ok so i just learned this method a few weeks ago and i would like to get a more indepth discussion about this topic.

I have a 12.2:1 compression h23vtec with a stock head and ignition timing is very critical with high compression motors. With Crome, you cant ever really be sure about what the ignition timing is really doing. I havent setup eCtune yet, but i have the program and the license and have been reading on the forum.
I found this video by burgarmas:
http://www.youtube.com/watch?v...=user

around a minute into the video, he explains the procedure for reading the plugs on the turbo motor that he was tuning. I had never really payed attention to the ground strap on the spark plug until after I have watched the video.

So i went to the dyno and did the same method with my motor, i really wish crome had individual cylinder tuning for ignition timing..btw...lol.
I made a pull to 7500 and shut the engine down. The ground strap was burnt to just before the apex in the strap. So i added a couple degrees of timing, made another pull and shut the engine down. Now, the ground strap had burned to the middle of the apex. I decided to add half a degree to get the burn just beyond the middle of the apex. Made another pull and the plugs came out perfect besides #2 which was burned a little farther than the other three. Added another half degree and made a pull. Now, the #2 plug showed slight signs of detonation on the porcelain. This last pull made a tad less power and it showed tiny signs of detonation so i pulled out a full degree. made another pull and the plugs were about where i wanted them and little retarded to safeguard against a bad tank of gas.

Now, with the discussion. Is ground strap reading the only way to determine optimal ignition timing other than reading the dyno? What other tips to spark plug reading do you other experienced tuners have?
Is it just coincidence that having the ground strap burn in the middle of the apex made the most power or is there fact being this?

I'm tuning a 13:1 lsvtec tomorrow with a skunk2 head and i'm planning on using the same procedure on his motor as i did with mine.

 

I know you guys have spark plug knowledge. If you didn't know about reading spark plugs, you prolly wouldnt have gotten as far as you have now

 

I'm in this to learn, but I did a little search and found these two links.

http://www.4secondsflat.com/Sp....html
^^ This having some nice information.

http://www.dragstuff.com/techa....html
^^ this explaining the ground strap.

Maybe this exerpt can answer a question:

Reading For Ignition Timing

Ignition timing is directly responsible for the heat in the combustion chamber and therefore the color of the plug’s ground strap and the color of the first few threads on the outside of the plug. The ignition timing can be checked by looking at the color of the plug’s ground strap and the position of the "blue line" on the strap. The blue line really indicates the point at which the strap has reached annealing temperature of the metal. To help to understand this think of a bar of steel (ground strap) on a table that is being super heated with a acetylene torch at one of the tip ends. As the end heats up and the heat starts moving down the bar you will see a blue line across the bar at some point down the bar away from tip with the torch. This blue line reflects the temperature that is the annealing point of the metal. As the temperature increases the blue line moves further down the bar away from the torch. Similarly, the blue line moves down the spark plug ground strap as you put more heat in the engine.

If you are using a gold colored ground strap like with an NGK spark plug then not enough timing will show the ground strap as still gold or going light gray maybe with a few bubbles on it after a run. As you advance the ignition and put heat in the engine the plug ground strap will turn darker gray as well as the metal at the end of the threaded area. As the metal turns medium to dark gray you should start looking for the blue line (band) around the ground strap. Ideally, you want this blue line to be just below where the ground strap makes the sharp bend and above the weld. If you advance the ignition too far the blue will disappear off the strap and the strap will pick up rainbow colors (blues and greens). The next step beyond that is to start melting the strap from the tip end and detonation. When you are close to the correct timing then only change the timing by one degree at a time. If you ignition system has the capability of adjusting the timing of each cylinder independently (ICT) then you can use that feature to have the blue line in the same position on all the plugs. First, adjust the basic timing to get as many of the plugs to have the blue line just at the sharp bend in the strap. Now adjust the ICT to move the blue line to the same point on the remaining plugs. Once all the plugs read the same you can advance the ignition a little at a time to put the blue line just above the weld on the strap or whatever point gives you the best performance.
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So I guess placing it in the middle gives it the optimum range. Too much heat (further down the strap) would make it show signs of pre-ignition, and not enough heat(closer to the spark) is fouling (which is probably not good either since it won't combust the koolaid very well) . I'm assuming you know this already though but at least I'm learning .

NGK says advancing ignition timing by 10° causes tip temperature to increase by approx. 70°-100° C. Very interesting.

I think this picture may explain why you made the most power in the middle: its the spark plugs optimum operating range.



And I don't think there is any other way you can determine the best timing besides these two since the sparkplug is there in the CC, it's the only thing you can take out from the combustion chamber to tell you what's really good in that motor.

 

this is a good read here: http://www.strappe.com/plugs.html

 

I read the whole article, good information.

 

also, if you need a tool to see the fuel ring on the bottom of the porcelain: http://www.drmomotoscope.com/

I bought the small LED one for $25. Works great. Note that the tip of the specula is the focus point, so if you cut some off, the focus point is closer to what you would want to see at the bottom of the plug.

if my sources found out i'm sharing the kung-fu, they'd hang me. hahahaha

 

great article

 

 

What I don't understand about this is that when you shut the car off, you were at or near redline. So what if you were way off at another part of the powerband? How can you possibly discern an entire proper timing/fuel curve from reading the plugs? You have to shut the motor off at every load point or what? Obviously no one does this. I'm surprised no one else has mentioned this. I'm sure other people have thought of it. So reading the plugs comes after tuning for mbt and a/f, right? As in altering the tune or plugs if they tell you something bad is happening?
Someone please say something about this..or I'm going to think plug reading is analogous to tuning with egt vs 02..

 

since the table timing (and sometimes actual timing, depending on engine management) is known, it will give you a basic idea of what is going on inside the chamber.
You could shut the engine down at every rpm/load but thats a little unnecessary. By reading the plugs at say 3500 rpm at 50 and 100% throttle along with 5500 and 7000rpm, you can get a general idea of how much timing the engine can support and set the ignition tables accordingly.

If you dont have access to a dyno or the costumer does not want to pay for dyno tuning, spark plug reading has big advantages.

 

So do you think with a dyno it still does?

 

Even with a dyno its good to check. Like said, the ems's change timing but have an underlying code with the real timing. A load bearing dyno will display whats going on, but pulling the plugs is always a good idea.

 

Just read through the thread and thought I'd add something.

A lot of people don't know that you still need to be running the correct spark plug heat range. You're readings will be incorrect if you're heat range is wrong.

I forgot what the link is, but it shows you how to find the right heat range for each cylinder. I'll try to find that link.

 

yes i was just going to mention that correct heat range plugs play a part in proper plug reading. I usually tell proper heat range by the heat induced 3-4 threads up on the spark plug. I use to do alot of plug reading when tuning and still do, but you need to ensure proper heat range first. I found this out by swapping plugs and noticing timing changes were needed.

Those articles posted would be a good start for someone to read before attempting to read the spark plugs. Also absorb as much information about plug heat ranges as they make more of a differance then you think.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by arc_55 &raquo;</TD></TR><TR><TD CLASS="quote">
Those articles posted would be a good start for someone to read before attempting to read the spark plugs. Also absorb as much information about plug heat ranges as they make more of a differance then you think.</TD></TR></TABLE>
They sure freaking do!

Also, projected vs non projected plugs make a pretty big difference in FI motors, I've found. Every setup is different, which is why it's important to read spark plugs correctly.

Here's the thread I was talking about. Scroll about half way down. It's a post by Bugermass.
http://forum.ectune.com/viewto...rt=60

 

Bugermass FTW.

I have become a spark plug reading fiend since I talked to him. One of the most insightful dudes I have ever met and my local eCtuner.