what are my old spark plugs telling me?
- maxgreenwood
- BXpert
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what are my old spark plugs telling me?
Sorry for slightly blurred pic. They came out in this order looking at engine from front of car. Left and right-most were quite white - weak mixture? Middle two are quite carbon-y. They should all at least show the same signs i think?
I don't have any experience with petrol engines, but i would think the carb / distributor is not providing the same mix to each cylinder? It does run a little rough on a steady light throttle, ok when more fuel pumped in. And sometimes loses go for an instant like one cyliner is not sparking or something, but that's a guess as i say with my limited experience.
I have been advised to clean the rotor arm and should i possibly look at a new coil and/or ignition module?
Old spark plugs May 2011 by Maxwell Greenwood, on Flickr
I don't have any experience with petrol engines, but i would think the carb / distributor is not providing the same mix to each cylinder? It does run a little rough on a steady light throttle, ok when more fuel pumped in. And sometimes loses go for an instant like one cyliner is not sparking or something, but that's a guess as i say with my limited experience.
I have been advised to clean the rotor arm and should i possibly look at a new coil and/or ignition module?
Old spark plugs May 2011 by Maxwell Greenwood, on Flickr
'92 16TXS (m), Dark metallic green, 74k
'90 16TZS (m), White, 86k
'89 19TRS auto, Olympic Blue, 133k
'88 Saab 900 8v Turbo (auto) 107k Red with Tan leather, lovely drive and well maintained.
'07 Hyundai Santa Fe 2.2 CRDi 85k (m). Practical family wagon
'90 16TZS (m), White, 86k
'89 19TRS auto, Olympic Blue, 133k
'88 Saab 900 8v Turbo (auto) 107k Red with Tan leather, lovely drive and well maintained.
'07 Hyundai Santa Fe 2.2 CRDi 85k (m). Practical family wagon
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- BXpert
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Mine usually look the same.
I'd say that's fairly normal with a mass-produced inlet manifold built to a price. The two middle cylinders get the best fuel/air charge (the carb's right above them, while the two end cylinders have to make do with whatever they get - and after fuel droplets have fallen out of suspension due to tight bends (the Dyson effect :wink) cold and gravity.
A really weak mixture will show serious signs of plug overheating with bubbling on the ceramic insulator and VERY white deposits.
If the car doesn't stumble or hesitate in use, I'd opine that you don't have a problem there. The plugs are nice and clean too! If you're passing this way I'd be happy to hook my exhaust gas analyser up to your pipe (ooer Nurse!) but I think you'll find it's within tolerances.
:
I'd say that's fairly normal with a mass-produced inlet manifold built to a price. The two middle cylinders get the best fuel/air charge (the carb's right above them, while the two end cylinders have to make do with whatever they get - and after fuel droplets have fallen out of suspension due to tight bends (the Dyson effect :wink) cold and gravity.
A really weak mixture will show serious signs of plug overheating with bubbling on the ceramic insulator and VERY white deposits.
If the car doesn't stumble or hesitate in use, I'd opine that you don't have a problem there. The plugs are nice and clean too! If you're passing this way I'd be happy to hook my exhaust gas analyser up to your pipe (ooer Nurse!) but I think you'll find it's within tolerances.
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- rayfenwick
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The Fleet (most recent first):
2000 Citroën XM 3.0 24V V6 Exclusive Auto (pre-MOT)
1997 Citroën XM 2.0 TCT Exclusive Auto (for sale)
1979 Citroën CX 2.4 EI Cmatic Prestige (slowly being restored)
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as Gibbo says or even valve clearance's,
rotor arm wont give cause plugs to varry in colour between each other,
i would also do a compresion test,
regards malcolm
rotor arm wont give cause plugs to varry in colour between each other,
i would also do a compresion test,
regards malcolm
curent ride
K reg BX 17TD TZD est
also own
K reg D special
no longer have
H reg CX saffari 2.5 TRI (now gone to Malaysia)
R reg xantia 1.9TD est (gone to meet its maker)
K reg BX 17TD TZD est
also own
K reg D special
no longer have
H reg CX saffari 2.5 TRI (now gone to Malaysia)
R reg xantia 1.9TD est (gone to meet its maker)
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- BXpert
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If it was flashover/tracking, would there not be carbon deposition on the ceramic further up near the HT terminal? My experience of tracking is that you get fine black lines where spark erosion has pitted the insulator and deposited carbon - which leads to even more tracking. This is especially evident inside distributor caps where moisture has provided the initial earth leakage path, and carbon deposition has made it permanent - you can see the fine, black, spider-webbed tracks and, often, scraping them away will restore the cap's resistive integrity long enough to get you home.
The discolouration where the plug caps end is, I suggest, nothing more than the oil mist found in most engine compartments baked onto the hot insulators.
The discolouration where the plug caps end is, I suggest, nothing more than the oil mist found in most engine compartments baked onto the hot insulators.
yes Bob but if your porcelain has dirt/oil deposits around the kneck it can lead to/cause tracking, even more so if it becomes damp,
regards malcolm
regards malcolm
curent ride
K reg BX 17TD TZD est
also own
K reg D special
no longer have
H reg CX saffari 2.5 TRI (now gone to Malaysia)
R reg xantia 1.9TD est (gone to meet its maker)
K reg BX 17TD TZD est
also own
K reg D special
no longer have
H reg CX saffari 2.5 TRI (now gone to Malaysia)
R reg xantia 1.9TD est (gone to meet its maker)
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- BXpert
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I agree entirely Malcolm, but that's not what Mister Gibster said.citronut wrote:........yes Bob but if your porcelain has dirt/oil deposits around the kneck it can lead to/cause tracking, even more so if it becomes damp ..........
I agree that those deposits may LEAD to flashover under wet conditions, but they aren't CAUSED by it! HT Arcing leaves distinctive track marks, not bands of simple grime like we see here.the discolouration suggests 'flashover' i.e. the spark when the motor's under load running down the outside of the plug
Same horse, different nosebag?
- maxgreenwood
- BXpert
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- Joined: Wed Aug 15, 2007 9:44 pm
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I have! - and fitted. Very little dicernable difference in running, still got the hesitation / not so smooth running on a steady throttle, i would think the jets need cleaning out? Would some of that cleaner additive like Redex do anything worthwhile? Maybe at a higher concentration than recommended on the bottle? I have some.
'92 16TXS (m), Dark metallic green, 74k
'90 16TZS (m), White, 86k
'89 19TRS auto, Olympic Blue, 133k
'88 Saab 900 8v Turbo (auto) 107k Red with Tan leather, lovely drive and well maintained.
'07 Hyundai Santa Fe 2.2 CRDi 85k (m). Practical family wagon
'90 16TZS (m), White, 86k
'89 19TRS auto, Olympic Blue, 133k
'88 Saab 900 8v Turbo (auto) 107k Red with Tan leather, lovely drive and well maintained.
'07 Hyundai Santa Fe 2.2 CRDi 85k (m). Practical family wagon
- Tim Leech
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I would undo the airfilter pipe from the top of the carb, one hex screw and a jublilee clip, pull it off and spray carb cleaner directly in with the car running, dont over do it though or it may stall, ideall I would keep the revs up whilst you do it.
Is the hesitation there all the time or just when its warm, could be that someones fiddled with the mixture and made it run too lean, my 16TRS was like that, it flew through the MOT but they did say it wa running on air! so I tweaked it up a bit as it was rather flat.
Is the hesitation there all the time or just when its warm, could be that someones fiddled with the mixture and made it run too lean, my 16TRS was like that, it flew through the MOT but they did say it wa running on air! so I tweaked it up a bit as it was rather flat.
Lots of Motors, mostly semi broken....