Hallo,

just to confirm my own experiences, here are some thoughts about reading Plugs correctly.

We all know that we only can make a valid statement of whats going on in the combustion chamber by reading the plugs after we shut off the engine at the desired situation (i.e. Full-Throttle right befor/at or after peak tourqe rpm).

My open qustion on this is: How long did you let the engine operate at the desired situation befor shut it off and pull the plugs?
When i do my runs, i make a 2nd or 3rd gear run and pull the plugs as described but never see any signs of knock and nearly all plugs are showing a lean mixture but my wideband shows a 11.2:1 AFR which is definitive not lean ;-) so my thoughts are about this, that i maybe have not enough time to build a "picture" on the plugs?!?

Second thing is, is there somewhere a GOOD plug reading (with pictures) website for injection engines ... i found many but they are all for carburators and the description of what to look for seems to be a bit different from what we need.

Maybe this thread gives a basis for a good discussion about this topic... i know that there where many other "how to read plugs" threads, but the above mentiond topics aren't discoverts until now i think...

Best regards
Malte.

 

Up, It would be nice to have a definitive thread on correctly reading plugs.

 

here's a link that i've had forever.........i may have gotten it off honda-tech, but i honestly dont remember. hope it helps a little:

http://www.4secondsflat.com/Sp....html

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JSpin &raquo;</TD></TR><TR><TD CLASS="quote">here's a link that i've had forever.........i may have gotten it off honda-tech, but i honestly dont remember. hope it helps a little:

http://www.4secondsflat.com/Sp....html</TD></TR></TABLE>

i know that site... i saw it on H-T earlier... do you sure that the stuff is not for carburators? i know that it is nearly identical but i think there are some small differences from reading some things or am i wrong?

but until now i think it is the best "Plug reading" site i found.

 

i hope we can find a good one.. i need to tune a 289ci V8 with a holset hx40 on it.. no wideband or EGT!..

 

obviously a carb'd motor is a different animal.......but i think for people are just beggining to read plugs, it offers some interesting tricks: timing marks, etc

 

Reading plugs IMO does no good unless reading for detonation.
If you have been running on plugs for a while and pull them and are rich, they will be black. If they are burning good they will be tanish. If they are new they wont show a burn really at all until they get miles on them.

Now if you have olderplugs that are already black and try and do a WOT pull, it wont show you anything but black plugs because they were black before.
New plugs same deal. it wont show you anything yet, because it takes a while for them to change color.
If you have tan plugs and do a WOT run and your tune just all the sudden became off, you might see a little diff, but they wont just turn black that easy.
So its not really a good way to tell anything. unless you look at the long haul. But even thats sketchy.

Do it the old fashioned way. Wideband and maybe by smell of fuel.

 

a very good point.......maybe you could answer this for me. it might just be my imagination, but seems like motors running on race gas exhibit what you described even more so. i looked at the plugs from a friends motor that he'd been running throughout the day and they looked almost brand new. maybe it was just running a little better than most motors, err...........bah, whatever, i'm rambling

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itr206 &raquo;</TD></TR><TR><TD CLASS="quote">Do it the old fashioned way</TD></TR></TABLE>

The old fashioned way is reading plugs

 

if i'm reading my plugs,
I'll do arun, usually 1-2-3, and shut it off at the top of 3rd, right when i let off the gas
(yes at like 7000rpm I turn off the engine)
then coast to the side of the road and pull the plugs to look at them.

 

This article is much better
http://www.maxracesoftware.com/spark_plugs.htm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DRAGLS &raquo;</TD></TR><TR><TD CLASS="quote">This article is much better
http://www.maxracesoftware.com/spark_plugs.htm</TD></TR></TABLE>

same one i learned off

 

Hi,

so i read both above mentioned articles in detail and found some differences:

part of the plug / 4secondsflat article / maxrace article
ground strap / timing indicator / heat range indicator
base ring / idle mixture / afr
porcelain / afr for idle,cruise and WOT / indication for detonation
threads of plug / heat range indicator / nothing mentioned

so what do you think about this... which one is right?

but i think both are a bit carburator related because both mentioned "jetting" which for me seems to be carb related stuff...

Best regards
Malte.

 

by the way... has someone a picture of a NEW Plug after a 1-2-3-shutoff run with light knock?

i think i'am not the only one who want to know how the often described black or brown specs are realy look like...

Thanks
Malte.

 

just to bring the topic up again...

 

bump