yellowish spark plugs

[matt87]

hey guys i noticed my car starting to break up a bit on the top end so i pulled my plugs to see how they looked. they all had a yellowish crust on them. my car has seen a steady diet of mosly c-16 and lots of boost, 25 psi. my performance has dissolved as of recent and i was thinking maybe they are the wrong heat range or fouled. they are autolite 103's. the car dynoed 4 months ago and was a beast but now it can hardly keep pace with the other car in my sig in street tune.

 

[Chuck Leeper]

Crusty??

My plugs do that also, if run too long. would suggest you make FREQUENT visits to use the info for tuning. race gas has ingredients that will make doo doo if run too long. I change mine everytime I go to the track, especially if I've been out for some cruizin' and got more than 250 miles on them.

 

[d0n_3d]

you should dump the autolites and throw in some ac delco cr43ts plugs gapped at a tight .035"

you might also try the cooler plugs which are the cr42ts but if your car misses with those then definitely use the 43's...

also yellow plugs means detonation and that is not good...black means you are running too rich...like mentioned i would change the plugs like every 3 months since they are cheap and very easy to do on these cars...i do it for insurance

 

[matt87]

thanks for the tips. Don, i never get detonation with c-16 so i dont think thats an issue. the plugs do have about 1500 miles on them so i guess its time to change. so could old plugs cause the miss and general loss of power??? also i thought 42s were better for high boost operation??

 

[Steve Wood]

Don, first he has GN1s and cannot use the plugs you suggested. Also, Autolites are outstanding plugs and compare fully with ACs. Some of us think they are better.

The plugs are simply fouled with lead and other stuff and need to be replaced routinely when fed a diet of leaded race gas. The deposits will cause hot spots and detonation/preignition.

 

[d0n_3d]

oops! my bad...it was late and i forgot to read the sig...hehe shows my youth

 

[bruce]

Originally posted by matt87
hey guys i noticed my car starting to break up a bit on the top end so i pulled my plugs to see how they looked. they all had a yellowish crust on them. my car has seen a steady diet of mosly c-16 and lots of boost, 25 psi. my performance has dissolved as of recent and i was thinking maybe they are the wrong heat range or fouled. they are autolite 103's. the car dynoed 4 months ago and was a beast but now it can hardly keep pace with the other car in my sig in street tune.

High speed Glazing.

Too hot of plug, in combination with too much fuel, and prolly too much timing. Replace plugs with a range cooler, first. Then try backing off the tune a lil.

Often dyno Tunes wind up that way. ie too much timing.