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mgf
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Discussion Starter · #1 ·
Hi folks. As the title says, just looking for a bit of advice before replacing my existing leads and plugs in the hope of curing an ongoing erratic idle/misfire issue when starting from cold. As a background, I’ve changed the IACV for a brand new OEM one, performance panel filter, regularly use Redex in every tank, etc - no probs once she’s warmed up for a few minutes but the initial few mins are me with revs hunting up and down between almost zero and 2000. A few blips on the throttle seem to sort this out but doing that also results in several loud misfire noises from the exhaust.

Anyway, I am digressing.

Looking at leads themselves, I am eyeing up some Magnecor leads but am not sure which ones to get or which would be best suited. My car is a very late 2001 MGF 1.6 MY2000 MEMS3 - it’s my understanding that I should be looking for a set of x2 leads, not the other kits. Right??

If so, I am considering Magnecor 8.0mm Blue leads MPN 40393. Also looking at the slightly larger diameter Red KV85 leads 8.5mm MPN 45393m I think.

There is only a few quid between the two, the Red are supposedly race leads - overkill?? - and ‘should’ fit into the original holders by all accounts I’ve read.

So, I’d really welcome your thoughts before I proceed. Oh, the plugs I’ve bought are Denso Iridium Twin Tipped ones, if that makes any difference.

Thanks in advance
Steve
 

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rover_75
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Hi folks. As the title says, just looking for a bit of advice before replacing my existing leads and plugs in the hope of curing an ongoing erratic idle/misfire issue when starting from cold. As a background, I’ve changed the IACV for a brand new OEM one, performance panel filter, regularly use Redex in every tank, etc - no probs once she’s warmed up for a few minutes but the initial few mins are me with revs hunting up and down between almost zero and 2000. A few blips on the throttle seem to sort this out but doing that also results in several loud misfire noises from the exhaust.



Anyway, I am digressing.



Looking at leads themselves, I am eyeing up some Magnecor leads but am not sure which ones to get or which would be best suited. My car is a very late 2001 MGF 1.6 MY2000 MEMS3 - it’s my understanding that I should be looking for a set of x2 leads, not the other kits. Right??



If so, I am considering Magnecor 8.0mm Blue leads MPN 40393. Also looking at the slightly larger diameter Red KV85 leads 8.5mm MPN 45393m I think.



There is only a few quid between the two, the Red are supposedly race leads - overkill?? - and ‘should’ fit into the original holders by all accounts I’ve read.



So, I’d really welcome your thoughts before I proceed. Oh, the plugs I’ve bought are Denso Iridium Twin Tipped ones, if that makes any difference.



Thanks in advance

Steve


Just what I was going to ask


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mg_tf
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Quick question about HT leads before I buy....

Hello Steve,
Not sure why you would suspect HT leads to be electrically substandard when cold (and it certainly isn't cold now) yet OK when hot - which is is at the moment.

Possibility - and it's only a possible to confirm or otherwise:- cold start sensor, which senses the coolant temperature and signals the ECU to provide the correct mixture in relation to temperature. As I understand it, if these fail, they do so to a default resistance value at a sort of half way house, so instead of having a correctly rich mixture when cold, it gets a somewhat weaker than necessary mixture and the car doesn't like it until it warms up a bit. Just w thought.

Another thought (if your really want to go down the HT leas route) would be to buy (even borrow) a cheap set from another car to try.
Kind regards,
Austin.
 

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Possibility - and it's only a possible to confirm or otherwise:- cold start sensor, which senses the coolant temperature and signals the ECU to provide the correct mixture in relation to temperature.
On a point of detail, there is no cold start sensor on an F or TF - just the coolant temperature sensor that 'signals' the ECU.

Apologies for jumping in, but I just thought it was worth clarifying in case the OP started looking for one.
 

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Quick question about HT leads before I buy....

Thanks Ian.
Same function - different description. i.e. It's the sensor that senses the coolant temperature and signals the ECU to set the correct mixture in relation to the coolant temperature st that time. Hoepfully, it was clear that that was what I was referring to for the 'whatever-one-calls-it!
Kind regards,
Austin.
 

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mgf
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Discussion Starter · #7 ·
Thanks for the replies, fella’s. Actually, forgot to mention that I have indeed already changed the coolant temp sensor (and not the one that feeds the dashboard dial!) so presumably that has been ruled out as a potential cause of my cold start misfire/rev problems. I changed that whilst I was doing the IACV not too long ago.

As for the leads and why I am considering changing those is that I have read that the original OEM ones are pretty crap. I don’t know if they’ve ever been changed, and as such I’ve thought that they ‘might’ be damaged and perhaps have a degree of moisture ingress that could be causing the problems on cold start. Maybe after warming up a bit, that moisture has evaporated because as mentioned, she’s fine after what I call ‘burping’ her for a few minutes after the first start up of the day. She coughs and splutters and misfires a handful of times until the revs even out and remain constant at their normal 850 mark.

I can’t really be bothered trying to test a different set of leads, mainly because I don’t have any nor know anyone who does!!

So, it seems like a logical step to change the plugs and also the leads. I don’t know what else it could be as I’m practically changing every bit of the car to diagnose!!!

Back to the lead question. If anyone has any experience of the Magnecor leads mentioned and their usage in our little cars, that would be great. Anyone used either the Blue or Red leads on their car? - any advice on which to go for? - price is only a couple of quid difference but I want to get the best ones possible instead of faffing about even more.

Thanks again.
 

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rover_75
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I’m considering changing mine as part of a service.. The poor thing literally had no service history.. I maybe answering my own question but is there any gain in upgrading then leads, in a TF the seem pretty short so losses and break down should be minimal compared to the old days, and it’s harder to show of the Bonny colours lol




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mgf
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Discussion Starter · #9 ·
Well, being impatient as I am, I drove down to Demon Tweeks and bought a set of Competition Red KV85 8.5mm Magnecor leads. £36.00 vs. £32.00 for the 8.0mm Blule ones. The chap said that they would fit, so now just to find some time to get them installed and see if it makes a difference.......

 

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You might have two coils, but you still have four spark plugs...
 

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mg_tf
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x2 Coil packs. My car has 'em. No Dizzy. Only need two leads as one fires 1 & 3, the other 2 & 4 cylinders.

I thought they looked like deep recessed spark plug leads!! So those black plugs go to the coils and then off each coil there will be 2 spark plug leads? So 6 leads in total if you were going to replace the lot?


I'll have to take the cover off mine to have a look...
 

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mgf
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Discussion Starter · #15 · (Edited)

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mgf
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Discussion Starter · #16 ·
Right, haven’t had time to do anything in relation to changing these things.......

Maybe a dumb question, but both leads in the Magnecor set are the same length but numbered 2 and 4. Looking from the rear of the car with the cambelt on the right side, which lead goes to which plug? - I’m not sure of the firing order nor which one goes where.......

Help please before I start, hopefully this weekend!
 

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HT Leads and coil packs

Yes one coil pack serves two sparkplugs. The coilpack has its own plug connection sticking from under it, and a plug lead to connect to the adjacent sparkplug on the next cylinder. Only two leads required.


I keep a spare secondhand coilpack in my spares box, that I managed to blag from our sponsor. Well two actually, but one was fitted and it seemed to help keep the occasional misfire at bay, so it stayed on.


I will probably treat my car to a couple of new coil packs and leads soon. I thought the original OEM ones were meant to be good quality....most cars still have originals on after 14 years or more!


Sundance
 

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mgf
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Discussion Starter · #18 ·
Yes, I’m aware of the setup and coil packs and only 2 leads required. My dilemma is once each lead is connected to each coil pack, which plug do each end of the leads get connected to?

As both Magnecor leads appear to be the same length, so could go to either of the “free” plugs, they are numbered 2 & 4, therefore are somewhat specific to which cylinder the are used on - for firing order, I guess.

This is why I need to know the numbering or order of the cylinders to ensure the leads go to the correct plugs.

Oh, I also bought new OEM coil packs....might as well kill as many birds as possible while I’m in there ��
 

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Am I missing something here?

Surely as long as a lead goes from a coil pack to a plug it will work. The ECU tells which coil to fire and when, the spark plug leads merely carry the spark.

In other words as long as each plug has a lead connected to a coil pack it will work.

Up to you how you work the numbers.
 

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mgf
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Discussion Starter · #20 ·
I thought that, Ian. I’m just curious as to why the leads are then specifically numbered. What’s the point of doing that if it does not matter??
 
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