Fuel economy and spark plug gaps

[immortality]

Plug gaps made a difference on my old VN (n/a). Maybe the tuning effects things as well? Sequential injection may also have an effect as you are only putting fuel into the cylinder requiring it rather than the batch fire of the older 3800 V6 engines which probably doesn't have the same fuel atomisation as well as having fuel waiting in the port. Hell, The1's ecotec probably runs a lot different to how they came from the factory.

[The1]

yeh possibly, rockers with intake and exhaust would breath a bit better and cooler than stock.

[The1]

ok well ive been running 1.6mm gap for a few months, tune dialed in, currently averaging 10L/100, picture of the current stock plugs gapped at 1.6mm below for all you plug guys to critique, ive now gapped them all to 0.8mm and we'l see how it affects it.

[delcowizzid]

Plugs done melted centre electrode and looks like detonated a lot melted alloy stuck on it

[vlad01]

looks normal to me.

[immortality]

What a dirty spark plug. Mine have never looked like that.

EFI spark plugs are very hard to read because the PCM does stuff like lean burn which cleans the plugs.

[The1]

ive currently tuned it via knock ears, afr's good, no lean cruise, ive found little benefit, from all the sites ive read the reddish tan is what you should have and change in color to half way mark on the strap means heat range is correct. But yeh only what ive read.

[vlad01]

The red/brown ash looking stuff i believe is just deposits from additives in the fuel ( cleaner with 98, ashy with 95 and 91). All mine look more or less like that, also gets deposits if they have been in the engine long time (50k +)

I'll post a pick later of some 2nd hand bosch ones I was trying. probably got more than 100k on it.

[The1]

Plugs have 15k on them, i usually replace them every 20k, using 98 united fuel.

Might pull a plug again tonight after todays run to see if there's a change.

[immortality]

My understanding is that the earth strap shows timing and the heat discolouration on the body how hot (or cold) the plug is running, my understanding is a couple of threads down the body is ideal ( in that pic the heat discolouration is showing on the 4th and a little of the 5th thread).

Fairly much all of my spark plugs come out looking almost new. The ceramic insulator is very clean/white. Fairly much the same with 91 and 95 over the years (would suggest lean WOT).

To me, that plug suggests lean and is running fairly hot too.

This link shows the various different things to look for http://www.4secondsflat.com/Spark_plug_reading.html