PCM Diagnostics & Tuning HP Tuners | Holley | Diablo
Sponsored by:
Sponsored by:

Why do I still have a lean idle in closed loop?

Thread Tools
 
Search this Thread
 
Old 12-10-2010, 10:08 PM
  #1  
On The Tree
Thread Starter
iTrader: (16)
 
osuhog's Avatar
 
Join Date: May 2010
Location: Stillwater, OK
Posts: 174
Likes: 0
Received 0 Likes on 0 Posts
Default Why do I still have a lean idle in closed loop?

All of this has been done within the last 24 hours via HP Tuners...

VE tuned with all cells no more than +-2.
MAF calibrated with all cells no more than +-2.
RAF tuned with the Russ K cfg file in D & in P.

All fuel trims were reset before tuning & they were all 0 before my initial post-tune start-up.

So, shouldn’t my AFR be pretty much spot on when I go to closed loop? I logged my closed loop idle a few minutes ago & I’m idling at 15 or greater afr.

Any ideas, or do I need to run the car for a while for the trims to settle in? I didn't think I would need to with VE, MAF, & RAF tuned.

I did notcie that the bank 2 ltft is bouncing around & logging negative #'s but none of the other fuel trims are. Do I possibly have a bad 02 sensor?

Thanks.

Attached Files
File Type: hpt
1999 WS6 Vert - 2010-12-10.hpt (451.3 KB, 191 views)
File Type: hpl
Idle Log.hpl (50.4 KB, 153 views)
Old 12-11-2010, 09:52 AM
  #2  
Moderator
iTrader: (11)
 
jimmyblue's Avatar
 
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,605
Likes: 0
Received 6 Likes on 6 Posts

Default

Long tubes at idle are making it hard to keep an O2 sensor
lit.

Try a little experiment. Reset the trims. Then high-idle it
with the pedal, like 3000 RPM or so, for a minute. Then
let it drop to idle while you watch the O2 switching
waveforms. If it starts off with a reasonable switching
density and symmetry, and over a minute or two becomes
irregular and starts to spend most of its time on the floor,
and trims start to creep, this (insufficient exhaust heat)
is your pony.
Old 12-13-2010, 06:35 AM
  #3  
Banned
iTrader: (1)
 
CalEditor's Avatar
 
Join Date: Feb 2008
Location: Rock Hill SC
Posts: 514
Likes: 0
Received 1 Like on 1 Post
Default

Are you running pump gas with E10%?
It looks like it
Old 12-13-2010, 07:22 AM
  #4  
Banned
iTrader: (10)
 
edcmat-l1's Avatar
 
Join Date: Jul 2006
Location: Va Beach
Posts: 4,782
Likes: 0
Received 4 Likes on 4 Posts
Default

Based on your WB, you HPT thinks it's a 5.5% error in fueling, but your NB and PCM only think it's a 1.6% error on one side. I wouldn't sweat it. Too many things come into play with a cammed car @ idle. Overlap, long tubes, O2 and WB location. Different WBs have different levels of accuracy, and at the end of the day, it doesn't really matter what they read or think at part throttle, the fuel trims are gonna do their thing. Keep them happy, worry about your A/F at WOT.
Old 12-13-2010, 11:12 AM
  #5  
LS1 Tech Administrator
iTrader: (14)
 
Patrick G's Avatar
 
Join Date: Nov 2001
Location: Victoria, TX
Posts: 8,244
Likes: 0
Received 31 Likes on 27 Posts

Default

I would make sure that your O2 switch points are all at 450mv. That can also be a problem with doing STFT tuning. Sometimes light loads have you at 350mv which will make you slightly leaner at idle and light loads.
__________________

2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
Old 12-14-2010, 10:22 AM
  #6  
On The Tree
Thread Starter
iTrader: (16)
 
osuhog's Avatar
 
Join Date: May 2010
Location: Stillwater, OK
Posts: 174
Likes: 0
Received 0 Likes on 0 Posts
Default

Thanks for the comments guys.

No e10, only 100% gasoline.

I did find out that my WB gauge is reading about .2 too high, so it's going in for warranty service.

I suspect the long tubes or possibly a small leak at the band clamp on the header collector might be giving me some problems at idle keeping it from being perfect also. But like was mentioned above, the fuel trims take care of that, so it's all good.

WOT AFR is great & even accross the board, although with my WB reading .2 lean, it's actually .2 richer than I'm commanding as set up with my WB. I'm okay with that until I get the WB gauge recalibrated though. If I tuned it too lean, that would be a different story, obviously.

Thanks again for the help.
Old 12-14-2010, 04:26 PM
  #7  
FormerVendor
iTrader: (45)
 
Frost's Avatar
 
Join Date: Jul 2005
Location: Richmond VA
Posts: 5,913
Likes: 0
Received 2 Likes on 2 Posts
Default

e10 is sold at pumps as regular gasoline...
Old 12-14-2010, 04:40 PM
  #8  
Banned
iTrader: (1)
 
CalEditor's Avatar
 
Join Date: Feb 2008
Location: Rock Hill SC
Posts: 514
Likes: 0
Received 1 Like on 1 Post
Default

The Target AFR is set to 14.63 and the PCM is trying to get to that using the Fuel Trims.

The way I look at it if the Wide-Band is properly installed and known to be giving the correct reading then the tune is off. That is why I use a Wide-Band. To check the PCM.

Know I did up a paper some place and if I recall 14.68 = 15.23 if you have E10% on a Wide-Band.
If you change the Target AFR to 14.1 and you have E10% the Wide-Band read Lambda of 1.0. The ignorant Guage will say that the AFR is 14.7, because it is programmed that way.
Old 12-14-2010, 08:08 PM
  #9  
TECH Senior Member
iTrader: (25)
 
2xLS1's Avatar
 
Join Date: Nov 2001
Location: Warr Acres, OK
Posts: 5,649
Likes: 0
Received 8 Likes on 8 Posts

Default

Originally Posted by Frost
e10 is sold at pumps as regular gasoline...
Not in Oklahoma. Well not labled as such. Any alcohol tainted gasoling requires a label on the pump. State law. We still have lots of 100% gas and stations advertise it with big banners.
Old 12-14-2010, 08:16 PM
  #10  
Banned
iTrader: (1)
 
CalEditor's Avatar
 
Join Date: Feb 2008
Location: Rock Hill SC
Posts: 514
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by 2xLS1
Not in Oklahoma. Well not labled as such. Any alcohol tainted gasoling requires a label on the pump. State law. We still have lots of 100% gas and stations advertise it with big banners.
Federal Law is E10%
Old 12-14-2010, 09:24 PM
  #11  
TECH Senior Member
iTrader: (25)
 
2xLS1's Avatar
 
Join Date: Nov 2001
Location: Warr Acres, OK
Posts: 5,649
Likes: 0
Received 8 Likes on 8 Posts

Default

Originally Posted by CalEditor
Federal Law is E10%
Oh, so you know more about the gasoline sold in Oklahoma than someone that lives here.
Old 12-14-2010, 09:46 PM
  #12  
On The Tree
Thread Starter
iTrader: (16)
 
osuhog's Avatar
 
Join Date: May 2010
Location: Stillwater, OK
Posts: 174
Likes: 0
Received 0 Likes on 0 Posts
Default

Wow, it's not like this everywhere? 2xLS1 is indeed correct. OK state law requires e10 pumps to be labeled as such. Most every gas station around here that doesn't sell e10 advertises "NO ETHANOL" on their marquee. I don't even pull in to a station unless they have a sign that says "NO ETHANOL".

As far as my issue, I'm working on making sure the v-band clamp is absolutely sealed at the header collector. Between that & getting my wideband gauge fixed to read correctly, I think I'll be spot on.
Old 12-16-2010, 06:22 PM
  #13  
On The Tree
Thread Starter
iTrader: (16)
 
osuhog's Avatar
 
Join Date: May 2010
Location: Stillwater, OK
Posts: 174
Likes: 0
Received 0 Likes on 0 Posts
Default

A possible leak around the WB 02 bung was suggested to me over on the HPT forum. I never found an actual leak, but I used some hi-temp rtv aroud the bung & I also removed the vband clamp from the header collector & smeared some rtv on & re-installed.

Much better now! My WB gauge is much more stable now & it doesnt bounce around nearly as much. I obviously had a very small leak somewhere around that bung.

I think the only issue I have now is because of the long tubes as jimmyblue suggested (thanks!). It's still reading 3-4% lean after idling for a while. If I give it some throttle for a block or 2, it seems like it's warming up the 02's & then it reading perfectly at idle again. That is until it idles for another minute or 2, then it goes back to reading lean again.

Tell me this. Obviously my 02's will be adding fuel in closed loop as it reads a little lean at idle (when it's cold outside anyway). I know my VE & MAF are tuned spot on at idle after making sure the sensor was completely warm as I tuned. Is there any way I can run open loop at idle & then CL everywhere else with HP Tuners? I'm afraid my ltft's are going to add fuel at idle keeping me rich all the time down there, at least in the winter when it's cold outside.

Any other ideas or suggestions?

Thanks again!

Last edited by osuhog; 12-16-2010 at 08:56 PM.
Old 12-16-2010, 08:24 PM
  #14  
TECH Fanatic
iTrader: (6)
 
patSS/00's Avatar
 
Join Date: Nov 2001
Location: AZ
Posts: 1,005
Received 14 Likes on 12 Posts

Default

Originally Posted by osuhog
Any way I can run open loop at idle & then CL everywhere else?

Thanks again!
Efilive has a custom os with something called semi open loop, which lets you set open or closed loop depending on map and rpm (I think - I haven't used it just read the tutorial).



Quick Reply: Why do I still have a lean idle in closed loop?



All times are GMT -5. The time now is 09:50 AM.