Misfire Again

[ham204]

Having changed the dizzy cap ( twice), leads (twice), rotor cap (x2) and fitted a lumenition igniton module MTK007 plus MS3 coil and new plugs, I thought I should be able to put the misfire at lows revs to bed. But no deal - the car misfires exactly the way as the day I got it. The PO said that it was probably an air leak somewhere but a change of manifold to carb gaskets to alloy ones made absolutely no change. I tried putting a little washer to raise the rotor arm and no washer but the result is the same. Carbs have been dismantled, valves and floats changed and set properly. New standard needles (BBT) have been fitted. It's embarrassing to drive, sounds like a VW Beetle. The only thing that I can think of that has been untouched is the distributor. There is more than a slight movement in the shaft but not too much.

Is it worth getting it reconditioned or I am barking up the wrong tree (again!!) ?

[Mahesh]

Might be worth checking/cleaning coil spade/ring connectors for a good contact and also fuse box.

Is your dizzy base plate earthing lead present and in good working order/continuity ?

Only things I came across in my car,.

[soe8m]

What rotor do you use?

Jeroen.

[epcot_pete]

I had a similar problem with my MGB and I bought a set of those transparent test caps that fits between plug and HT cable. Especially when dark you can see the firing sequence at low revs and spot which one is missing. It will tell you if it is electrical or fuel. The worn distributer should not make a miss-fire, just not fully efficient, so I would go along with Marhesh's comments.
Hope that helps, and totally understand for frustration's!!!!!!!!

http://www.ebay.co.uk/itm/Sealey-VS5261 ... SwZJBX97XV

[Jon Tilson]

Does the misfire change if you pull the choke out slightly? What plugs are you using?
Have you looked at them to see if the colour of one is a bit dark?

I would try bosch platinum plugs which I think you can still find on ebay in Sprint format.

How is the lumenition powered? Is it from the full battery volts or a ballasted coil plus? If the latter - that's your problem.

Jonners

[ham204]

Does the misfire change if you pull the choke out slightly? What plugs are you using?
Have you looked at them to see if the colour of one is a bit dark?

I would try bosch platinum plugs which I think you can still find on ebay in Sprint format.

How is the lumenition powered? Is it from the full battery volts or a ballasted coil plus? If the latter - that's your problem.

Jonners

Thanks to all for your posts

Jonners - yes the engine settles down of I pull the choke slightly. The carbs are both balanced and Co2 is set at 3.85
The plugs are black but the car was only being used in the garage so that may be misleading
I had Bosch plugs and they all failed. I am using NGK BP6ES
The lumenition is powered by the coil! How do I rewire to take the battery voltage? Specifically is the dizzy red wire sent to the battery + terminal? And what about the coil + terminal? Is that wired to the battery also?

[Triumph1300]

3.85 will pass an mot, and lead to a car that runs badly, they need to be at least 5, or 6%.

Better being set by ear, after a good run.

[Triumph1300]

The red of the lumenition needs to be taken to the ignition side of the fuse box.
Unless you know what the coil is, don't touch the existing coil feed

[Mahesh]

The red of the lumenition needs to be taken to the ignition side of the fuse box.
Unless you know what the coil is, don't touch the existing coil feed

Absolutely, the red lead from the lumenition to the fuse box, if you want I can take a pic for you at the coil and fuse box, if you do a search Jeroen recommends a fuse on the module lead (something I have to do and check it was the black lead)

[ham204]

SO....I just remove the red wire from its existing connection on the coil and fit to an ignition fed power source right?

Apologies but having had a (small) fire in my 1300FWD dash I am VERY careful now about connections!!

[tangocharlie1]

Found this diagram hopefully makes it clearer. I think what the guys are saying is cleared up by the one paragraph at the top.

[ham204]

Yes, that is clear enough, thanks.

I'll try it out and see if it helps.

I don't actually know if my wire is ballasted or not ( I suppose it is) - so there is no damage if I wire it the same as above in that case?

[AlanH]

I know this sounds a bit drastic, but could you get hold of another set of carbs?

I had a similar problem on my 1850 and went through all of the things that you have.

In the end I took the carbs off of my Herald and tried those. Things improved straight away.

I ended up swapping them back one by one and found the offending unit.

Edit :-

Try the drop test on your carb. pistons.

[Jon Tilson]

Take a wire from the ignition fed fuse at the fuse box and the unfused (white ) side. This is very important as if your fuse blows your
ignition will also cut out - could be dangerous.

Join this to the red feed on your lumenition and keep away from the coil plus, which if standard will be ballasted.

Lumenitions run for a while on a ballasted feed, but then start to give your sort of trouble.

I would also say the CO is too low and should be in the 5 - 6 % range so this is also contributing.

Jonners

[ham204]

My comments below:

Take a wire from the ignition fed fuse at the fuse box and the unfused (white ) side. - So two wires then, one from the unfused and the other from the fused right?

Join this to the red feed on your lumenition and keep away from the coil plus, which if standard will be ballasted. - this is the part I cannot understand - so the coil will finish up with the black lead from the dizzy and the red terminal will remain unconnected except for the lead coming from the dash?

I would also say the CO is too low and should be in the 5 - 6 % range so this is also contributing. - this will be fixed. I had the equivalent of your MOT here and the tester is never happy with anything above 4%