Misfire questions

[toomorecol]

Hi All
I am pulling my hair out over a misfire, I searched all the misfire questions but still no answer.
So 1098 traveller, ticks over like a fine woman, stars on 1st turn of starter even after the misfire trouble, goes 1/2 mile and then a little misfire but hit a hill or get up to 50 and the misfire gets bad, so what have I done so far, new dizzy cap and leads, new plugs, new points, new capacitor, metered out ground lead on dizzy and all other leads all ok, checked out fuel filter and it was clean, float bowl had a little sediment in it, metered out coil all within spec but have ordered a new one although the thought seems to be from a search is that coils live or die completely. Removed petrol filler cap to check for vacuum in petrol tank all ok. Carb dashpot full of oil no binds in dashpot. Now I found one problem in that sucking the advance retard tube dosent move the advance, however and it seems most think advance retard failure will not cause misfire and that seems logical, of course i will fix this once my baby runs right. The suction is solid so the diaphragm has not blown, even if I blow its solid. Ok one will say my advance/retard failure is the problem and great i will get a new dizzy but I cant see how a few degrees out of timing will cause a misfire, put me right if I am wrong.
So bearing in mind what i have done any good thoughts appreciated, and yes I know there are some crap parts around but to buy another set of bad parts !!
Technically I will ask is there a easy way to separate fuel starvation from electrical, I would say i have a electrical problem. Ie I would expect fuel starvation to cut out completely for say 100yds then cut back in whereas electrical to be on and off all the time. But put me right if I am wrong.
By the way all my plugs come out perfect colour as per champion colour chart, and yes I tried pulling out the choke on misfire so its not a weak mixture, no pinking, no popping from exhaust.
All help appreciated
Col

[sgray]

I had a terrible misfire problem which was down to loose riveted spade connectors on the coil. Changing to the other two connectors cured it immediately.

[PSL184]

You didn't say if you had changed the rotor arm?

[bmcecosse]

Obviously - the vacuum advance should be sorted - you don't need a new dizzy - just a new vacuum unit. Better check the valve gaps - 12 thou inlets and 15 thou exhausts, and then a compression check would be good. It may be the rotor arm if you haven't changed it - but maybe you just forgot to mention it since you seem to have done everything else!

[toomorecol]

Hi
Yes rotor arm changed, I have worked on engines DIY all my life, to be honest valve clearances too big and engine is noisy, sounds like a bag of nails, runs crap but dosen't misfire, too small and it dosent misfire but ticks over bad, a small valve clearance lets in less air, eratic tick over, low compression on one cylinder i would expect a sooty or oily plug all plugs are perfect in colour as per champion colour chart. Low compression is either rings gone or valve not seating, rings gone is oily and sooty plug and inlet valve not seating is backfire in carb, exhaust valve is bang in silencer. My experience is mainly with motorbikes so some expert on Moggy's will put me right and thanks. I am not saying valve clearance will not give a missfire but they will also give bad starting and poor tickover.
Ok today I went into Halfords to save postage and asked for a coil (non ballast) and Halfords dont do coils, what do cars run on!! yea electronics. Think i have lost touch of modern cars, Ok one here tomorrow from ESM always next day on delivery from them.
I dont think its the coil but a last resort
Actually I think the vac unit is Ok as there is pressure on it sucking the pipe but no movement on the dizzy which says the advance mech has seized but would that cause a missfire!!
So Tomorrow i will pump a gallon of fuel through the pump to see if it delivering enough and pray that the coil fixes it, failing that a kick up he backside.

[bmcecosse]

So - you aren't going to bother checking the valve clearances -and then running a compression check ? Up to you - it's a very basic health check for the engine. The problem with 'stuck' vacuum advance is that it fools you into setting a false static ignition setting, and could very well lead to mis-firing at higher revs. But again - you seem to know best!
I'm not sure why you bothered to post up this thread - since well meant suggestions are discarded out-of-hand!
It certainly won't be the coil - although it could be - as suggested earlier by 'sgray' - bad connections at the coil.

[toomorecol]

So - you aren't going to bother checking the valve clearances -and then running a compression check ? Up to you - it's a very basic health check for the engine. The problem with 'stuck' vacuum advance is that it fools you into setting a false static ignition setting, and could very well lead to mis-firing at higher revs. But again - you seem to know best!
I'm not sure why you bothered to post up this thread - since well meant suggestions are discarded out-of-hand!
It certainly won't be the coil - although it could be - as suggested earlier by 'sgray' - bad connections at the coil.

Sorry if I upset you I think aloud, no harm meant and i did say coil was a last resort, but in desperation you try everything, as for valve clearance give me some technical reason and i will do it but my valves were adjusted 500 miles ago.
I like this site but i want technical answers and one person out there has the exact symptoms and hey presto the answer.
You know 1 yr ago my half shaft snapped and jammed in, the grooves on the diff end had twisted and distorted I could not get the shaft out, this site did not find the answer, it had jammed on the diff bearing, the solution was draw it out with small nuts and bolts between the half shaft end and the axle end a very slow process, I had to work it out myself as we do at times.
If this is the best this site can give me well
Col

[autolycus]

Entire post deleted in case the OP thinks it's not technical enough (see his comments below)


Kevin

[bmcecosse]

You hadn't mentioned that the valve gaps had been recently set - I can't read minds.......... The idea was to set them correctly - AND THEN do a compression check.......

[toomorecol]

You hadn't mentioned that the valve gaps had been recently set - I can't read minds.......... The idea was to set them correctly - AND THEN do a compression check.......

Think before you speak
You have really [Don't swear or you will be banned - Admin] me off,
I want technical answers not crap.
Col

[bmcecosse]

Good luck with that misfire........

[alanworland]

Sound information given in good faith - take it or leave it!

[LouiseM]

Everyone on here tries to be helpful. There's no need for rudeness or bad manners

[toomorecol]

Ok I upset you all, its life.
Once i fix the moggy she is for sale, cost me 3 grand
I will put her on Ebay at 2 grand starting when i fix her, give me a grand and half and its yours. £1500 I am just fed up.
Good luck to you all
Watch out for her she will get 3 grand
Col

[aupickup]

hi
do you have any photos of the car please

[Alec]

Hello Col,

I may have missed it but have you checked the coil polarity?

Alec

[toomorecol]

Ok I am back again to apologise, i was out of order, stress got to me, my apology goes to bmcecosse, I have calmed down now and followed your thoughts, followed your comments (bmcecosse) , checked my valve clearances all ok, bought a compression gauge, cylinders read no 1 158 psi, no 2 145 psi, no3 130, no 4 162. Ok I am open to advise, I think I need to decoke and grind in the valves, the top of the pistons look very black and coked up as seen through the spark plug hole. Do you think this would be the cause of my misfire if so i will take head off. One thing I found is the dizzy wire to coil was very frayed so i renewed that but still a misfire, but its not as bad, and i renwed the vac advance.
I love my moggy, I can only say sorry to all, I thought i can fix it, its a simple engine. You cant overcome experience and many of you have tons of it.
You learn by mistakes in life.
Col

[mike.perry]

The check that I always fall back on for tracing a misfire when all else has failed is to run the engine in the dark and watch for any stray sparks, HT leads arcing or touching the bodywork somewhere. It has traced a few misfires.
Somehow it is always easier to identify a problem when you are stood over the engine than when you are sat at a keyboard, when you can miss the obvious.

[toomorecol]

Yes, Done that in the dark, touched lead against lead and no shorts.
Col

[linearaudio]

What about that little braid earth wire in the dizzy, between the base plate and the side? Easy to overlook, can fracture and still look OK, earths intermittently as the base plate moves. Certainly had me cursing until I discovered it was broken!