Tuning closed loop idle
08-11-2004, 12:46 PM
#46
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Join Date: Jul 2002
Location: North, SC, USA
Posts: 659
Re: Tuning closed loop idle
If you have tunercat, send it to me too.
I was going to put my input on my desktop dyno, and it will tell me the VE for my combo, and I want to see how it corresponds with your's, of course it's gonna have differences due to cam and head flows, but a general idea.
Fellas, I didn't want to stir up a hornets nest when I began this post, but I'm glad to see the answer. I'm not glad for what the answer is, I'm just glad that I'm not going to try and chase down the goast that everyone else has found out that does not exist. Kinda like looking for that pot of gold at the end of the rainbow, or that cure for my fat old ladies stinking feet, which doesn't exist.
Though once we was told that water and vinegar will clean lots of things.
D Moss
I was going to put my input on my desktop dyno, and it will tell me the VE for my combo, and I want to see how it corresponds with your's, of course it's gonna have differences due to cam and head flows, but a general idea.
Fellas, I didn't want to stir up a hornets nest when I began this post, but I'm glad to see the answer. I'm not glad for what the answer is, I'm just glad that I'm not going to try and chase down the goast that everyone else has found out that does not exist. Kinda like looking for that pot of gold at the end of the rainbow, or that cure for my fat old ladies stinking feet, which doesn't exist.
Though once we was told that water and vinegar will clean lots of things.
D Moss
08-11-2004, 02:52 PM
#51
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Join Date: Dec 2002
Posts: 752
Re: Tuning closed loop idle
well my tables are not completely tuned yet, but i will show you what i got for now 
Remember I didnt get a chance to make alot of tuning correction before I found my header gasket leak, but this will get you big cammed guys in the general area.
THIS TUNE ONLY SHOWS VE TABLE CHANGES, cant give you all my entire tune...hehh
http://www.tripintaz.com/file/TazVE.LT1
Remember I didnt get a chance to make alot of tuning correction before I found my header gasket leak, but this will get you big cammed guys in the general area.
THIS TUNE ONLY SHOWS VE TABLE CHANGES, cant give you all my entire tune...hehh
http://www.tripintaz.com/file/TazVE.LT1
Last edited by TriPinTaZ; 08-11-2004 at 02:54 PM.
08-11-2004, 05:02 PM
#53
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Join Date: Dec 2002
Posts: 752
Re: Tuning closed loop idle
Originally Posted by dmoss69
Must be LT1 edit. 
<<<couldn't view it
<<<couldn't view it
http://www.tripintaz.com/file/TuneConv.exe
08-11-2004, 09:43 PM
#55
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Join Date: Dec 2002
Posts: 752
Re: Tuning closed loop idle
Maybe I should have mentioned that its an OBD2 .LT1 file. So tunercat cant view it and neither can OBD1 version on LT1 edit.
Ill have to make pictures of my tables and get them on here, i should get them up by tomorrow.
Ill have to make pictures of my tables and get them on here, i should get them up by tomorrow.
08-12-2004, 01:14 AM
#56
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Join Date: May 1999
Location: Charlottesville, VA, USA
Posts: 175
Re: Tuning closed loop idle
Hey Everyone,
I'm very tempted to stay quiet here, but I'll see if I can help a little bit.
David, you original post asked if there was a way to have a big cam idle in closed loop without adjusting the fueling way out of wack. The short answer you alluded to is correct, the closed loop feedback system isn't going to handle a big cam. This is due to the unburnt oxygen causing a false lean reporting from the O2 sensors, causing the downward spiral of the pcm dumping more fuel.
So since that answer isn't what anyone wants to hear, the real question is: "How can I get my car idling as smooth as possible with this large cam?" If the answer isn't closed loop, then it must be open loop (simple boolean logic there) Now that we've decided open loop, do we want open loop all the time or just some of time? Supposing the O2s report fine once the engine gets over 2000 rpm and you'd like the benefits of a closed loop system at that point, I'd say going open loop idle would be the way to go. The closest we have is Power Enrichement idle.
Side note: One thing that can help to smooth out lower rpm's is slightly advanced timing. I say slightly because too much timing can cause NOx emissions to spike. Really depends on the cam and the setup. Bigger displacement engines are more efficient at lower rpm's so a larger cam often behaves much nicer in those setups. I'd keep closed throttle spark below 28 degrees on a 350 LT1 for reference.
Back to open loop idle. Thought of this years ago and it's worked well for lots. Simply adjust you WOT vs TPS to 0 at the lower rpm range that you want to run open loop at. We'll get to PE vs. RPM adjustments in a sec. As Bunker mentioned the PCM will continue to try and learn, given enough time in WOT mode you will see the BLM's start to trim fuel. How can this be? Well, PE mode can exist in both open loop and closed loop (since they just state the preparedness of the O2's for feedback.) So, given this fact we need to lock the BLM's in PE mode. I wrote the BLM locker years ago, can be used on OBD1 .LT1 and .BIN files. here's the download location:
http://www.carprogrammer.com/WOT_BLM_Locker/
After applying the BLM locker, the BLM's won't move during PE Idle. Now the PE vs. RPM table can be used to fine tune AFR for idle. I can adjust WOT AFR by a tenth of a point using the PE vs RPM table, so nailing down idle will be possible. Bunker/ Matt was correct when he pointed out oxygen can't be used to meter combustion since it's not a byproduct. CO isn't a bad choice, but I'd recommend CO2 since maximum Carbon Dioxide indicates peak combustion efficiency, take a quick look here for a chart and brief explanation why:
http://www.carprogrammer.com/Z28/PCM...IONS%20h56.pdf
So if you've got access to an emissions place with an infrared 5 gas analyzer you're set, but if not like Matt said you can use a CO meter, which are much less expensive. Anyone remember the old gas analyzer that people used on motorcycles? They're under $100 and all over Ebay. I have a similar model pictured here:
http://www.carprogrammer.com/Z28/ExhaustAnalyzer/
Since it's measuring CO, and CO levels drop off past 14.7:1 (stoich) the best bet is to find where it's above 2%, then lean until it starts to drop down to .5 - 1%. That will be the best someone can do that doesn't have access to an emissions station. It doesn't really take that long, just a couple flashes should have you there.
Hope this helps,
-Christian
I'm very tempted to stay quiet here, but I'll see if I can help a little bit.
David, you original post asked if there was a way to have a big cam idle in closed loop without adjusting the fueling way out of wack. The short answer you alluded to is correct, the closed loop feedback system isn't going to handle a big cam. This is due to the unburnt oxygen causing a false lean reporting from the O2 sensors, causing the downward spiral of the pcm dumping more fuel.
So since that answer isn't what anyone wants to hear, the real question is: "How can I get my car idling as smooth as possible with this large cam?" If the answer isn't closed loop, then it must be open loop (simple boolean logic there) Now that we've decided open loop, do we want open loop all the time or just some of time? Supposing the O2s report fine once the engine gets over 2000 rpm and you'd like the benefits of a closed loop system at that point, I'd say going open loop idle would be the way to go. The closest we have is Power Enrichement idle.
Side note: One thing that can help to smooth out lower rpm's is slightly advanced timing. I say slightly because too much timing can cause NOx emissions to spike. Really depends on the cam and the setup. Bigger displacement engines are more efficient at lower rpm's so a larger cam often behaves much nicer in those setups. I'd keep closed throttle spark below 28 degrees on a 350 LT1 for reference.
Back to open loop idle. Thought of this years ago and it's worked well for lots. Simply adjust you WOT vs TPS to 0 at the lower rpm range that you want to run open loop at. We'll get to PE vs. RPM adjustments in a sec. As Bunker mentioned the PCM will continue to try and learn, given enough time in WOT mode you will see the BLM's start to trim fuel. How can this be? Well, PE mode can exist in both open loop and closed loop (since they just state the preparedness of the O2's for feedback.) So, given this fact we need to lock the BLM's in PE mode. I wrote the BLM locker years ago, can be used on OBD1 .LT1 and .BIN files. here's the download location:
http://www.carprogrammer.com/WOT_BLM_Locker/
After applying the BLM locker, the BLM's won't move during PE Idle. Now the PE vs. RPM table can be used to fine tune AFR for idle. I can adjust WOT AFR by a tenth of a point using the PE vs RPM table, so nailing down idle will be possible. Bunker/ Matt was correct when he pointed out oxygen can't be used to meter combustion since it's not a byproduct. CO isn't a bad choice, but I'd recommend CO2 since maximum Carbon Dioxide indicates peak combustion efficiency, take a quick look here for a chart and brief explanation why:
http://www.carprogrammer.com/Z28/PCM...IONS%20h56.pdf
So if you've got access to an emissions place with an infrared 5 gas analyzer you're set, but if not like Matt said you can use a CO meter, which are much less expensive. Anyone remember the old gas analyzer that people used on motorcycles? They're under $100 and all over Ebay. I have a similar model pictured here:
http://www.carprogrammer.com/Z28/ExhaustAnalyzer/
Since it's measuring CO, and CO levels drop off past 14.7:1 (stoich) the best bet is to find where it's above 2%, then lean until it starts to drop down to .5 - 1%. That will be the best someone can do that doesn't have access to an emissions station. It doesn't really take that long, just a couple flashes should have you there.
Hope this helps,
-Christian
08-12-2004, 01:23 AM
#57
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Join Date: May 1999
Location: Charlottesville, VA, USA
Posts: 175
Re: Tuning closed loop idle
To add a couple things:
For the ODB2 crowd Ken made the BLM locker available as part of recent OBD2 LT1 edit releases, so you'll be able to get it there. Dunno if he's addressed the LS1 Edit crowd with that yet.
On an OBD1 car I recommend a factory MAF setup and factory MAF tables. misreporting airflow just causes more adjustments in other places, it doesn't change the feedback of the O2's. The pcm will adjust, or the user will need to in other places. Stock MAF's have been good on lots of 400-500+ rwhp NA setups and many 700+ Forced Induction setups, it's been proven by many people they don't present a restriction, but everyone is entitled to their own beliefs, just my experience. VE tables aren't used in 94-95 MAF setups if the MAF is reporting correctly, so don't waste any time there.
Hope this helps,
-Christian
For the ODB2 crowd Ken made the BLM locker available as part of recent OBD2 LT1 edit releases, so you'll be able to get it there. Dunno if he's addressed the LS1 Edit crowd with that yet.
On an OBD1 car I recommend a factory MAF setup and factory MAF tables. misreporting airflow just causes more adjustments in other places, it doesn't change the feedback of the O2's. The pcm will adjust, or the user will need to in other places. Stock MAF's have been good on lots of 400-500+ rwhp NA setups and many 700+ Forced Induction setups, it's been proven by many people they don't present a restriction, but everyone is entitled to their own beliefs, just my experience. VE tables aren't used in 94-95 MAF setups if the MAF is reporting correctly, so don't waste any time there.
Hope this helps,
-Christian
08-12-2004, 06:41 AM
#58
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Join Date: Aug 2000
Location: North Vancouver, BC
Posts: 4,305
Re: Tuning closed loop idle
Exactly, the VE table is only referenced to by the PCM is the MAF fails in 94-95 OBDI cars. As for PE idle tunning I figured I'd try that a while back but ran into a problem, I think it was getting it to work properly you needed to alter the WOT TPS table so your in PE mode at 0% TPS, prblem is if I'm ideling at 1000rpm the next WOT cell was 1200, then the next was 1600, so if my WOT table was set to 0 from 400-1200 RPM, between 1200-1600 rpm would be a problem because the car would get in & out of PE mode unexpectedly, cuz at say 1400 rpm at 0 % you would be out of PE mode but at 30% you would be in PE mode because 1200 being at 0 & 1600 being at 60% between the two the PCM would just average out a number, its not a problem if you idle at 800 rpm, but if you idle at 1000 the best bet was to set the 1200rpm mark at like 40% or so, dunno its that which messed me up but I'm sure there is a sweet number in there if you can figure how you drive.
Matt.
Matt.
08-12-2004, 09:58 AM
#59
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Join Date: Jul 2002
Location: North, SC, USA
Posts: 659
Re: Tuning closed loop idle
I believe I'd like running like this better.
I want to keep the closed loop function since it works great cruising.
Being in PE doesn't bother me at idle, as long as I can dial it in and not throw gas out of the tail pipe.
I'll try the PE version, and see what happens.
I'm still going to change my VE tables, cause I've seen on this site where if you change the VE to closely match your engine's effeciency, then when your car does need to use the speed densitiy mode, it will be right.
I also have to change my MAF tables since mine has been ported.
KEEP THIS GOING!!! This is one great educational post for everyone.
Thanks
D Moss
I want to keep the closed loop function since it works great cruising.
Being in PE doesn't bother me at idle, as long as I can dial it in and not throw gas out of the tail pipe.
I'll try the PE version, and see what happens.
I'm still going to change my VE tables, cause I've seen on this site where if you change the VE to closely match your engine's effeciency, then when your car does need to use the speed densitiy mode, it will be right.
I also have to change my MAF tables since mine has been ported.
KEEP THIS GOING!!! This is one great educational post for everyone.
Thanks
D Moss
08-12-2004, 10:34 AM
#60
Registered User
Join Date: May 1999
Location: Charlottesville, VA, USA
Posts: 175
Re: Tuning closed loop idle
Life is too short to spend time tweaking VE tables that won't be referenced, but hey it's a free country
Ditched the ported MAF and get a nice stocker, it's one less thing to elliminate when you're trying to figure out why you AFR or BLMs are off.
Bunker/ Matt you've got a good understanding of the interpolation going on with values between table values, use it to your advantage. If you need to set 1600 to 0% TPS that's fine too. I can't see spending much time cruising below 2000 rpm in a big cam car anyway.
Give it a try, share your experiences.
-Christian
Ditched the ported MAF and get a nice stocker, it's one less thing to elliminate when you're trying to figure out why you AFR or BLMs are off.
Bunker/ Matt you've got a good understanding of the interpolation going on with values between table values, use it to your advantage. If you need to set 1600 to 0% TPS that's fine too. I can't see spending much time cruising below 2000 rpm in a big cam car anyway.
Give it a try, share your experiences.
-Christian