Damn thing has started misfiring again, when its cold it runs okay but once its been on the road for about 10mins it starts misfiring.

put new plugs in it last week as one had broken down, however I'm now beginning to suspect ANOTHER coil pack (its already gone through 2 in the past and its only 40k!).

two questions:

if it is a coil pack will both outputs on it go at the same time?

I know you can test the resistance on a coil - but, between which parts? and what should it be in ohms?

Thanks

I have no idea what your Renaults ignition system is like but it will be either like the Ford oens using EDIS, picture below or have a separate coil pack stuck on the saprg plug or some other.

with the Ford like unit, you can measure primary resistanbce between the wires labelled Coil 1/Coil 2 and the wire IGN SW.

for electronic igniton it should be about 1.5 ohm (I can measure mine to confirm) and alseo the ouptu coil between the tow paired ignition lead sockets - no idea what ohmw you shouldget.

but foir sure if any of these if open circuit, the coil pack is fooooooked.

oops, forgot the piccy:



[Edited on 3/4/08 by 02GF74]

With coil packs I find if it gets to the stage of a misfire it is best to change the leads and the plugs and fit only OEM spec plugs

Is a twin spark coil pack with two separate leads or a does the coil sit on top of one plug with lead going to the other ? If the former try a new set of leads if the latter go straight for coil packs, leads and another set of plugs.

I have found this online shop is good for coil pack and leads.

http://www.ignitionleads.co.uk/Mod.aspx?Man=RENAULT

You may find to avoid future it helps to increase coil pack life to reduce the plug gap from the manufacturers recommended figure and in change the plugs earlier than official mileage interval . These days some manufacturers recommend 30,000 or 60,000 mile intervals between plug changes --- I would advise changing even platinum plugs at 20,000 miles.

[Edited on 3/4/08 by britishtrident]

[Edited on 3/4/08 by britishtrident]

thanks for the info guys - tested last night, diagnosed 1 dead. bought a pair earlier so I now have a spare and an OBDII reader so I can reset stuff.