Are you sure its the coil packs? Sounds odd to me.

 

How did you check/test the coil packs to decide they were the cause?

 

Didn't check them just swapped them out as I had a spare and it seemed to be the likely cause and the car started performing as it should again with no juddering once the replacement was put in.

 

check you have the correct spark plugs they may be the cause
Ron

 

Total WAG (wild-arsed guess) but usually high-tension devices like coil packs would degrade due to insulation problems. There might be two causes - either they are getting contaminated somehow or perhaps there is excessive HT due to the spark plug gap being way too wide - this might eventually cause internal breakdown. You'd need a Megger to check for that (insulation tester) and I don't suppose you have one but as the previous poster suggested, look at the plugs.

As for contamination, a wash of your badly performing coil packs in something like alcohol (meths I suppose is near enough) might be worth a go - dry them out thoroughly before reuse.

 

Don't rule out other sources. I had the same problem that was fixed for a couple of weeks when I replaced my coil packs but it turned out to be the lambda.

 

As long as we are on the subject of coil packs, has anyone tried using aftermarket coil packs for a better spark, better reliability?
They are very popular with the hot-rod crowd over here.

 

Ive just bought a pair for my engine.. before doing so I asked various Lotus and K series 'gurus' if there were 'uprated' or improved coil packs out there..

They all said the same.. use stock coil packs, Magnacor leads and denso plugs

So ordered Magnacor leads from DC Performance, coil packs (OME) from E bay and will swap to Denso plugs once the engine has had its 50 hours running in on tick over

 

I have recently used various coil packs on my Elise S1 and the conclusion is quite clear: whereas aftermarket solutions, enhenced or cheap, worked OK on the road they ALL lasted less than a day on track (admittely driving hard on curbs and hot day).

On my car I had the std Rover bits, they lasted over 100 track days, I had to replace them at 130 000km and as 2 aftermarket bits failed in a row I went back to std and since all is OK (5 hard track days). Don't buy cheap!

As of leads, I would also recommend the std item. I tried 2 magnecors, blue and red if I remember, and their insulation was just crap after 2 years under the rain (I had a visible christmas tree all over the engine with lot of misfires at Le Mans). Since, I moved back to std and not upgraded and all is fine. The problem is lead age with time and use, they need to be replaced every 5 or 7 years or so.

To get the best on the S1 (not S2, so TF etc. don't suffer from that) I also needed to insulate the plug cover to stop water ingress (on both long sides and on the small left side). I can see that due to heat the leads can also melt on that small side so need to think about it to avoid contact with the head. Some leads are also porous, even when std... Apart from the last bit, all shouldn't be a real problem on MGs as the engine is not exposed to rain whereas it is on the S1.

My advice, based on road, track and race experience with quite a few Elise, would be : standard coils and leads. Beware also of cheap copies on the internet, OEM is sometimes not what it is supposed to be, especialy regarding coil packs as a friend of mine found out. If cheap on Ebay, run away, it simply can't be. Look for an official Rover parts dealer (Rimmers etc.). As all these parts wear with time it is also not worth purchasing 2nd hand, as it will fail again quite sooner (and is quite a hassle to replace re access on an Elise at least).

Our MG is a TF so obviously all very different there, quite more reliable and straightforward in that matter (different parts and technology, different engine cover), as are Elise S2.

Good luck

Claude

 

Thanks for that Claude, That's good info. My coil packs are OK for now but I worry about the quality of new OEM style replacements currently on offer. They may look like the originals but who knows what their performance will be like?
Here in North America there are performance coil options from companies like Accel that cater mainly to American vehicles but as long as the specs are similar they should be usable on an MGF. There are also other manufacturers OEM coils. I had a Megajolt system on another car and it used Ford Escort coils which worked well.
I do have to admit that I have been disappointed with the performance and longevity of much of the aftermarket bits I have bought for my MG, and should smarten up and just stick to stock!

 

Some aftermarket stuff is better.. But some OEM stuff can't be beat..

This goes for stretch bolts for the head.. Hellier says he has tried the others but only fits OEM now..

The coil packs I bought off e bay come in packaging which looks OEM.. They look OEM and were indeed sold as OEM.. They could be fake.. But seriously who is going to go to that much trouble to fake 2 coil packs?

 

Sadly quite a few... There is quite some money to make with very cheap coils sold at OEM prices, but then they won't survive heat and vibrations aswell, or not all of them (1 out of 2 as for me?).

IF you really can't find true OEM, then for a similar price you can fit Renault coils as these are nearly the same (but no back plate). They are sold now directly through Valeo who advertises them as being compatible for MGFs (indeed same electrical specs and they do last for ages regardless the use, so can be considered as real OEM quality). Some race cars fitted them with success over the past 3 years.

But as the real Mc Coy is still around for the same price, why bother... As long as it is 100% the real Mc Coy.

Race (ab)use is indeed extrem and some Ebay stuff might again well cope with normal use. However, track also reveals longevity problems, so I can't help thinking that the ones that failed after 1 track day will fail sooner than OEM when used on the road only. OEM coils can last up to 10 years, road and track... Hassle free. AFAIK coil discussions surfaced to my knowledge about 6 tears ago when... some drivers basicaly went for non OEM parts.

Have fun

Claude

 

My engine is Mems3 so wasted spark top mounted coil packs.. which I'll probably junk every 12 months anyway...

If mine are fakes.. they are damn good fakes.. cos they look OEM and so does packaging..

Time will tell

 

As said I was refering to MGF and Elise S1, as said S2 and our own MGTF have indeed completely different coils, integrated in the leads near the plug.

These are indeed unlikely to be copied and are more robust. Even if copied they are probably less critical.

As the orignal poster I am refering to coil packs, as the ones you find on early VVC engines, mounted on the side of the engine and quite exposed to vibrations and heat. Connectors are also known to be a problem and can be replaced with Bosch items (done it but can't recall what I used). The standard connectors from the ECU are very flimsy.

I hope this helps

Claude