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Coil Pack or HT lead.Esprit S4

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Hi my S4 has an electrial fault on one of the cylinders,I have traced it back to the ht lead which I will check tonight.If the HT lead is ok can the coil fire on three or will it completely break down,Cheers Paul.

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The S4 is a wasted spark system (also know as distributorless or DIS) so 2 cylinders fire at the same time. It has 2 coils in the pack and each coil fires two cylinders.

If one cylinder is misfiring it should be possible to swap leads around at the coil pack to see if the fault is with the coil pack or cylinder.

No 1 and No 4 are paired and No 3 and 2 are paired. If for example No 3 is misfiring swap the leads for 2 & 3 around at the coil pack. If the fault jumps from 3 to 2 then its the coil pack. If the fault stays with 3 then its the plug, HT lead or a mechanical / fuel issue with the cylinder.

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More than likely the coil pack number two and three are prone to water ingress, you could try cleaning the connectors as they will more often than not be green


It's Oogies turn to boogie

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you can also get msd ones from the usa which work out cheaper. also look at the backing plate on the coils the bottom bolts (5.5mm) earth them, if you end up replacing the coils its worth putting an extra earth on, i linked both bottom bolts to each other then ran an earth from them.


It's Oogies turn to boogie

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Peter has the correct idea.

Right below the coils, on the chassis, you will see an empty stud. I found that it was a perfect location to place extra earths.

I run the MSD coils. A vast improvement over the stock...however you do have to make the earth connection a bit more improved.

Similar to Peter I ran an earth from the plate that attaches to the engine bay to the empty stud located on the chassis. I then removed the coils and placed some diaelectrical grease on the connector back plate to the plate attached to the engine bay and a bit on all the connectors of the coils to help avoid the water corrosion issues.

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Thanks,what I have found so far is that nos3&2 are playing up.No 2 has a feeble spark and no 3 has none ,it looks as though there is not enough energy to get to no3.When I remove no2&3 there is no change in engine noise so I think I have located it.I will take the pack off tonight and clean it up and see.If I have to get a new one I assume that are plug and play,is this correct? Cheers Paul G.

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Yep plug and play, note that water can get inside the coil (mine did this) and it was not visible until I cut the coil open with a dremel. I use to have a spare coil pack , I will look tonight to see if I can find it


It's Oogies turn to boogie

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Not sure of the specs on the coil packs as I have not had to fault find anything with them as yet, but they also look suspiciously identical to the ones used in the Holden Commodore so I wouldn't be surprised if there is a Vauxhall in the UK that runs the same packs.

Can't guarantee it, but worth the question.


All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

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When i did my engine clean up the other week i put new magnacor leads on, which if you are running the originals I would recommend you do. When I took the old leads off the coil pack I was amazed at how much corrosion was on a couple of the terminals. 10 mins with emery cloth took care of it but a set of MSD coil packs is on the shopping list.

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I just swapped the MSD coils into my 93.5 today. It was easy. As someone esle pointed out, you'll need a 5.5mm socket. I think that was the first time I've ever used that socket in 20 years of owning it. ha! I may look at added a grounding cable as a few of you have suggested.

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Hi All,

I developed the exact same fault the other day. Have checked/swapped leads around but whatever I connect to no.3 on the coil pack, there's no spark. Fairly sure no.2 is working fine though?

Would this suggest it is the coil pack itself or just an earthing issue. There's absolutely no 'green' on any of the connectors. Is the earthing issue more likely to be on the backing plate?

Finally, I was unaware that it is 2 separate packs so presumably I only need to replace one?

Having just seen SJ's price, can anyone confirm that the M100 is the same? Apparently its also used on the Lotus Carlton.

 

Any thoughts most appreciated as always.

 

Nick.

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Very easy to check a coil lead.  Set your multi-meter to 'ohms'.   One probe at each end.   Expect to get a reading of between 10 to 15000 ohms.  No reading means no continuity and the lead has broken down.  Anything too high (maybe over 30000)  resistance

too high.  Roy.

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I swapped 2 and 3 and tried both with a loose plug, 2 is firing 3 isn't ??

 

Initially I suspected it was #3 lead, but when I swap it to any of the others it is firing?

Edited by nickh

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Update.

Problem temporarily solved. I have found by default, that with the bottom mounting bolt removed from coil pack 2/3, that all is working fine again!

As soon as the bolt goes through the hole in the coil pack, without it even taking thread in the mounting bracket, then the problem reoccurs.

I can only assume at this stage that there may be a hairline crack in the coil casing which is then causing it to earth out through the bottom bolt.

 

I have an NGK replacement pack on order anyway, so will have to see if this solves the problem entirely, or indeed if it works at all.

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Msd 8224 I think are the replacements at 44 quid each. A common fault is that the casing cracks. I removed mine when the engine came out for service in April to find one had split on the underneath of it..invisible from above. .simple fix and not expensive

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