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AFR at idle??

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Old 03-22-2007, 08:16 AM
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Question AFR at idle??

I've finally got my LC-1 installed and logging in hpt. I've got it wired directly into the PCM through EGR. Can someone help me understand if what I'm seeing is normal, or needs to be adjusted.

While at idle I'm seeing AFR between 14-22 I give it a little gas and is seems to be in the range of around 14-16. I don't have any other readings as of yet because I didn't have it working at the track this past weekend. I notice my AFR in hpt only goes up to 18, I'm assuming that's because I programed the LC-1 from 0v 10:1 & 5v 18:1. Should I modify this to maybe 22:1 at 5v and then modify my formula in hpt? Thanks.

-Bryan
Attached Files
File Type: hpl
idle_lc-1.hpl (62.0 KB, 55 views)
File Type: zip
test log 1.zip (2.8 KB, 14 views)

Last edited by NVE THIS; 03-22-2007 at 08:51 AM.
Old 03-22-2007, 08:20 AM
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Are you cammed? I wouldnt worry about AFR at idle as long as its not running rich. Lean idle is good.
Old 03-22-2007, 08:42 AM
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My idle will swing between high 14's and mid-15's at idle. It's a little rich, but it's where I want it.
Old 03-22-2007, 09:00 AM
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Originally Posted by brad8266
Are you cammed? I wouldnt worry about AFR at idle as long as its not running rich. Lean idle is good.
Yes, I have a FMS F14 cam. I spoke with Alan from FMS a while ago when I installed the cam and chagned a few settings to get the car to run. It actually runs pretty good, but I know it needs to be tuned. I put down 404HP/391TQ on the dyno this past Jan. and now am running it at the track. I went this past weekend and actually tore my driveshaft in half so looks like I need a new one now.

I can't do much tuning until I get a new DS, but want to get things toghether so I can have hpt ready to get my car the way it should be. I also have a 150 N2O shot I'll be running, but I'm going to get a good N/A tune. Thanks for any help.

-Bryan
Old 03-22-2007, 09:10 AM
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I thought Idle should be averaging @ 14.7 (or atmospheric pressure) of course it will vary but i thought that is the target AFR..
Old 03-22-2007, 09:36 AM
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Originally Posted by Flipn
I thought Idle should be averaging @ 14.7 (or atmospheric pressure) of course it will vary but i thought that is the target AFR..
If the car had a stock cam that didn't introduce fresh air into the exhaust via overlap, then yes, 14.7 is what you want to target. But, he's cam'd so it's a little different.
Old 03-22-2007, 09:48 AM
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Originally Posted by SSpdDmon
If the car had a stock cam that didn't introduce fresh air into the exhaust via overlap, then yes, 14.7 is what you want to target. But, he's cam'd so it's a little different.
What does that mean for tuning for me? Thanks.
Old 03-22-2007, 09:52 AM
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It means that if you want the car to operate in closed loop, it's going to idle rich. If you don't want it to idle rich, you need to trick it into open loop for idle.
Old 03-22-2007, 10:09 AM
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My car cold idle's around 20 to 1. I can't remember what the hot idle is because it's still winter.
Old 03-22-2007, 10:10 AM
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Originally Posted by SSpdDmon
It means that if you want the car to operate in closed loop, it's going to idle rich. If you don't want it to idle rich, you need to trick it into open loop for idle.
+1
Old 03-22-2007, 10:21 AM
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Originally Posted by SSpdDmon
It means that if you want the car to operate in closed loop, it's going to idle rich. If you don't want it to idle rich, you need to trick it into open loop for idle.
It really doesn't bother me if the car idles rich. It smells awesome actually But looking at my idle AFR, it looks like it's lean, right?
Old 03-22-2007, 10:45 AM
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Originally Posted by Flipn
I thought Idle should be averaging @ 14.7 (or atmospheric pressure) of course it will vary but i thought that is the target AFR..
You know the 14.7 psi of atmospheric pressure (standard day sea level) has nothing to do with the 14.7 parts air/fuel for combustion...right?
Old 03-22-2007, 11:54 AM
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Originally Posted by 98SS2836
My car cold idle's around 20 to 1. I can't remember what the hot idle is because it's still winter.
Are you sure that's not the WBO2 just warming up? It sounds a little hard to believe it will idle ok while being that lean.
Old 03-22-2007, 01:43 PM
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Originally Posted by SSpdDmon
Are you sure that's not the WBO2 just warming up? It sounds a little hard to believe it will idle ok while being that lean.
I can idle at over 17:1, no problem, lean idle is good.
Old 03-22-2007, 06:55 PM
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do you have the sensor on one side of the exhaust?
i had to move my wide band to the cat back
because of the fluctuations i was getting.
Old 03-22-2007, 09:42 PM
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Originally Posted by shoemike
do you have the sensor on one side of the exhaust?
i had to move my wide band to the cat back
because of the fluctuations i was getting.
I don't have CATS. I have the FLP Long Tubes and the pipes. I've got my WB O2 mouned in the pass. race pipe. The pipes also have cutouts in them.
Old 03-22-2007, 10:20 PM
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I'll give some updates to this tomorrow after I do a few things to it in the morning.
Old 04-02-2007, 04:41 PM
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sorry to bring up the old. but how do you "trick" it to open loop at idle? i've been having some problems idleing rich.
Old 04-02-2007, 05:53 PM
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Originally Posted by kamikazematt
sorry to bring up the old. but how do you "trick" it to open loop at idle? i've been having some problems idleing rich.
https://ls1tech.com/forums/pcm-diagnostics-tuning/670285-what-afr-should-you-seeing.html

SSpdDmon describes a way to do it in that thread.

R/

Frat
Old 04-02-2007, 10:59 PM
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mind giving some of those F14 tunning tips from alan out...I going to be trying my hand at this in the next few weeks after i install the new heads/intake




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