Running Lean - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
Register Home Forums Photo Gallery Garage Search Today's Posts Mark Forums Read Auto Escrow
Engine Mods Talk about Chevy Cobalt Engine Modifications here.

YourCobalt.com is the premier Chevrolet Cobalt Forum on the internet. Registered Users do not see the above ads.
Closed Thread
 
LinkBack Thread Tools Display Modes
  #1  
Old 04-03-2011, 05:57 PM
black09cobalt's Avatar
Newcomer
 
Join Date: Dec 2009
Location: Bristolville, Ohio
Posts: 21
Garage
Send a message via AIM to black09cobalt
Running Lean

I recently finished my sc install and it drives fine with a good afr until i let off the gas, than my car goes full lean and stays that way for about a min. Or if i sit at an idle the car is fine but will go lean at random than it will level out. I have no check engine light but i can feel my car is not running like it should and dont want to drive it running lean. I checked injectors, vaccum, and plugs. when i changed my plugs back to factory instead of a step colder the problem seemed to get a little better. Im thinking maybe get another set of plugs in the morning but without a CEL im not sure how to go about fixing this.
__________________

09 cobalt ls, 94 firebird formula, 87 s10 sold
Sponsored Links
Advertisement
 
  #2  
Old 04-03-2011, 06:00 PM
dandaman15's Avatar
Forum Regular
 
Join Date: Jun 2010
Location: West Allis, WI
Posts: 197
Quote:
Originally Posted by black09cobalt View Post
I recently finished my sc install and it drives fine with a good afr until i let off the gas, than my car goes full lean and stays that way for about a min. Or if i sit at an idle the car is fine but will go lean at random than it will level out. I have no check engine light but i can feel my car is not running like it should and dont want to drive it running lean. I checked injectors, vaccum, and plugs. when i changed my plugs back to factory instead of a step colder the problem seemed to get a little better. Im thinking maybe get another set of plugs in the morning but without a CEL im not sure how to go about fixing this.

Are you letting completely off the gas when it does that, or just backing off while still having the pedal pressed a bit?
__________________

My Showoff Thread
  #3  
Old 04-03-2011, 06:05 PM
black09cobalt's Avatar
Newcomer
 
Join Date: Dec 2009
Location: Bristolville, Ohio
Posts: 21
Garage
Send a message via AIM to black09cobalt
completly off and even if i press a bit it still stays lean so imagine im pretty far off the gauge. when i give it gas though it imediatly goes back to normal.
__________________

09 cobalt ls, 94 firebird formula, 87 s10 sold
  #4  
Old 04-04-2011, 02:14 PM
dandaman15's Avatar
Forum Regular
 
Join Date: Jun 2010
Location: West Allis, WI
Posts: 197
That sounds fine to me. When you let completely off the gas the car should go into DFCO aka Deceleration Fuel Cut Off. Ofcourse its going to get lean since it turns the injectors off. Thats whats causing the crazy reading. As long as it returns to what it is tuned at when you get back on the gas it will be fine.
__________________

My Showoff Thread
  #5  
Old 04-04-2011, 04:20 PM
GpB311's Avatar
Veteran
 
Join Date: Jun 2010
Location: Los Angeles, CA
Posts: 675
Garage
Might be a dumb question, but you have your tune installed correctly and all that?
__________________
GpB311 Showoff Profile http://www.yourcobalt.com/forums/veh...ngeles-ca.html


You might also know me as Dick Thrusthumper...
  #6  
Old 04-04-2011, 08:26 PM
black09cobalt's Avatar
Newcomer
 
Join Date: Dec 2009
Location: Bristolville, Ohio
Posts: 21
Garage
Send a message via AIM to black09cobalt
I got my tune from trifecta and installed it without issue. I understand that it should run lean some but full lean (my aem afr wideband cant even register it) i was unsure of. Also sometimes at an idle it will decide to full lean and almost shut off (car shaking) but will even out on its own. I was thinking possibly i have a vaccum line hooked up incorrectly? I know I have the one to the throttle body correct but the little one on the intake and the bypass valve? Other than this I can't think of anything else. I have herd nothing but good about trifecta tunes so i highly doubt its a tune issue.
__________________

09 cobalt ls, 94 firebird formula, 87 s10 sold
  #7  
Old 04-04-2011, 09:40 PM
SHINKS07SS's Avatar
Sneezing Daily
Staff Alumni
YourCobalt.com Premium Member


 
Join Date: Apr 2008
Location: Wisconsin
Posts: 1,155
Garage
Your Idle needs to be sorted out, your short term fuel trims are probably off which is causing the car to almost misfire when you are idling and lean out every now and then. What is your aft at WOT? and the does your gauge do dashes --- Like that when it is going lean? that is normally the signal it will give you when your car goes into dfco.
__________________
M62 Powered for Now


S252 Next (Car is gonna be fast and Sneezing, lots!)
  #8  
Old 04-04-2011, 09:57 PM
black09cobalt's Avatar
Newcomer
 
Join Date: Dec 2009
Location: Bristolville, Ohio
Posts: 21
Garage
Send a message via AIM to black09cobalt
at WOT I am around 13.7 to 15.2 which i would imagine is ok. Yes I am getting the --- and aparently this is normal which is good (this was my main concern). So my only issue now is the short term fuel trim causing idle inconsistancies. Any ideas on what would cause this? And thank you all for the insight so far!
__________________

09 cobalt ls, 94 firebird formula, 87 s10 sold
  #9  
Old 04-05-2011, 10:33 AM
black09cobalt's Avatar
Newcomer
 
Join Date: Dec 2009
Location: Bristolville, Ohio
Posts: 21
Garage
Send a message via AIM to black09cobalt
Update: just got a CEL code Running to lean
__________________

09 cobalt ls, 94 firebird formula, 87 s10 sold
  #10  
Old 04-05-2011, 04:34 PM
SHINKS07SS's Avatar
Sneezing Daily
Staff Alumni
YourCobalt.com Premium Member


 
Join Date: Apr 2008
Location: Wisconsin
Posts: 1,155
Garage
You are running way to lean at WOT, when your pedal is all the way to the floor the leanest you should be running it 12.8, that is the max, most people only push it to 12.5... you can be causing some pretty bad damage to your motor, however, the numbers you posted up sound like your cruising afr?
__________________
M62 Powered for Now


S252 Next (Car is gonna be fast and Sneezing, lots!)
Sponsored Links
Advertisement
 
Closed Thread


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 07:32 AM.


Powered by vBulletin® Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.

Content Relevant URLs by vBSEO 3.3.2