Sooty Plugs

[Blokko]

Developed a misfire under load on my 1.8k. Came to change the plugs and noted that the plug heads (i.e the bit that connects to the HT leads) on cylinders 2 and 3 were sooty.

 

Does this indicate an issue with the HT leads?

[Jonathan Kay]

Is it soot, which can be caused by arcing at a poor connection, or could it be grease?

 

Clean the terminals and the caps. Inspect the inside of the caps. Refit. Do they feel good and all the same as they engage?

 

Does it run better now?

 

Question for the experts: Do you recommend appropriate grease in plug caps, please?

 

Jonathan

 

Edited by - Jonathan Kay on 12 Jul 2014 15:01:31

[Paul Deslandes]

I suspect grease in areas such as this are a bit of a two edged sword. On the one hand it can help keep the connection dry but can also retain and build up dust/contamination which might eventually cause breakdown problems. I would make sure that they are kept dry by a cover and/or sealed plug caps and only use a smear of any grease, e.g. Vaseline, to help the seal to seat properly.

[BSA]

Check the injector loom, Over time the connector wires and joins get brittle let the car run and one at a time wiggle the wires you will immediately hear a miss fire if you have a faulty connection

 

Edited by - BSA on 14 Jul 2014 09:53:59

[ECR]

With deep seated plugs (VX, K, Zetec, etc) I now use silicone spray on the rubber fins of the plug cap. This allows the plug cap to reach and locate with the plug top much more easily.

I have had recent occasion where plug leads on a Zetec felt that they were pushed home but due to the dryness of the alloy head and the stickiness of the rubber weren't engaged. I keep the plug/lead interface dry