bump for more info. After speaking with cobra through pm's he just told me he experienced a big loss in power and rich afr's after pulling back enough timing so the plugs would show no knock. What could be making his car look like there is knock on the plugs when he is retarded so far from mbt? It isn't running the kind of boost level that would require race gas or anything. Maybe something is lowering his octane like oil in the combustion chamber?

 

I was quite interested in the plug reading thing myself and I was talking an exprienced engine builder (20+ years) and he informed me that you cant base all your tuning off the plugs. He told me that it was helpful, but a wideband EGT and knock sensor on a dyno is the most ideal conditions to tune an engine with... So I kinda figured it was an oldschool way of tuning an engine, but Im still interested to learn more about this subject.... Bump for someone who can shed more light on the topic....

Blaze

 

Well i think the interest is more for safety rather than actually tuning the car off of the plugs. Everyone knows that using the dyno and wideband is the best way to tune, but the most accurate way to tell if you are knocking is to check the plugs. Even knock sensors can show false knock quite often. We just need an accurate way to check for detonation.

 

good post.

 

 

hey, lets bump this up...im still curious as to why he is knocking?

 

Ill post pics of my plugs tomorrow or friday. Right now I have a big physics mid-term tomorrow that I need to study for.

 

small pc.'s of allum. are definaly something to look into. Maybe the ground strap is too close to the piston face?

I switched from a taller #7 ngk plug to a #7 ngk that sat closer to the base. This seem'd to of solved my alluminum specing from occuring.

Maybe fuel quality can play a role too? Tempature change?

With a cold day, you not only have lower IAT's, but your oil temps stay a tad cooler and your fuel tempature is colder. Cold and Warm gas will atomize differntly.

just throwin things out there...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDMs1eeper &raquo;</TD></TR><TR><TD CLASS="quote">small pc.'s of allum. are definaly something to look into. Maybe the ground strap is too close to the piston face?

I switched from a taller #7 ngk plug to a #7 ngk that sat closer to the base. This seem'd to of solved my alluminum specing from occuring.

Maybe fuel quality can play a role too? Tempature change?

With a cold day, you not only have lower IAT's, but your oil temps stay a tad cooler and your fuel tempature is colder. Cold and Warm gas will atomize differntly.

just throwin things out there...</TD></TR></TABLE>
I seriously suspect something with those zfr plugs sitting closer to the piston too. Temp change shouldnt play a huge roll unless you have big injectors. The stock correction factors compensate for that. With my 450's i haven't noticed much difference in different weather. I also have my iat sensor in the intake pipe too which i hear seems to keep things more consistent.

 

 

As promised, here is my timing map for the low cam: