2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.
Sponsored by:

rich or lean at idle?

Thread Tools
 
Search this Thread
 
Old 10-21-04, 01:02 AM
  #1  
Senior Member

Thread Starter
 
Chance's Avatar
 
Join Date: Jul 2001
Location: Chatsworth, CA
Posts: 273
Likes: 0
Received 0 Likes on 0 Posts
rich or lean at idle?

I have a S5 TII and was wondering if it should run rich or lean at idle? It seems to vary from time to time but the idle is noticeably smoother when it's rich. What would cause the a/f ratio at idle to vary? Thanks.
Old 10-21-04, 01:14 AM
  #2  
Microtech Tuning!

 
Infini IV's Avatar
 
Join Date: Feb 2002
Location: 626 Socal
Posts: 1,828
Likes: 0
Received 0 Likes on 0 Posts
What specific AFR's determines rich or lean when you say that? I know when my friend (guitarjunkie on the boards) and I were tuning with his wideband, my car wouldn't want to idle at anything leaner than 13.5:1 AFR.
Old 10-21-04, 01:17 AM
  #3  
Banned. I got OWNED!!!
 
DerangedHermit's Avatar
 
Join Date: Jan 2004
Location: Knoxville, TN 37916
Posts: 2,040
Likes: 0
Received 5 Likes on 2 Posts
I would say to run it as lean as possible within a safe margin. No reason to waste all that extra gas. Then again, that's my theory.
Old 10-21-04, 01:26 AM
  #4  
HAILERS

 
HAILERS's Avatar
 
Join Date: May 2001
Location: FORT WORTH, TEXAS,USA
Posts: 20,563
Likes: 0
Received 21 Likes on 19 Posts
Personal experiece says they run smoother at around 13 to 1 afr. When run leaner they go poo poo, puff puff, all the time at idle. I've no idea why yours changes at idle...from lean to rich or whatever it is doing, all by itself. Could be several things that I'm sure someone else will pipe in with.
Old 10-21-04, 02:19 AM
  #5  
Senior Member

Thread Starter
 
Chance's Avatar
 
Join Date: Jul 2001
Location: Chatsworth, CA
Posts: 273
Likes: 0
Received 0 Likes on 0 Posts
I'm not sure what afr's I'm running at idle. I'm just going by a narrowband a/f guage and SAFC. I have the O2 sensor hooked up to the SAFC so I can get a voltage reading from the sensor check screen. When the voltage is at 0, it idles as Hailers described and the engine just feels more shakey. Other times it'll read at .8xx volts and idle really smooth. I just find it odd that it's not constant and would like to fix whatever the problem could be.
Old 10-21-04, 04:03 AM
  #6  
Alcohol Fueled!

iTrader: (2)
 
J-Rat's Avatar
 
Join Date: Jan 2002
Location: Hood River oregon
Posts: 11,093
Likes: 0
Received 2 Likes on 2 Posts
For some ungodly reason, my car seems to like 12.5 idle mixtures.

ITs a fuel hogging bitch....
Old 10-21-04, 04:36 PM
  #7  
Senior Member

Thread Starter
 
Chance's Avatar
 
Join Date: Jul 2001
Location: Chatsworth, CA
Posts: 273
Likes: 0
Received 0 Likes on 0 Posts
ttt
Old 10-21-04, 06:27 PM
  #8  
Lives on the Forum

 
WAYNE88N/A's Avatar
 
Join Date: Feb 2004
Location: Coldspring TX
Posts: 5,721
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by Chance
I'm not sure what afr's I'm running at idle. I'm just going by a narrowband a/f guage and SAFC. I have the O2 sensor hooked up to the SAFC so I can get a voltage reading from the sensor check screen. When the voltage is at 0, it idles as Hailers described and the engine just feels more shakey. Other times it'll read at .8xx volts and idle really smooth. I just find it odd that it's not constant and would like to fix whatever the problem could be.
.8v is about what you'll see on a stock setup. Even with all of my recent "lean during cruise problems", she always went back to .8 at idle, so you've got yourself one funky problem there. Check the variable resistor input at the ECU, maybe you have an intermittent snafu at the resistor out on the right strut tower causing her to go lean at idle. Either that, or you have a nice vac leak that may be intermittent...
Old 10-22-04, 12:48 AM
  #9  
HAILERS

 
HAILERS's Avatar
 
Join Date: May 2001
Location: FORT WORTH, TEXAS,USA
Posts: 20,563
Likes: 0
Received 21 Likes on 19 Posts
If you see .8v at idle.....you've got problems if you still have your airpump and acv and solenoids working. A stock RX at idle should see zippity doo dah at idle. Maybe .1 or .2, certainly not .8. That .8v indicates a lack of air getting to the exaust ports at idle ...from the airpump.
Old 10-22-04, 01:10 AM
  #10  
Senior Member

Thread Starter
 
Chance's Avatar
 
Join Date: Jul 2001
Location: Chatsworth, CA
Posts: 273
Likes: 0
Received 0 Likes on 0 Posts
No airpump or acv on the car anymore. Should the car constantly be idleing around .8 without them? Looks like I'll be checking for vacuum leaks and going from there. Thanks for all the input so far.
Old 10-22-04, 02:45 AM
  #11  
Lives on the Forum

 
WAYNE88N/A's Avatar
 
Join Date: Feb 2004
Location: Coldspring TX
Posts: 5,721
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by HAILERS
If you see .8v at idle.....you've got problems if you still have your airpump and acv and solenoids working. A stock RX at idle should see zippity doo dah at idle. Maybe .1 or .2, certainly not .8. That .8v indicates a lack of air getting to the exaust ports at idle ...from the airpump.
Oops, my bad...It's been so long since I've had port air, I probably never took O2 sensor readings for comparison when that system was operational. That .8v I'm refering to is normal WITHOUT the port air system functioning (i.e. no ACV). Good for you, Hailers, you busted me
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
barkz
Power FC Forum
37
11-21-20 09:34 AM
R.O.D
2nd Generation Specific (1986-1992)
34
01-06-16 12:09 AM
R.O.D
Rtek Forum
1
09-23-15 01:15 AM
ZacMan
Build Threads
4
09-19-15 09:20 PM
Monsterbox
Adaptronic Engine Mgmt - AUS
5
09-11-15 03:29 PM



Quick Reply: rich or lean at idle?



All times are GMT -5. The time now is 02:05 AM.