Mud-club

Vehicle & Technical => Range Rover => Topic started by: oakeedokee on January 29, 2005, 20:58:56

Title: sooty plugs
Post by: oakeedokee on January 29, 2005, 20:58:56

Took my spark plugs out today - and they were all black and sooty. Does this mean my mixture's wrong?

Title: sooty plugs
Post by: Range Rover Blues on January 29, 2005, 22:19:46

V8s are a sod for sooty plugs if you let them idle a lot, often the plugs need changing prematurely.  A sooty plug can denote a rich mixture, too much choke or a cold engine.  A wetish black plug is excessive oil consumption.

Title: sooty plugs
Post by: oakeedokee on January 29, 2005, 22:45:10

Well they're not wet, so that's good. It has been idling a lot just lately. Perhaps I should clean them up, give it a good run and then re-check before I go tinkering with the mixture.

Title: sooty plugs
Post by: muddyweb on January 30, 2005, 08:29:17

That would be the best bet IMHO.

Are you on carbs or EFi ?

Title: sooty plugs
Post by: oakeedokee on January 30, 2005, 09:48:06

Its a 3.5Efi

Title: sooty plugs
Post by: Range Rover Blues on January 30, 2005, 19:24:09

Another thing worth mentioning is that modern, low lead low sulphur petrol doesn't leave the same deposits as most manuals describe.  When I first started motoring you could tell your car was well tuned by the colour of the exhaust! after a long run of course, now they are never anything but black.

Title: sooty plugs
Post by: oakeedokee on January 30, 2005, 19:59:30

Actually you've just raised another point there. I've only had my Rangie a couple of weeks and was told it takes unleaded. Is that right or should I be alternating with LRP every so often. It's an '89 engine apparently.

Title: sooty plugs
Post by: Range Rover Blues on January 30, 2005, 21:02:29

Unleaded should be fine, as it has hardened valve seats in the Ali head.  You may want to retard the timing slightly from 6 deg though!