this is a strange one.

I have a new engine (less than 2 hours running time)

the drive to the SVA (the first long drive in the car) showed it had developed a misfire. hense it passes the CO2 emissions test easily but failed the Hydrocarbons -1465p/m allowance is 1200 and flakmonkey got under 400 with a similar engine.

on the way home i pulled in and pulled the leads off one at a time to find ths cylinder. then pulled the plug and it was wet and black, the one next to it was ok and looked good. i swapped the plugs and i still had a missfire on the same cylinder.

i bought a device that goes between the plug and the lead and shows if you have a spark, and yes i do on all cylinders. and the engine still runs rough.

what are the most common missfire faults

i can think of
Faulty Plug
Faulty Lead
Faulty Distributor cap.

I did turn the engine over with out the plug and there appeared to be compression.

any ideas????

Help....

Ditch

sorry but what engine is it?? and how old

I think the next thing is compression check. Are you losing any water?

a pinto 2.1 twin 45's

fully rebuilt by vulcan engineering.

total running time 4 hours (inc 100 road miles to and from the SVA)

lumination contactorless ingition system.

i'm not losing any water, the engine is running at 75 to 80 degrees C.

in effect a brand new engine

ditch

[Edited on 6/7/07 by ditchlewis]

Do you have a spark if you put a plug in the offending plug lead and start the engine whilst laying the plug on the head to earth it?

Plug was wet through petrol or oil??

You could try swapping the lead for the offending cylinder with another see if the problem stays or moves cylinders.

Try another cap. Gotta be easier than turning the dizzy 1/4 & re-timing etc lol

I would do a compression check though.

Hi is the tappets set right ?
i had similar problems and it was the carbs not set right ?

Is the dizzy cap ok on cracks ect
Jacko

[Edited on 6/7/07 by jacko]

oh yes, i was holding the plug to the head when i first tried and what a kick.

if the lead touched the head do you think it would short out?

ditch

High HC and wet plug says there's fuel to the cylinder. Swapping the plugs and the miss staying on the same cylinder eliminates the plug. So that leaves...The lead; swap the bad cylinder lead for another one and if things change there's your answer. The dizzy cap; look inside for cracks. Compresion loss; put a tester on and see.

Adrian

the plug is wet but it is not thick enough to be oil.

the tappets i'll check, i did set them after a 30 minute idle some months back.

the carbs are an easy check. i've just bought a colortune and an adaptor for the 18mm plug and i can give that a go.
when i remove the leads from the first 2 cylinders i get a bigger effect than for the back 2. so carbs may be it.


will give it a go tomorrow.

the wife is calling me to bed so i had better go

D


ditch

It sounds like you have a spark, does the plug reek of fuel?

Edit - how can you think of going to bed when you have a problem like this?

Could be overfuelling on that cylinder - the colourtune should indicate or rule that out.

[Edited on 6/7/07 by Mansfield]

Check your valve stem oil seals...

If you have tried all the different combos of spark plugs/leads etc sounds like it could be your carbs.

I've got a 2.1 pinto with twin 45s and seemed like it developed a misfire, turned out the carbs were out of balance.

Definately worth checking the carbs if it seems your getting sparks to all cylinders.

quote:

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Originally posted by Mansfield

Edit - how can you think of going to bed when you have a problem like this?


[Edited on 6/7/07 by Mansfield]

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Could it be a loose jet or accellerator pump valve on that cylinder allowing excess fuel in?
Paul.