Reading Spark Plugs- lean condition
Thread Starter
Racer
Joined: Jul 2004
Posts: 470
Likes: 8
From: Northwest Washington
Reading Spark Plugs- lean condition
I just put Dynatech Supermax headers on last weekend and noticed my old plugs were grayish/white (45,000miles) which indicates a lean condition. I have heard adding the headers to a stock LS1 will make it run lean. My plan is to put several hundred miles on and check the plugs again. If still light gray/white, find a tuner and reset lean/rich mixture. Any advice?
Burning Brakes
Joined: Apr 2003
Posts: 1,140
Likes: 0
From: GOCC - Rebels Without A Clue Santa Barbara, CA
IMHO, If you can afford it, It's always best to get a tune after headers in order to get the full amount out of them. Plus you will most likely get better fuel milage from a tune. I went from 27 MPH highway to 31 after my tune and the throttle response is much better than before. Also I wouldn't bet on ash coloring on plugs as a lean condition. Fuel additives in gasoline can do that. If your not getting lean codes then you may not be lean. Mine went rich with the header install. 
Thread Starter
Racer
Joined: Jul 2004
Posts: 470
Likes: 8
From: Northwest Washington
Originally Posted by Threed
IMHO, If you can afford it, It's always best to get a tune after headers in order to get the full amount out of them. Plus you will most likely get better fuel milage from a tune. I went from 27 MPH highway to 31 after my tune and the throttle response is much better than before. Also I wouldn't bet on ash coloring on plugs as a lean condition. Fuel additives in gasoline can do that. If your not getting lean codes then you may not be lean. Mine went rich with the header install.
Thread Starter
Racer
Joined: Jul 2004
Posts: 470
Likes: 8
From: Northwest Washington
Originally Posted by TT_Vert
.you need to read the plugs after a WOT blast and shutdown. What you are seeing is lean (14.7:1) but perfectly normal BTW, i was way rich w/ the dynatech headers (11.5:1)
Dave
Dave
Thanks!
Le Mans Master
Joined: Oct 2003
Posts: 6,126
Likes: 19
From: Streamwood illinois
14.7:1 is stoichiometric (what the EPA wants these cars to run at and what the computer strives for). 11.5 was what my wideband said my AFR was at WOT w/ the long tubes. Im at 14.7 at idle regardless of mods. The problem is the sensors are further down stream so they might not be as accurate.
Dave.
Dave.
