Intermittent Misfire (Not Just 1 Cylinder)

[joni 0]

Hi All,

I’ve recently got my 205 Gti back on the road after a 5 year period of largely not being moved. I drove it for a few weeks in October then haven’t driven it since until the past couple of days. I now have an intermittent mis-fire. I can’t think of anything I could have done to cause this in terms of maintenance. It’s only just started but it’s not just 1 cylinder, it feels like it could be all cylinders at points.

It hasn’t completely stopped on me and at some points it’s quite happy to go through the rev range. So far it seems to be when I accelerate quickly that it happens and it stutters (not in a consistent way) to go up through the revs. So my thoughts initially are fuel or spark?

Fuel

The tank is low but not unusually. Sometimes it revs completely normally so I suspect this is not a fuel related problem.

Spark

I think when it happens it affects all cylinders, not just 1 so I suspect it’s not a spark plug or HT lead. It could be the coil, the lead from the coil or the distributor / cap / rotor arm? I don’t think all power goes when it happens but I’ll know shortly when I drive home if the lights go off at the same time!!!

Any thoughts where to start first on diagnosing this one? I have a rally a week on Saturday so need to get the car back to normal ASAP.

[toolie72 67 1 Cars]

Plugs wet when it does it? If so its pointing to no spark rather than no fuel

Mine had random issues like this which would jump from cylinder to cylinder-was leads failing (fell apart when treated roughly)

[Alan77 78 1 Cars]

Old leads broken down and arcing?

[pug_ham 244 3 Cars]

What is the condition of the dizzy cap & rotor arm?

 

I chased a similar hesitancy on a 309 a while ago & went through the usual, discounting the cap & arm because they weren't very old, to find out this was the cause all along.

 

g

[ALEX 98 1 Cars]

Check the condition of the fly lead and connector from the dizzy to the ignition amp,

[Henry Yorke 269 3 Cars]

Airflow meter connection can cause this, often highlighted when the engine moves about. Check the pins haven't got pushed back in the connector too.

[steve@cornwall 100]

If it's the earlier type coil I would suspect corrosion where the king lead goes into the coil, seem to collect condensation and are in a terrible position when topping up the expansion tank