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  • 2005 - 2014 S-197 Mustang -General/Talk-
  • 2005 - 2014 Specific V6 Tech

What is running lean mean??

  • Thread starter Thread starter Cobnial
  • Start date Start date Dec 1, 2010
C

Cobnial

New Member
Nov 22, 2010
28
0
0
Santa Clarita, California
Dec 1, 2010
#1
  • Dec 1, 2010
  • #1
So im kind of new at this stuff. I looking at a lot of posts about tuner and cai and basically i came across one that says that having a cold air intake without a tune can make your car too lean? I have a K&N Fipk CAI and an axleback exhaust from AM. Im sorry that it might be a really dumb to most of you guys but can somebody explain if im running too lean? Also, how can i tell? is there a difference in the way my car runs? gas milage maybe? Ive had this set up for months now without a tune. Did i possibly damaged my car without even knowing it? Thank you so much. and again I really have no idea what this stuff means
 
W

Wrxified

New Member
Nov 14, 2010
3
0
0
West Michigan
Dec 1, 2010
#2
  • Dec 1, 2010
  • #2
Running lean simply means your ratio of gas to oxygen is to little. Running rich means your ratio of gas to oxygen is too high. So you'll see ratios like 12:1. This means 12 parts gas, 1 part oxygen.

As you add oxygen and take away fuel, you build energy, combustion increases, heat increases etc. Up to a critical point where you're making maximum power at a safe level. Once you get too lean, too hot etc, you start to run into detonation and start to destroy your motor.

It's a fine line. As you increase your intake of air, you create more power. Manufacturers tune in the rich side to be safe.
 
C

Cobnial

New Member
Nov 22, 2010
28
0
0
Santa Clarita, California
Dec 1, 2010
#3
  • Dec 1, 2010
  • #3
Wow that gets me really motivated to buy that sct tuner now.

thank you
 

ej95cobra

Member
Oct 26, 2003
82
0
6
Southeastern PA
Dec 23, 2010
#4
  • Dec 23, 2010
  • #4
Just a quick clarification, the ratio is reported as air to fuel (not fuel to air as suggested above). A ratio of 14.7:1 is stoich and means the engine is receiving 14.7 parts air to 1 part fuel. Anything higher than 14.7:1 would be lean (not enough fuel being delivered leading to a lean condition and higher combustion temps); lower than 14.7 would be considered rich. Simply adding a CAI and exhaust won't affect the AFR that much. Additionally, your O2 sensors would adjust the fuel impulse if needed.
 
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