Poor running after service plugs and Ignition leads changed

Hi all, my first post here, I’ve spent some time browsing and searching the forum to find similar problems, which has helped but looking for advice from folk who’ve had a similar experience with the garage/servicing issue and also what the problem might be so I am clued up when I take the car back next Tuesday for them to “hopefully” fix!

Ok so I own an MX5 mk2 1.6 registered in '99. I’ve had it for over a year and it passed its MOT early November no problem, only advisories are corrosion and worn brake discs. The previous owner is my father who owned the car since 2004 when it had 12,000 on the clock, one previous owner. Its now on 66,500. So I’ve actually been driving the car on and off for a long time and he looked after it and has its got a full service history from main dealer Mazda garage, Johnsons on Botley Road in Oxford.

So breaking with tradition! I just got the MOT done at my local garage with a discount and saved some cash. it was also due a service by November which I have been putting off but it was within the suggested mileage so I decided to get it done and went for service at Johnsons, 30th Jan, as the price was slightly better then what my garage offered for a Level 2 service which includes changing the spark plugs. The only issues I had was that the brake warning light had been on for over a week, handbrake definitely was off. They said they would check it out.

It was all straightforward until after the service was finished, they told me no problems found apart from those advisories from MOT (and there was also no brake warning light coming on as I had said it was) and so I paid and begun driving home. Its only really a quarter of a mile till you get onto the southbound A34 and thats when I realised that the car was not performing as well as it used to. The engine feels a bit lumpy and then when at slower speeds or just idling it was more noticeable. I rang them back as soon as i got home (near Didcot) and told them of the problem, they said bring it back in the next day, so I did that and hung around for maybe an hour or less while someone checked it out. After this they basically said I needed new ignition leads and it was definitely that no question as the car had new plugs in the service and the leads must be worn out. So asked them how much and they said £146 (genuine part something like £75 +VAT and half hour labour) and I’d have to wait 3 weeks for an available slot! Anyway I left and had a chat with a mate who said that was very expensive and its a simple job parts available online etc.

Anyway ordered good quality 7mm ignition leads from mx5parts and had to wait a week for them to arrive what with the snow and all. Done the odd short local trip in the car, still the same. I also noticed for the first time when I had moved the car that there had been a small oil leak on the drive under the middle of the engine/sum area. Leads came yesterday, straightforward job, changed over and made sure they were connected in the same way as I could see the existing ones, all push on firmly etc. Guess what…no change, if anything more noticeable poor running. If I listen carefully when I accelerate it sounds like a lawnmower, like something intermittent. So not happy and called Johnsons and said its their problem to sort out. What really annoys me is that I have paid to have a Level 2 service, and they have said there is nothing wrong with the car except for the aforementioned corrosion advisories and let me drive away. Surely if you are changing spark plugs as part of a service they drive the car around before/ after etc. all I can think is the mechanic has not been paying proper attention to the performance or not driven it far or at all! 

So they said bring it back in and leave it there all day next Tuesday and they will have the head tech look. So I’ve come on here to educate my self and seek advice as to what could be the problem/ how to proceed with the garage etc. I’ve had a search and read of various posts and can see some people have had to get new coil packs. But there was nothing wrong with the cars performance until they changed the spark plugs, ive seen mention of cars running on 3 cylinders etc and I also saw mention of sparking when people have had similar problems so last night we went out and had a look and when the ignition is turned just before it kicks in i can see a few sparks around were the cable connects to the coil pack, looking at the windscreen its the second from the right. Looking back in service record, spark plugs previously changed 2 years ago. When its dark 'm going to swap the lead with he sparking to the old lead and check if it still does it.

Apologies the post is a bit long but Im new here and wanted to make sure all the facts were clear. Thanks in advance for any helpful advice which will be greatly appreciated. One worry is what could happen before it goes back there, should I be driving it at all? Not got any breakdown cover and thinking now is a good time to get some! Back in 2010 it blew a spark plug out so wouldnt want to stress it out and have that happen or a similar catastrophic failure brought on because of its current running condition. Hopefully the will sort it or diagnose properly when it goes in, but because of the experience I have already had it wouldn’t surprise me if they say X needs changing it’ll cost XX and you’ll have to wait till XXX for it to get done! What are my rights if I’ve had a car running fine taken to a garage for a service and given back in a poor state when they have said EVERYTHING is fine?

opps sorry its a 1.6i not 1.6

See if the garage is part of the garage ombudsman scheme. Seems nonsense to wait 3 weeks for parts. Check the oil level then check they have fitted the right plugs. Take each plug lead off in turn and see if one of the cylinders is not firing correctly.

It seems you have had a reasonable time with this car but now need to get your hands dirty:-)

From your description I would guess that coilpack is the issue. Garages tend to leave the ignition on without running the car, expecially at MOT time. The MK2/MK2.5 has the weakest coilpacks of all MX5s and these fail regularly.

I would get an LED error code reader - look up ‘MX5 diagnostic’ on ebay - it’s about 11 or 12 down and costs £8.49 delivered. Use this to see if there is an ecu recognised problem.

Unfortunately coil packs will not register an error code, so if your newly purchased reader tells you there is no problem, it is very likely coilpack.        

Thanks for the swift reply Raymond. I was just going to post an update as I went out swapped that new lead for the old one. With the old lead there are no sparks! Only this new lead do I get 2 or 3 sparks on ignition. took her out for a short run up to 50mph twice, once with this 1 old lead back on and again all new leads, it runs the same on both 2nd gear round 2000 rpm lumpy and 4th gear 3000 rpm same issue. I will go and check the spark plugs now, checked youtube for a vid as not done that before. But how come one of the new leads produces sparks at the end where the old one is fine, should I send them back?

Try this as it’s an easy mistake. Image result for mx5 mk1 firing order

Sparks from the end of the lead fitting to the coil pack suggests the lead isn’t fitted properly. The sparking will burn the insulation. Get a pencil wrapped in emery paper and give the contacts on the coil pack a clean.On the plug lead, you can peel back the end a bit, and ensure that the lead is fitted properly. Maybe bend out the contacts a little. At the other end, take out the plugs and look for oil on the plug or plug thread. Its possible when they were filling with oil, the garage got a bit of oil into the spark plug holes, and that its worked its way onto the plug threads. Usually, though, a drive will burn this off. You might coincidentally have a leaky camcover gasket, which will foul the plugs/ Fitting the plug lead onto the plug properly means pushing it on, then turning it into place.

Well, oil level on dip stick is normal, how do I check if they have fitted the right plugs? I don’t know what the correct spark plugs are and can only see the top but I can say this to them when I take it in. Anyway yes you got it spot on as when I took the leads off number 4 is not firing correctly, car nearly dies when I remove this one. So does that mean a dodgy plug?

 

Sorry I didnt quote before replying earlier, see my other reply below

 

Thanks for the pic but the coil pack in that diagram looks different to mine, but the main difference is if that’s how its situated behind the engine with 4,1,2,3 from righthand drivers side to near side those connections are the opposite way round in mine, see my photo, I have also seen other pictures showing them connected how mine are. 

HT leads MX5 mk2

 

 

Can’t post a picture for some reason, maybe as i have free membership anyway its here: Dropbox - File Deleted - Simplify your life

 

 

 

 

Thanks I was reading about those yesterday, may have to pick one up

 

I took the cable of the plug and there is no oil in the hole where the plug is, but I have just read your post again and I think you are saying remove the spark plug from the engine right? That’s taking it a bit too far at this stage as its going back to the garage on Tuesday for them to look at. Ive never taken a spark plug out before but dont mind getting involved with mechanics if I was doing this from scratch but Im not going to touch anything like that until the garage has checked its work etc. That’s all really useful info though so thanks for the post and I can mention this when speaking to them. At the coilpack end didnt look dirty but can give a clean as suggested tomorrow. 

Cheers 

 

It is not unheard of a new plug being DUFF.

If the one lead is sparking in the dark, I would suspect that plug as being open-circuit, and the spark is needing to go elsewhere, usually via the weakest spot in the insulation.  I have had this happen more than once with brand new plugs in the past, which is why I always keep the old plugs for a few months.

An open-circuit plug will give very lumpy running. It should have been obvious from the start; they should never have returned the car to you like that.

As well as washing down the bore and into the engine oil, the unburnt fuel going through that cylinder can also damage the cat.

I would be very forthright in addressing the service manager.  Polite but firm, asking if they will repair a potentially damaged cat and give the car another oil change.

 

 

You say that when you take the lead off number 4 plug the engine nearly dies…that is what it should do, because you have removed a good sparking plug from the equation.
It’s when you remove a lead and it makes no difference to the engine that is where your problem is.

You say that when you take the lead off number 4 plug the engine nearly dies…that is what it should do, because you have removed a good sparking plug from the equation.
It’s when you remove a lead and it makes no difference to the engine that is where your problem is.

Just noticed you say removing no 4 lead nearly stalls the engine.
This would suggest to me that this cylinder is strong.
Was the engine running sweet prior to this service?

It could be that one of the plugs isn’t gaped correctly, spark plugs should come out of the box with either a cardboard or plastic tube wrapped around the electrode end to stop them being damaged (closed) if dropped or banged about.

If your not thinking when your changing plugs it’s not unknown for the mechanic to accidentally fit an un-gaped plug, i can change 20 plugs a day if there are no brake downs and i will admit i don’t check every one.

Take it back to the garage before you start throwing money at it, and good luck.