Missing tb42

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Hi I have a ford maverick I have changed the plugs the leads distributor cap rotor button coil. It has a Petronix series 1 electric ignition in it so no points. I have also put a new inlet and exhaust manifold gaskets on it. But it still has a mis.
When I have it running I take one lead off at a time. No 1 & 2 led when off one at a time I have no change in the engine but when I take no's 3, 4, 5, and 6 the engine runs ruff.
My question is could it be the Petronix or some thing else?
Thanks In advance
Russell.

[Robo]

So idle stays the same on cyl 1&2 meaning they are the suspect cylinders.

try closing cyl 1&2 plug gap by .2 and see if miss disappears.
what brand plugs ?, Think the consensus is NGK is the premium plug to use.
also after market caps seem to have a bad reputation from what I read on here.
you know to be gentle with carbon leads.
check leads resistance readings.
2 cyls side by side, try doing compression test. ( to be sure to be sure ).

also at night in the dark no lights on, pop the bonnet and look for way-ward sparks arking.
look for burn marks on leads where they touch one another.
may look like carbon like deposits on the leads surface, tell tale of elec arking.
miss in tb is very common from the amount of posts.
it's not duel fuel?.
an extended rotor helps to eliminate miss with duel fuel.
lpg being dry type fuel doesn't help spark to jump plug gap,
a longer rotor lessens the resistance in elec circuit helps to overcome this problem.
another reason closing plug gap is also the go with duel fuel.

[pearcey]

G`day mate
Try a compression test sounds like a blown head gasket or a crack between no`s 1 & 2 cyls .
If it`s on gas quiet possible a cracked head

[gooch]

How do you do a compression test?

[kevin07]

first you would need a compression tester after you had one you will know what to do but in the mean time take it to a mechanic to check it will take 5 minutes

[GQ TANK]

carby

Is it constant across the rev range?

is it back firing

Is it doing it on petrol and LPG

If head - have you checked the oil for "milk", removed the radiator cup and run the motor - did you get bubbles or a fountain?

What coil are you running

Are you running a ballast?

I just went though the same problem

[Virgil9]

Hello, hopefully post is still alive. My gq ia currently having simmilar problems. Missing and rough and tacho flickerd bad when the engine misses. It has new plugs leads and points in the dizzy cap. What i have found while removing the leads one at a time whilst the engine is running is lead 4 is receiving no spark from the dizzy. If i remove any of the other leads the engine noticeably changes tone and boggs down and i can see spark from the cap. Im not to sure why i wouldnt be getting spark at one lead. Tips or checks to do much appreciated.
Cheers Virgil.

[taslucas]

Hi mate, I've replied in your other thread

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