C6 Tech/Performance LS2, LS3, LS7, LS9 Corvette Technical Info, Internal Engine, External Engine, Tech Topics, Basic Tech, Maintenance, How to Remove & Replace
Sponsored by:
Sponsored by:

Can engine run lean?

Thread Tools
 
Search this Thread
 
Old Jan 24, 2012 | 09:31 AM
  #1  
chpdbp's Avatar
chpdbp
Thread Starter
Intermediate
 
Joined: Sep 2011
Posts: 43
Likes: 0
From: Williamsport Pa
Default Can engine run lean?

If you install headers, 102mm intake with throttle body is it possible for the motor to run too lean prior to getting it re tuned? The LS2 has already been tuned, I am just curious as to whether the on board fuel management system will absorb the difference of air coming in and going out and adjust for it. Are larger injectors recommended, say 50lb. for this setup, or not. An help or tips is much appreciated. Thank you.
Reply
Old Jan 24, 2012 | 01:47 PM
  #2  
LS1LT1's Avatar
LS1LT1
Team Owner
25 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2001
Posts: 27,236
Likes: 121
From: Short Hills, NJ
Default

Originally Posted by chpdbp
If you install headers, 102mm intake with throttle body is it possible for the motor to run too lean prior to getting it re tuned? The LS2 has already been tuned, I am just curious as to whether the on board fuel management system will absorb the difference of air coming in and going out and adjust for it. Are larger injectors recommended, say 50lb. for this setup, or not.
Yes, making those changes without a tune/re-tune can definitely cause the engine to run too lean. Or even too rich depending on how the computer compensates or even overcompensates for the condition. It might not be to the point of 'danger' or damage if you're just driving it around easy (ie: not wide open throttle racing it every chance you get) but I wouldn't let it go too long like that. The MAF/PCM can correct/compensate for some of it to a point but it can't do it all...but proper tuning can.
And no, you shouldn't need new injectors for just bolt on mods like that.
Reply
Old Jan 24, 2012 | 06:08 PM
  #3  
Neumonic2002's Avatar
Neumonic2002
Drifting
15 Year Member
 
Joined: Oct 2004
Posts: 1,790
Likes: 29
From: STL MO
St. Jude Donor '09-'10
Default

^^Agreed^^

My tune was lean with just the addition of the 102 Fast, I already had long tubes and a tune when I installed it. Possibly worth noting, when I installed the 102 Fast intake i removed a ported LS2 intake.
Reply
Old Jan 24, 2012 | 10:25 PM
  #4  
C U IN REARVEIW's Avatar
C U IN REARVEIW
Le Mans Master
10 Year Member
 
Joined: Jan 2009
Posts: 5,656
Likes: 112
From: ocean springs mississippi
Default

Originally Posted by Neumonic2002
^^Agreed^^

My tune was lean with just the addition of the 102 Fast, I already had long tubes and a tune when I installed it. Possibly worth noting, when I installed the 102 Fast intake i removed a ported LS2 intake.
pm sent
Reply
Old Jan 24, 2012 | 11:12 PM
  #5  
NospdLimit's Avatar
NospdLimit
Racer
Supporting Lifetime Gold
 
Joined: Aug 2011
Posts: 487
Likes: 2
From: Henderson Co
St. Jude Donor '12-'13
Default

I would doubt you would see a lean condition adding those mods.
Some tuners think if it is not pig rich you need more fuel. That is not true.
Reply
Old Jan 25, 2012 | 10:46 AM
  #6  
haljensen's Avatar
haljensen
Race Director
Supporting Lifetime
 
Joined: Mar 2005
Posts: 10,399
Likes: 25
From: Austin Texas
Default

Since the computers control fuel and air it would be almost impossible to run lean enough to notice.

With more air the computer adds more fuel but the computer also controls the amount of air flow. Doesn't matter whether 90mm or 102mm TB, the computer controls how far the throttle opens and how much fuel flows.
Reply
Old Jan 26, 2012 | 07:50 AM
  #7  
marc8090's Avatar
marc8090
Burning Brakes
10 Year Member
 
Joined: Nov 2008
Posts: 940
Likes: 1
From: Long Island NY
Default

Originally Posted by haljensen
Since the computers control fuel and air it would be almost impossible to run lean enough to notice.

With more air the computer adds more fuel but the computer also controls the amount of air flow. Doesn't matter whether 90mm or 102mm TB, the computer controls how far the throttle opens and how much fuel flows.
Respectfully, not exactly. Sure the car is drive by wire but your right foot basically controls how much air enters the engine. You also have to consider open loop vs closed loop. Under part throttle in closed loop the O2 sensors will monitor the air fuel ratio and keep the mixture correct as long as the air coming in is within the parameters of the stock tuning. If you get to a point where more air is coming in than the tables are capable of handling, the car will run lean. At full throttle the car goes open loop where the O2 sensors are not used to monitor the air fuel ratio. It simply runs however it was calibrated by the engineers. If you add more airflow, and leave the stock tune alone, the mixture will be leaner at full throttle. If it goes too lean depends on how rich it was to begin with and how much air you have added.
Reply
Old Jan 26, 2012 | 11:06 AM
  #8  
Mike's LS3's Avatar
Mike's LS3
Safety Car
15 Year Member
Liked
Community Favorite
Top Answer: 1
 
Joined: Nov 2007
Posts: 4,433
Likes: 873
From: Bay Area CA
Default

Originally Posted by marc8090
Respectfully, not exactly. Sure the car is drive by wire but your right foot basically controls how much air enters the engine. You also have to consider open loop vs closed loop. Under part throttle in closed loop the O2 sensors will monitor the air fuel ratio and keep the mixture correct as long as the air coming in is within the parameters of the stock tuning. If you get to a point where more air is coming in than the tables are capable of handling, the car will run lean. At full throttle the car goes open loop where the O2 sensors are not used to monitor the air fuel ratio. It simply runs however it was calibrated by the engineers. If you add more airflow, and leave the stock tune alone, the mixture will be leaner at full throttle. If it goes too lean depends on how rich it was to begin with and how much air you have added.
Great explanation! In closed loop, once the engine runs too lean or too rich + or - 25% the ECM will throw codes. In open loop, there are no A/F ratio warnings!
Reply

Get notified of new replies

To Can engine run lean?

Corvette Stories

The Best of Corvette for Corvette Enthusiasts

story-0

150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

 Joe Kucinski
story-1

8 Coolest Corvette Pace Cars (and Replicas) of All Time

 Verdad Gallardo
story-2

Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)

 Joe Kucinski
story-3

Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!

 Verdad Gallardo
story-4

Top 10 Corvettes Coming to Mecum Indy 2026!

 Brett Foote
story-5

Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

 Michael S. Palmer
story-6

10 Revolutionary 'Corvette Firsts' Most People Don't Know

 Joe Kucinski
story-7

5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

 Michael S. Palmer
story-8

2027 Corvette vs The World: Every C8 vs Its Closest Competitor

 Joe Kucinski
story-9

10 Most Common Corvette Problems of the Last 20 Years!

 Joe Kucinski




All times are GMT -4. The time now is 11:43 PM.

story-0
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

Slideshow: From C1 to C8 we compare every Corvette generation by the numbers.

By Joe Kucinski | 2026-05-12 16:54:12


VIEW MORE
story-1
8 Coolest Corvette Pace Cars (and Replicas) of All Time

Slideshow: Some Corvette pace cars became collectible legends, while others perfectly captured the look and attitude of their era.

By Verdad Gallardo | 2026-05-11 09:50:51


VIEW MORE
story-2
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)

Slideshow: Ranking the top 10 Corvette engines by torque output.

By Joe Kucinski | 2026-05-05 11:58:09


VIEW MORE
story-3
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!

Slideshow: A Corvette pace car nearly matching IndyCar speeds sounds exaggerated, until you look at the numbers.

By Verdad Gallardo | 2026-05-04 20:03:36


VIEW MORE
story-4
Top 10 Corvettes Coming to Mecum Indy 2026!

Among a rather large group of them.

By Brett Foote | 2026-05-04 13:56:44


VIEW MORE
story-5
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

Slideshow: the top 10 things Corvette owners want in the C9 Corvette

By Michael S. Palmer | 2026-04-30 12:41:15


VIEW MORE
story-6
10 Revolutionary 'Corvette Firsts' Most People Don't Know

Slideshow: 10 Important Corvette 'firsts' that every fan should know.

By Joe Kucinski | 2026-04-29 17:02:16


VIEW MORE
story-7
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

Slideshow: Should you buy a 2020-2026 Corvette or wait for 2027?

By Michael S. Palmer | 2026-04-22 10:08:58


VIEW MORE
story-8
2027 Corvette vs The World: Every C8 vs Its Closest Competitor

Slideshow: 2027 Corvette lineup vs the world.

By Joe Kucinski | 2026-04-24 16:12:42


VIEW MORE
story-9
10 Most Common Corvette Problems of the Last 20 Years!

Slideshow: 10 major Corvette problems from the last 20 years.

By Joe Kucinski | 2026-04-14 16:37:05


VIEW MORE