15 replies to this topic

[Chadders]

hi everyone

 

Was hoping for some advice on what to try next with the misfire I thought I had fixed, but has returned after 2 weeks (3 drives - occasional use car)

 

If I drive from A-B normally without much acceleration its fine.. The problem occurs when I used 3/4 - full throttle over 3,000 rpm.

 

I did have the problem before like I said and I replaced the plugs, leads, dizzy cap and rotor arm, made sure the carb dash pot oil was at correct level, and after 5 mins of driving the problem went away... only to now retrun again.

 

any ideas?

 

only other thing to note is that a previous owner much of ruined the thread in the dizzy for one of the cap bolts, so that has always been held on by a cable tie.. when I changed the dizzy cap, srewed in one bolt and then used a new cable tie and secured the other side very tightly.. Obviously it sounds like this will be the problem, but the dizzy cap appears very secure!

Its not been driven in the wet at all in this time.

 

Engine is a 1275 MG Metro

 

many thanks

 

 

[mini danny]

My 1330 done this. Chased it for ages and turned out to be the coil. If you have a spare coil try that.

Dan

[Chadders]

Ah it has had a new coil mind, the previous owner changed the coil not long ago... end of june i think... But I guess thats not to say its not faulty

 

cheers

[mini danny]

I would still check the coil mine was 3 days old and made mine misfire. Make sure you have the correct coil for the ignition system you are using. Are you running points or electronic ignition ?

[Chadders]

cheers dan, its electronic, As far as I know as standard on MG metro engine

[mini danny]

No worries and I fitted a coil just from my local motor factors. When I then took my car for its tune up after running it in was told the coil was no good for my electronic ignition and was told the best coil to use was the Lucas DLB105. Stuck one on and hasn't missed a beat in a year and runs even better now.

[Chadders]

dug out the invoice for the coil.. and googled the part number.

came up with this one on minispares and from the description it does appear to be the correct one

 

http://www.minispare...|Back to search

[mini danny]

Ahh that's good then. I would still try a coil just to iliminate it.

Dan

[Chadders]

I might as well give it a try mate, will pass by minisport next week and pick one up!

 

chadders

[mini danny]

Good man let us know how it goes

Dan

[Chadders]

will do 

[Stevie W]

Hi,

I agree with Danny. I had a misfire at around 4000rpm on my Mini and spent ages replacing most of the ignition system only to find it was the coil all along! Eventually it gave up completely on the way home one day.

Looking at the coil after removing it from the clamp, the coil can had been punctured by too tight a clamp and the primary windings were visible through a small hole. Once the coil warmed up, the windings broke down and the misfire started.

Not saying this is your particular problem, but it is one that can (and did) happen to me!!

Cheers, Steve.

Edited by Stevie W, 19 October 2015 - 06:02 PM.

[adam_93rio]

I've chased a very similar problem across 3 engines in mine.
Realised it did it worse if it was running on choke when cold morning came. Turned out to be wear in the carb (probably the needle/needle seat) causing it to be too rich at higher revs/full throttle.

I've just backed my mixture screw off to lean it out loads, I don't really use it much at the moment so it's a fix until the new fresh engine is put in

[jaydee]

That misfire is typical of a LT low tension circuit fault, which means either the coil connections are loose and not prividing good current under vibration or the coil is fried

BUT beware that since you'reusing a 65dm dizzy (mg metro engine) you need the appropriate coil or you damage the ignition module. So if you had the wrong coil its likely that you need to replace the module aswell.

Intermotors provide good quality coils, lucas not so much these days.

Edited by jaydee, 20 October 2015 - 11:01 AM.

[Chadders]

Thanks for all the replies.. it does sound like I need to try a new coil next. Not had chance yet as been busy with work but by next weekend I should know if thats the problem

 

will keep you posted!

 

Its strange how changing the other ignition parts seemed to fix it for a short time though!!!