12 replies to this topic

[benmoffat]

Hi,

Justt wondering if anyone can tell me how likely it is to get a new spark plug thats faulty? Has any one had one before?

After running issues Ive been having it went into a garage, I was 130 miles from home and so had to leave it there for them to look at. I had loads of mis firing and stuttering and the next day it would not start.

Have spoken to the garage and they reckon its ok, just one of the plugs was faulty. (I fitted new leads, plugs, rotor arm, cap and coil a week ago) Just wondering if this can be the only problem.
As my worry is Ive now got to drive it the 130 miles back home, a journey Ive done twice with the Mini, and twice its had this problem and nearly broken down.

Thanks

Ben

[biggles1293]

Hi,

Justt wondering if anyone can tell me how likely it is to get a new spark plug thats faulty? Has any one had one before?

After running issues Ive been having it went into a garage, I was 130 miles from home and so had to leave it there for them to look at. I had loads of mis firing and stuttering and the next day it would not start.

Have spoken to the garage and they reckon its ok, just one of the plugs was faulty. (I fitted new leads, plugs, rotor arm, cap and coil a week ago) Just wondering if this can be the only problem.
As my worry is Ive now got to drive it the 130 miles back home, a journey Ive done twice with the Mini, and twice its had this problem and nearly broken down.

Thanks

Ben

Just because something is new is no gaurantee that it is of a good quality, doesn't happen often but don't rule it out, is the garage that has your car a Mini friendly place? You have gone down the right route by changing what you have, but you haven't mentioned anything about timing or fuelling, also check that you have the dashpot topped up with the lube of your choice, some use Halfords classic clean engine oil, others use 3 in 1, but a low dashpot can cause all sorts of issues, have you been driving in lots of rain? The electrics tend to put up a fight if wet - What colour were your spark plugs when you removed them, so check all of this and it may well be worth getting your car on a rolling road to see what it's upto

[benmoffat]

Hi, thanks for the reply.
Its just a general garage, was the nearest one as I couldnt start or drive the car. They seemed genuine enough, just seemed an odd cause to me.

The timing is correct as it was only set by Slarks last week. The dash pot oil was topped up about 2 weeks ago, how often does this need to be checked/topped up? (I had no idea you had to do this, but a trip to a fellow forum member helped me out on that one, it was low at the time)

I cant say about the fuelling, I can only assume its ok as Im getting reasonable mpg and when it went on the rolling road (Slarks again, timing was adjusted at that same time) it produced 51bhp which was what was expected of it. Confused my as to how it was running that well a week ago, with all the same bits on it, and then wouldnt even start a week later.

It wasnt that wet when I was driving it, it didnt rain and when I looked at the distributor it was dry. The next day was dry too when I tried to start it.

When I removed the old plugs they were black, covered in a soot type substance, I assumed this was normal for old plugs. The leads had a greeny and white powder substance like you get on copper pipes. The new ones still look alright, apart from the one that goes to the coil, that looks discoloured, dont know why.

I just really dont want to get stranded in it on the way back. And I have no confidence in driving it and getting to my destination at the moment.

Edited by benmoffat, 30 November 2009 - 04:35 PM.

[lawnmowercrap]

Its very likely. You should always check / reset the gaps on a new set of plugs before fitting them.


I bought a set for mine and all was well, then a couple of days later I got an intermittant misfire. Then it turned into only running on 3 cylinders.

Swapped over the spark plug that clearly hadnt been doing anything (easy to tell by the fact its soaked in fuel) back to one from my old set and all was fixed.

[benmoffat]

I see, thanks lmc, I didnt know you were supposed to do anything to the new plugs, thought you could just fit them as is.

How do I go about setting the gaps on the new plugs then? Sounds similar to mine, was like it was running on 3 cylinders.

Garage say it was 1 faulty plug and they replaced it and its fine, but they didnt say anything about setting the gaps. I assume they would know like you, and would have set the new one they replaced, but may not have touched the other 3 I put in, will have to do those when I get it back.

Edited by benmoffat, 30 November 2009 - 04:40 PM.

[lawnmowercrap]

I see, thanks lmc, I didnt know you were supposed to do anything to the new plugs, thought you could just fit them as is.

How do I go about setting the gaps on the new plugs then? Sounds similar to mine, was like it was running on 3 cylinders.

Garage say it was 1 faulty plug and they replaced it and its fine, but they didnt say anything about setting the gaps. I assume they would know like you, and would have set the new one they replaced, but may not have touched the other 3 I put in, will have to dothose when I get it back.

Assumption is the first mistake lol. Thats what i have always been told.

Basically, some plug manufacturers have a default gap at which it will spark, but perhaps isnt the best spark you can get.
And, you dont know if some doughnut has dropped the plug on end, bending the electrode or something.

Have you got a haynes manual? It tells you the correct gap in there. You'll need a set of feeler gauges, about £2 at halfrauds.

Just push the correct feeler blade into the plug gap and it should have what feels like a magnetic resistance. Tight, but not too tight if you know what I mean lol.

Lee

[minimat]

In approx 15 years of working on general cars as well as mini's i have only had one faulty spark plug so although it is not impossible it is very rare,Ngk's for me every time!
I always keep an old set if they were still working ok for emergency purposes as well.

[benmoffat]

Ok thanks for that Lee. Good point about it being dropped, quite likely I suppose.
I have got a Haynes manual, I wil look it up in there, dont have any feeler gauges but will definately make a stop in Halfords tomorrow.

Cheers, Ben

[benmoffat]

Thanks Minimat, the ones I put in were NGK too.

[jaydee]

Was the heat rating correct? Resistor type used with resistor ht leads?
by the way i use ngk only because thy're cheapo..i've found Champions are loads better.

[midridge2]

in the original post you said it would not start, one iffey plug will cause a missfire but would not stop the engine from starting.

[taffy1967]

Was the heat rating correct? Resistor type used with resistor ht leads?
by the way i use ngk only because thy're cheapo..i've found Champions are loads better.

I've only ever used NGK because they came highly recommended by many and I've not had any problems with them myself.

[lawnmowercrap]

Was the heat rating correct? Resistor type used with resistor ht leads?
by the way i use ngk only because thy're cheapo..i've found Champions are loads better.

I've only ever used NGK because they came highly recommended by many and I've not had any problems with them myself.

NGK are by far the best plugs ive used on my car. I've tried bosch and champion and didnt like them. Even the 4 prong plugs are pretty shocking.


NGK all the way!