Notices
Series I Tech Garage The place to discuss anything technical about the RX-8 that doesn't fit into any of the categories below.

AFR at idle

Thread Tools
 
Rate Thread
 
Old Aug 11, 2006 | 01:18 PM
  #1  
tuj's Avatar
tuj
Thread Starter
Registered
 
Joined: Jan 2005
Posts: 615
Likes: 0
AFR at idle

What is the stock AFR value at idle (or what range of values does the car typically see)?
Reply
Old Aug 11, 2006 | 01:44 PM
  #2  
zoom44's Avatar
Administrator
 
Joined: Jul 2002
Posts: 21,958
Likes: 115
From: portland oregon
14.xx warm
Reply
Old Aug 11, 2006 | 01:57 PM
  #3  
tuj's Avatar
tuj
Thread Starter
Registered
 
Joined: Jan 2005
Posts: 615
Likes: 0
Yeah? I know we run pig rich up high in the rpms, but I thought there was talk that we were running rich sometimes at low rpms/low load/idle to cool the cat?
Reply
Old Aug 11, 2006 | 02:08 PM
  #4  
mysql101's Avatar
⎝⏠⏝⏠⎠
 
Joined: Apr 2004
Posts: 8,625
Likes: 5
From: USA
I'm seeing a bouncing idle afr from 14 up to 17 and back. I don't know what could be causing the bounce.
Reply
Old Aug 11, 2006 | 02:19 PM
  #5  
zoom44's Avatar
Administrator
 
Joined: Jul 2002
Posts: 21,958
Likes: 115
From: portland oregon
befroe the car is warmed up it is not hunting stoich since its in open loop. when its warm and closed loop it hunts stoich at idle
Reply
Old Aug 11, 2006 | 02:21 PM
  #6  
mysql101's Avatar
⎝⏠⏝⏠⎠
 
Joined: Apr 2004
Posts: 8,625
Likes: 5
From: USA
What I'm seeing is a bouncing AFR, warmed up and in closed loop. I can also see the AFR bouncing as I drive it down the highway - low rpm, closed loop.

I think there is a leak in the system since I am not holding boost as I should (Might be as simple as the BOV being too loose), but I don't know if that would cause the AFR to bounce even at idle...
Reply
Old Aug 11, 2006 | 02:54 PM
  #7  
tuj's Avatar
tuj
Thread Starter
Registered
 
Joined: Jan 2005
Posts: 615
Likes: 0
So (and yes I know this comes up all the time), what is to blame for the fuel milage (or lack thereof)? I understand that the rotary combustion chamber shape is thermally inefficient, but besides that, where are we loosing so much in everyday driving?

It looks to be like the lamda values up to 4k are pretty reasonable off the stock tune on the dyno's I've seen, although I'm sure those were done at WOT which probably throws things off a bit.

I consistently get 13 mpg in city driving (this is over two years of ownership, and 4 different flashes), shifting at 4k, crusing in 4th. I get 20-22 on the hwy crusing at 75.

BTW: I'm talking about the STOCK cars here.
Reply
Old Aug 11, 2006 | 03:00 PM
  #8  
zoom44's Avatar
Administrator
 
Joined: Jul 2002
Posts: 21,958
Likes: 115
From: portland oregon
shift at 3k cruise in 6th. dont take short trips. short trips mean time spent not warm. when its not warm the car is not in closed loop. lots of short trips mean lots of time spent NOT in closed loop. means it sucks fuel. that trip around the block for lunch will cost you 2 mpg at least a fill up. on the highway cruise at 70 to get 24
Reply
Old Aug 11, 2006 | 03:12 PM
  #9  
tuj's Avatar
tuj
Thread Starter
Registered
 
Joined: Jan 2005
Posts: 615
Likes: 0
Yeah, heard all those tips before. Cruise around town in 6th? No thanks. Short trips: can't help it that my commute has become short.

Just wanted to confirm that the normal idle AFR's weren't the issue. What kind of AFR's does it run at idle during startup enrichment?
Reply
Old Aug 11, 2006 | 03:29 PM
  #10  
zoom44's Avatar
Administrator
 
Joined: Jul 2002
Posts: 21,958
Likes: 115
From: portland oregon
at about 42 -43 with cars in front of you you should be in 6th above 35 you should be in 5th. downshift when you need extra oomph- thats why you have gears. as for the short commute- i heard someone say recently their commute since they moved was like 6 minutes if all the lights were green. my question- why are they driving? walk or ride a bike
Reply
Old Aug 11, 2006 | 03:40 PM
  #11  
tuj's Avatar
tuj
Thread Starter
Registered
 
Joined: Jan 2005
Posts: 615
Likes: 0
Originally Posted by zoom44
i heard someone say recently their commute since they moved was like 6 minutes if all the lights were green. my question- why are they driving? walk or ride a bike
We're way OT now, but believe it or not, it does rain, snow, and get hot and cold outside. Walking / biking are not always answers. Public transit? Ha, most of America has yet to really get that concept.
Reply
Old Aug 11, 2006 | 04:44 PM
  #12  
two rotors's Avatar
Registered User
 
Joined: Dec 2003
Posts: 431
Likes: 1
From: Whitby Ont
My A/F is consistently in the 14.3-14.8 range at idle when warm.It takes a few seconds for the O2 sensor to warm up on a cold start,but my A/F is in this range as soon as the O2 sensor warms up.My LTFT at idle is -18% these days.
The trick for fuel economy is the position of the the throttle pedal.Having the Greddy E-01 with the boost gauge is useful keeping manifold pressure as low as possible and hence consuming small quantities of fuel.
Unfortunately the turbo is really bad for prompting you to make positive pressure in the manifold and hence consuming copious quantities of fuel.
Reply
Old Aug 11, 2006 | 04:59 PM
  #13  
zoom44's Avatar
Administrator
 
Joined: Jul 2002
Posts: 21,958
Likes: 115
From: portland oregon
raingear, winter coats, l drive when its too bad
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
theblinkof
Series I Trouble Shooting
33
Oct 4, 2023 05:24 PM
Shankapotamus3
Series I Trouble Shooting
28
Mar 14, 2021 03:53 PM
Danield97
Series I Trouble Shooting
1
Sep 30, 2015 05:59 PM
Quiggs321
New Member Forum
19
Sep 30, 2015 05:34 PM



You have already rated this thread Rating: Thread Rating: 0 votes,  average.


All times are GMT -5. The time now is 04:56 PM.