Intermintate misfire

[Llewellyn]

My car is suffering from a misfire that comes and goes as and when it pleases.
It has not been used that much after the last two months.

I've cleaned up most of the plugs to the sensors various, and popped a bit of wd 40 on them.
The dizzy looks spot on.
What is my first port of call regarding replacing sensors etc

Cheers guys

James

[sidecarphil]

i would change the Leads , plugs , cap and rotor arm

then look into it further if that doesn't fix it

think it will though 

[Ben Lessani]

Misfire or backfire, or misfire then exhaust backfire or misfire then intake backfire?

Its either missing a spark, or missing fuel. When its missing a spark, depending on the length of the misfire, you tend to get a backfire in the exhaust - which would imply leads, rotor or dizzy cap (as above).

A backfire in the intake tends to be the a wet dizzy cap.

Mine will misfire every 100 miles or so, just once and a quick blip at that, because my dizzy is near the end of its life.

[Llewellyn]

Its got worse, its now really rough on idle, and only one throttle position can be used so it doesnt missfire

[Ben Lessani]

Digi or K-Jet.

Does it do it when warm and when cold?

[Horney]

It's a Digi. I'm telling you James get a fresh set of OE leads on it.

nick

[Llewellyn]

warm and cold.

Roger that Nicholas

[Ben Lessani]

http://www.autostalk.com/cars-maintenance/re-mk2-golf-gti-intermittent-419904.html

Pull the plug leads off one at a time with the engine running, the one that
makes no difference (and will probably send an interesting shiver up your
arm) will be the cause. Replace the leads, it's about £22 for a set from
GSF.

Not that I trust that method, spark plug shocks *tingle*. But worth a try I guess. Get some duck oil in the dizzy, HT connectors and spark plug head (the bit that comes into contact with the HT lead). And repeat on the LT lead too.

[DarnPB]

It does not matter if it is backfiring through the exhaust or the inlet. It depends on a number of things. Timing could be advanced or retarded. If the leads are cracking off against each other, then that 'lost' spark goes somewhere, possibly to the wrong plug!
As mentioned before, replace your leads for OE or uprated replacements. Old leads go porous and will start arching against each other during colder and damper atmospheres. And spraying WD40 only hinders the problem.

[maxp]

i would change the Leads , plugs , cap and rotor arm

then look into it further if that doesn't fix it

think it will though 

Have a digi 8v, mine misfired in idle, and generally everywhere on the rev range. I changed these and it fixed the problem. Took a few hours but was worth it.

If that doesnt maybe check the coil altho they usually last for ages