Thanks

Jeff

[Klaus Schlueter]

In 2000 I had misfiring on my Stag and I bought a set of BERU leads. No problem since. In my files I found an old cable list with the BERU types, lengths and connector type.
I made a note that the resistance is 5,6 kOhm/m and good for 40.000 V.
These cables seem to be still available.

https://www.beruparts.de/find-my-par...g/r400.pd.html
https://www.pkwteile.de/ersatzteile-...ndNo%5B0%5D=11

Klaus

[dasadrew]

JeffW I started with some Hi-Tech Beru plugs with 4 prongs - looked like the Predator's teeth! Not good. Switched to NGK. Now got some Champignons ready to try out. Have also got a "genuine" original Rover Dizzie Cap (bl00dy expensive) to try, and a Bosch Red Coil. VOR at the mo due to diff overhaul, but I want to do the changes one-by-one.

I had original Lucas points fitted and meticulously set up. However, I switched to LD Parts elctronic ignition and WOW! - what a difference! I really couldn't believe the change - brilliant!

I know Klaus has the Beru leads (wasn't Aunt Beru in Star Wars?) but I've still hesitated as I quite like the angled original plugs.

Drew

[JeffW]

In 2000 I had misfiring on my Stag and I bought a set of BERU leads. No problem since. In my files I found an old cable list with the BERU types, lengths and connector type.
I made a note that the resistance is 5,6 kOhm/m and good for 40.000 V.
These cables seem to be still available.

https://www.beruparts.de/find-my-par...g/r400.pd.html
https://www.pkwteile.de/ersatzteile-...ndNo%5B0%5D=11

Klaus

Thanks Klaus - interesting and very nice leads. I also note with some surprise the rated resistance - the wires I have just removed average around 10-12 kOhm (excluding the short ones). The one that is suspect is 20.

[JeffW]

JeffW I started with some Hi-Tech Beru plugs with 4 prongs - looked like the Predator's teeth! Not good. Switched to NGK. Now got some Champignons ready to try out. Have also got a "genuine" original Rover Dizzie Cap (bl00dy expensive) to try, and a Bosch Red Coil. VOR at the mo due to diff overhaul, but I want to do the changes one-by-one.

I had original Lucas points fitted and meticulously set up. However, I switched to LD Parts elctronic ignition and WOW! - what a difference! I really couldn't believe the change - brilliant!

I know Klaus has the Beru leads (wasn't Aunt Beru in Star Wars?) but I've still hesitated as I quite like the angled original plugs.

Drew

I replaced my (likely original) Lucas coil with the Bosch Red so perhaps you can rule that out now, unless you got a bum coil from the junk dealer on Tatooine.

I have an older Luminition and from what I have read, most people say they either work or they don't, so I don't think my misfire is attributable to it.

Let us know how your mushrooms work!

Jeff

[Klaus Schlueter]

Drew, I think we all have our own "plug story". I started with Champion in 1993-not so good. Changed to Bosch W8DC for many years but had some malfunctions over the years-so changed to NGK BP5E. Running fine now.
Klaus

[dasadrew]

Drew, I think we all have our own "plug story". I started with Champion in 1993-not so good. Changed to Bosch W8DC for many years but had some malfunctions over the years-so changed to NGK BP5E. Running fine now.
Klaus

Spark plugs can be weird things; in my RS2000 I use orignal Ford Motorcraft spark plugs. Last summer, after taking the car out of winter storage, it had a misfire. Searched for all of the usual suspects - moisture, rodent bite on HT leads, plug lead loose, dirt in carb jets and the rest. Turned out a single spark plug had completely given up the ghost during winter in a closed garage. How on earth can that happen?

Drew

[Goldstar]

Jeff have you checked the lumention splitter/chopper for cuts/nicks/splits or positioning. That may give you an intermittent problem. I also clean the eye once in a while with a micro fibre cloth. Lastly the plastic plug can get grungy so might need a clean or at worst replacement. Some have used marine type plugs for theirs. I changed to pertronix and a flamethrower coil which runs well but not cheap (I imported mine from the auS via eBay and saved £50). Good luck finding the culprit

[JeffW]

Jeff have you checked the lumention splitter/chopper for cuts/nicks/splits or positioning. That may give you an intermittent problem. I also clean the eye once in a while with a micro fibre cloth. Lastly the plastic plug can get grungy so might need a clean or at worst replacement. Some have used marine type plugs for theirs. I changed to pertronix and a flamethrower coil which runs well but not cheap (I imported mine from the auS via eBay and saved £50). Good luck finding the culprit

Hi

Yes, chopper replaced as when Faverhsam was trying to figure out carb problem we swapped dizzys to see if I had a problem with it. They swapped choppers just to eliminate it. Eye was cleaned at the same time.

What is the 'plastic plug' you refer to?