mistergrumpy
|
| posted on 10/7/11 at 10:33 AM |
|
|
Emissions And Spark Plugs
Can someone clarify something for me please? The car's up for its first MOT next year and I'm starting to think what could go wrong.
Emissions being the one thing outside of my control for home tinkering really. On SVA I was allowed to turn the mixture screws whilst the car was on
the machine and brought it into line with emissions limits. I haven't altered this mixture since then or altered anything else engine wise.
Now, my car always needs choke to start it which I put down to it sitting for periods of time and this Summer when I taxed it I've started with
an intermitent misfire which eventually sorts itself out after warming up and a bit of revving and popping. It appears to be one of the plugs, but it
looks, appearance wise, the same as the other 3, black and wet. Now this is the question, I assume this is the engine running rich but can the plugs
still be this colour AND the emissions still be within range?
|
|
|
|
|
matt_gsxr
|
| posted on 10/7/11 at 11:01 AM |
|
|
Just get 4 new plugs. I know this is a locost site, but plugs are a service item.
Plug reading is a bit of a black art. For example if it were rich somewhere in the throttle range, then I don't think they would clean
themselves up if you idled for a while. MOT is at idle, so you might be alright.
What emissions level are you required to meet?
|
|
|
big_wasa
|
| posted on 10/7/11 at 11:12 AM |
|
|
When playing with an ecu I was running VERY rich. The plugs where dripping. One of the plugs never worked properly again despite only 3 hours use. I
could get them hot with a blow lamp and they worked for a while.
I just binned them and put more new ones in. About £3 each from Fords. Problem solved.
Once a plug starts to track down the insulator there buggered.
[Edited on 10/7/11 by big_wasa]
|
|
|
coyoteboy
|
| posted on 10/7/11 at 01:41 PM |
|
|
Yup, cheapest easiest thing to replace in the hope of a fix is the humble plug, and at about £2.30 each (there's rarely a need for iridium
unobtanium alloy ones) they can be considered an annual service item.
|
|
|
mistergrumpy
|
| posted on 10/7/11 at 04:35 PM |
|
|
Yes certainly I'll replace the plugs that what I was doing yesterday when I went to Halfords but they told me that if they weren't on the
shelf they didn't have any. I asked them to look in the under shelf storage but they told me they were empty. I had already had a quick peek in
there after being told a few weeks ago they didn't even sell motorbike plugs, even though I pointed at them.
My query was is it possible to have black wet plugs but still be within emissions range? I'll dig out my SVA emissions results after my tea 
|
|
|
mad-butcher
|
| posted on 10/7/11 at 06:31 PM |
|
|
Hi Chris.
Is the clutch still working OK. When you say black & wet, do you mean sooty black and fuel wet or oily black and oily wet. Rough guide Sooty
Black = Rich, Oily Black = Rings or guides, White = Weak, Light Choclate Brown=you've got it bang on.
I'm a strong believer in the old fashioned plug chop to read plugs, but you need co-ordination a kill switch and of course a plug spanner.
Find a nice quiet stretch of motorway take it up to peak revs in tops gear, now the bit that needs the co-ordination, kill the engine and dip the
clutch both at the same time and coast onto hard shoulder and check the plugs, idealy you're looking for is a chocolate brown centre.
tony
|
|
|
mistergrumpy
|
| posted on 10/7/11 at 06:57 PM |
|
|
Clutch is holding out thanks.
I'd have to say sooty black I think. I have replaced the valves guides not too many miles ago and I may have done the rings or at least some of
them I can't remember.
I have a feeling they're going like this because the car's sitting too long basically without use but what with work, weather and building
up the confidence to take it out more often it doesn't.
I don't know for sure whether the plug condition is a result of this only though or whether it's the mixture and thus emissions.
When you say look for a brown centre, which centre am I looking at? The electrode?
Oh thanks so far.
[Edited on 10/7/11 by mistergrumpy]
|
|
|
britishtrident
|
| posted on 10/7/11 at 07:48 PM |
|
|
Sounds flooding --- float chambers are getting over filled, check the fuel pump output pressure is within spec for the carbs.
|
|
|
mistergrumpy
|
| posted on 10/7/11 at 09:11 PM |
|
|
Something like that had crossed my mind. The pump is the oem part thats comes with the engine.
I'd like to get it to a rolling road or the likes it's just time as ever.
|
|
|
mistergrumpy
|
| posted on 11/7/11 at 09:44 AM |
|
|
I reckon I may have found my answer. I was doing a lot of reading last night and came across a PDF off NGK's website on 20 Q&A's which
was really helpful. It can be downloaded here if anyone is interested. Basically put the
spark plug has to reach temperatures of around 450 degrees before it will start burning the soot off itself and prolonged low speeds or short journeys
will cause the plugs to foul up and misfire. I don't really live near any country roads and never really stray too far before breaking down!
Coupled with crappy working hours and a washout Summer I reckon that now I've addressed my clutch problem and rejigged my steering and
suspension I need to take it out for higher speed blats and get the plugs up to temperature rather than just pootling.
|
|
|
G.Man
|
| posted on 11/7/11 at 10:24 AM |
|
|
Yeah bikes need a good ass whooping to get the plugs to operating temp, and you can only read them properly after a proper warm up, and a top gear
full throttle plug chop, which you are unlikely to manage on the road (dyno needed).
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
|
|
|
