[Help]: Spark plug reading

[whatdamn]

hey guys,

i've read my text books and online sources, but i still don't know how to read a spark plug properly.

hope you can help me out by explaining when does one need a 'cold' or 'hot' plug.

provided are pics of my current set of plugs which are the (apparently) proton original NGK BK5E. it's been used on my 4G93P putra for i think a little over 100000 km already.

was thinking if current engine mods would force me to go for a colder plug since engine heat should have increased. current engine mods done are:

mivec 60mm TB
GSR intake manifold (have not bored to 60mm yet)
powerzone 4-2-1 exhaust manifold
no catalytic converter. just a 51 mm ID exhaust piping (~ 2 inches ID).

here's some pics for you to digest and hopefully help me out here with some recommendations.

(if pics aren't clear, pls let me know so i can post clearer ones)

 

[whatdamn]

i also suspect that i've got a spark plug problem as at low RPMs say in 1st or 2nd gear (slow moving traffic speed), the car would suddenly lunge forward even when i'm not accelerating. thus causing that jerky sensation.

 

[g88]

why you car also many problem wan...how you take care of it ??? hehehe....

colder spark plug need longer time to warm up. DOHC engine higher compression (hot) so colder plug is better...

 

[whatdamn]

g88,
what to do, 3rd hand car ma. mmm. so i should get a plug that's rated at 6 or 7 (ngk) right?

 

[whatdamn]

ok, i checked the malaysian ngk website and i find it silly that the putra uses a hotter spark plug compared to the colder one used by the satria gti!

i mean, both are 4G93Ps and i don't think a change from MMC to siemens vdo would require a different plug.

for your refference: http://www.ngksparkplugs.com.my/english/index.php?option=com_ponygallery&Itemid=39&func=detail&id=46

a direct copy and paste from that site:

Model: Putra 1.8i 1996~2000

NGK: BK5E

G-Power: BKR5EGP

Iridiu-IX: BKR5EIX

Gap: 0.8


Model: Satria 1.8 GTI 16V 1999~2006

NGK: BKR6E-11

G-Power: BKR6EGP

Iridium-IX: BKR6EIX-11

Gap: 1.1


Wira 1.6XLi, 1.8EXi 1995~ (same as putra spark plug)

Wira 1.6, 1.8 2000~ (same as satria gti spark plug)


could someone explain why?

 

[g88]

Go for BKR6EGP. It's all the same just the heat range is different. From the NGK site you can see it explain about hotter and colder spark plug.

From the pic, your engine seem running very lean, way too "dry"...not so good ler...

 

[khoyos]

well, since u are using heat range 5, then why dont u try using bkr6e-11. cost around rm30 only, worth trying.

for daily driving, i personally prefer original OEM recommended heat range. but for performance driving, cold plug feels slightly more powerful...

 

[whatdamn]

g88,
how do you know if it's too lean? do you look at the build-up of soot? and what should i do if it's too lean?

khoyos,
yup, plan to use back the recommended colder plugs as not only are they cheap, but because any of those 'racing' plugs offer little gains with my current engine setup. also, from what i understand, racing plugs are usually colder and offer a thinner electrode made from a different precious metal. hence the cost.

 

[khoyos]

well, the cold plugs i'm using has exactly same electrode size(well it looks the same) only colder. not so expensive. rm12.50 per piece at motorcycle shop. BPR7ES. 1 step colder than the recommended OEM BPR6ES which cost rm30.

 

[Joeker]

I think your plugs look fine.

When your a/f is lean, the plugs'll be whitish spots and specks.

Yours is brownish with allittle KFC chicken skin look. It look ok.

If its covered in thick layer of carbon dust, its rich.

If its sotty and oily, the piston rings or valve train have gone south.

I think using cold rated plugs on NA engines is an overkill.

Anyway, try seeing a doctor for detail diagnosis.

 

[g88]

hnmm....with 2nd though if its not too lean possible might be "overheat" since u using hotter plug now..

Check out

http://www.gnttype.org/techarea/engine/plugs.html
http://www.ngksparkplugs.com/techinfo/spark_plugs/faq/faqread2.asp
http://www.spark-plugs.co.uk/pages/technical/diagnosis.htm

Well your little 4G93P is kinda of a monster...spark plug play important roles though...part of engine care.

 

[Joeker]

hnmm....with 2nd though if its not too lean possible might be "overheat" since u using hotter plug now..

At such low engine RPM, I doubt the plugs are "overheat".

The problem of plugs overheating are usually caused by hi cylinder pressure predominantly in Variable valved timing and forced fed engines.

 

[malyadayada]

better change ur plugs whatdamn.....
ur plugs totally worn out.......
im using the rm 45 - rm 60 price spark plugs

 

[whatdamn]

joeker,
thanks. i think i'll use the recommended plugs for the satria gti which is a step colder than my current set. although i would like to know why there is a difference in spark plugs used by these two engines.

g88,
thanks for the 1st link. mine looks normal.

malyadayada,
well, 100k km of use, i guess it's time for a change. :P

 

[khoyos]

wow 100k km, i change mine every 2 months, roughly 2-3k km

 

[whatdamn]

khoyos,
i guess i should make it a habit and change it at every oil change (roughly 5000 km)

 

[huakenny]

heat range 6 will be better :_: