What do these spark plugs tell you?

chaos19810 · Post by **chaos19810** » 06/08/13 19:33

Changed my dizzy, rotor, leads and spark plugs I'm no good at reading what spark plugs say so what do they tell the Jedi masters of reading plug

Number 1

Number 2

Number 3

Number 4

I think I may of found the reason for my hesitation?

jimi · Post by **jimi** » 06/08/13 20:36

You need to take the pics so we can see the tip and electrode insulator. Looking at the threads tells you nothing

fingers99 · Post by **fingers99** » 06/08/13 21:20

My guess, someone dropped plug #1! Or didn't use a proper plug socket............

_Al_ · Post by **_Al_** » 06/08/13 22:25

As Jimi says we need to see the electrode and tip, but from what little is on show I'd say that No 1 is not firing right. Did it get broken taking it out or was it already like that?

fingers99 · Post by **fingers99** » 06/08/13 23:49

Just spotted number 3, too!

Strange, methinks, that all have significant rust stains on them. Rapid heating and cooling (by water) will do that, and cause cracking, or maybe they have the spark plug equivalent of concrete cancer?

The firing ends of all that can be seen look OK, but unless you do a plug chop (easy on motorcycles with a kill switch) plug reading is pretty pointless: it'll generally only point out huge issues or tell you about the state of play at the moment the engine was switched off. Of course, the only place it's remotely safe to do a plug chop with most cars is on a rolling road, which is likely to have far better diagnostic tools than the Mk1 human eyeball (and the Mk1 at a distance, too).

jimi · Post by **jimi** » 07/08/13 3:19

fingers99 wrote: that all have significant rust stains on them.

Badly fitting plug leads allowing water into the plug wells will cause that

jimi · Post by **jimi** » 07/08/13 3:21

jimi wrote:
fingers99 wrote: that all have significant rust stains on them.

Badly fitting plug leads allowing water into the plug wells will cause that

MR2DI4 · Post by **MR2DI4** » 07/08/13 6:27

My origional plugs had that brown stain round them and I have not had it since but I think thats because the plugs were really, really old.

dawesy · Post by **dawesy** » 07/08/13 10:24

Nice chart jimi.

shinny · Post by **shinny** » 07/08/13 10:37

fingers99 wrote:My guess, someone dropped plug #1! Or didn't use a proper plug socket............

You know my immediate worry... where did that bit of broken ceramic go?

It probably was lost a long time ago, but if it were in the spark plug well when you removed the plug, is it possible it fell into the cylinder

(If you've run the car since then you already know the answer to that)

chaos19810 · Post by **chaos19810** » 07/08/13 18:27

I noticed it before I pulled them out so I use a section of vac hose and sucked them up! After that I continued sucking until i got all the little bits up it wasn't plesent but it did the job!! I've never seen two cracked plugs in a car before but they are completely the wrong plugs for a mr2 but they do fit a 1.4 fiesta??

fingers99 · Post by **fingers99** » 07/08/13 20:19

I'd suspect they're too hot, at least.

People do the strangest things.

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