flak monkey
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| posted on 23/1/07 at 07:34 PM |
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Misfire
Ok then, need to build up a list of possible reasons why I have a random misfire on cyl 4 of my pinto so i can investigate when i get home. Its ok
ticking over sometimes, mainly when holding around 3000rpm or so.
So far got:
Plug leads (checked with a meter and seem to be ok)
Plugs (swapped around and no change)
Valve clearances
Anything else to add?
Cheers,
David
Sera
http://www.motosera.com
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Johnmor
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| posted on 23/1/07 at 07:38 PM |
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Compression may be different in No 4
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jambojeef
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| posted on 23/1/07 at 08:01 PM |
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Dunno what your Pinto runs spark wise but dizzy cap? Rotor arm?
You will know this anyway but - if you can - swap the leads over too to eliminate those as a cause for sure - even slight changes in the resistance of
the lead or a breakdown in the insulation can cause problems and might not show up on a multimeter test.
And while Im thinking about it - my old fiesta used to misfire this time of year owing to its knack for carb icing.
Fixed with a coke can from the verge by a nice AA man a few years ago on my way home from uni for xmas!
IIRC I had to push it out of the fast lane in the dark up to its windows with stuff for my mum to wash!
(Probs not that anyway but another one to tick off the list)
Geoff
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flak monkey
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| posted on 23/1/07 at 08:02 PM |
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Its running on twin 40 DCOEs at the mo
Cap is new, and looks to be ok. Can try another though.
The ignition is all new electronic fast road spec from H&H ignition solutions. Coil also supplied by them.
If its compression i cant see a solution?
[Edited on 23/1/07 by flak monkey]
Sera
http://www.motosera.com
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rusty nuts
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| posted on 23/1/07 at 08:16 PM |
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Air leak at carb to manifold or manifold to head? spray with wd40 to test. Possible leak at servo connection? Loose or blocked carb jets? As already
suggested compressions? Faulty distributor? the Motorcraft ones were never too good Acouple of tips Iwas given years ago with the Motorcraft item was
to bi pass the small black box on the side of the body and also to fit an extra earth lead from the contact breaker screw to the base plate securing
screw . For what they cost it may be better to substitute the distributor cap and rotor arm for new ones even if they look good.
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flak monkey
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| posted on 23/1/07 at 08:24 PM |
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Rotor arm and cap are both brand new.
Dizzy is a reconditioned and modified bosch unit with an aftermarket electronic ignition amp added by H&H. No servo, carbs were both fully
stripped and cleaned before fitting, so shouldnt be any dirt, but can easily check.
James, not sure at the mo as not really had chance to drive it properly.
Whats the solution if the compressions are different?! I dont know as i havent checked them. The engine has all new rings and bearings etc.
Sera
http://www.motosera.com
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novacaine
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| posted on 23/1/07 at 08:32 PM |
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what condition is the head gaskget around cyl. No. 4? might be an issue but its likley you would have noticed the side effects before
matt
And you run and you run to catch up with the sun but its sinking, Racing around to come up behind you again, the sun is the same in a relative way but
your older, shorter of breath and one day closer to death
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flak monkey
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| posted on 23/1/07 at 08:37 PM |
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quote:
Originally posted by hicost
Are you just getting this misfire / spit when you rev it or drive it?
Just rev it, not given it enough stick on the road yet... now you are going to tell me its normal arent you?
Engine is completely rebuilt, brand new wear parts/gaskets etc everywhere.
[Edited on 23/1/07 by flak monkey]
Sera
http://www.motosera.com
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TPG
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| posted on 23/1/07 at 09:14 PM |
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Leads.Use one of those house hold spray cleaner things(Flash/Plant spray etc).Fill it with water.Dark garage and mist water over the HT leads. while
its running.You'll see the tracking IF its there.Hope this helps
..Which was nice..
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flak monkey
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| posted on 23/1/07 at 09:21 PM |
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Thanks for all the info gents, very helpful as always! 
Just did a bit of digging via google, and apparently it can be down to a lean mixture on that cylinder as well. Will give it a tweak if necessary.
Think some more tweaking is in order...
Sera
http://www.motosera.com
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