2 Bar Stock PCM Speed Density Tune for >6psi (Forced Induction)
12-27-2007, 11:17 AM
#31
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Join Date: Mar 2002
Location: San Juan PR
Posts: 3,083
If the pcm could be changed it would be a lot easier for everything... You could extend the tables and a few other things... Some guy did it... but he never released the code.. He is Ken from hp tuners.
01-19-2008, 03:51 PM
#32
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Join Date: Aug 2007
Posts: 573
2 Bar LT1 Stock PCM Update
I have an update to how the Stock PCM reacts to 2 Bar tune...
While I still dont see any real negative side affects from using the 2 bar setup on the LT1 PCM (still looking but I dont see any problems yet) I would like to better understand how the Baro affects the tune (more specifically if it affects timing or overall rich/lean).
What I discovered today from stating at my datalogs was this:
1) The baro value is logged at key on (this was allready known)
2) The baro on LT1 is also reset at WOT, each and every time - what this does is take a new baro reading when WOT is acheived, but so far only under 3700rpm on mine... if your using a 2 bar tune and key on gives you ~50kpa, when you go WOT under boost I notice under certain conditions the baro will climb with the manifold MAP reading for a short period... on mine the Baro stops at about 3700rpm which is about 65kpa, however the MAP reading climbs to ~75kpa at redline as it's reading boost/manifold pressure which is approx 7psi on my setup.
This 65KPA Baro will stay there until the next WOT, which if Im under 2-3000rpm it will read whatever manifold pressure is, usually around 50-60kpa, and if kept WOT again the reading will again climb to about 65kpa and stop climing around 3700rpm.
My fueling doesnt seem to be affected, obviously this was my first concern but everything appears to be consistent from run to run. I was thinking the only problem this could/would affect would be cruise fueling since that's the only time the baro readings might vary depending what manifold pressure was the last time WOT was entered.
I do see consistend Baro increase from run to run up to 3700rpm where it stops climbing, which Im assuming if I were to run up to 100kpa the baro would still stay at 65kpa or whatever it was reading at 3700rpm.
Things I still need to prove out:
1) What affect a changing baro has on fueling - mainly for cruise since the boost/WOT area is consistent from run to run
2) How exactly the Baro system works... if in fact it stops at 3700rpm each time regardless of anything else... my thought on this is they did that on purpose to allow accurate Baro readings since below 3700rpm and WOT gives you low relative manifold airflow, which gives you near actual Baro readings since higher RPM (redline) on stock LT1 usually begins to build slight manifold vacuum due to the restrictions caused by the TB, MAF, intake air filter, etc.
3) What affect would running 15psi have on this since at 3700 the Baro may reach 75kpa by 3700rpm, which then could affect cruise fueling (probably making it a little richer? not sure) until the next low RPM WOT reset the Baro to near actual.
I havent seen any weirdness but I'm also only at 7psi. Anybody using this on higher boost please update!! mainly What effect having artifically high Baro during cruise AFTER a WOT run, compared to normal cruise after Key On but before WOT. To reset the Baro after a WOT run simply put in high gear (low RPM) and go WOT... the Baro should reset. I would expect a change in the fueling corrections but If that's the only side affect and it doesnt affect cruise driveability then I still think it's a valid solution to spending $3500 on FAST.
While I still dont see any real negative side affects from using the 2 bar setup on the LT1 PCM (still looking but I dont see any problems yet) I would like to better understand how the Baro affects the tune (more specifically if it affects timing or overall rich/lean).
What I discovered today from stating at my datalogs was this:
1) The baro value is logged at key on (this was allready known)
2) The baro on LT1 is also reset at WOT, each and every time - what this does is take a new baro reading when WOT is acheived, but so far only under 3700rpm on mine... if your using a 2 bar tune and key on gives you ~50kpa, when you go WOT under boost I notice under certain conditions the baro will climb with the manifold MAP reading for a short period... on mine the Baro stops at about 3700rpm which is about 65kpa, however the MAP reading climbs to ~75kpa at redline as it's reading boost/manifold pressure which is approx 7psi on my setup.
This 65KPA Baro will stay there until the next WOT, which if Im under 2-3000rpm it will read whatever manifold pressure is, usually around 50-60kpa, and if kept WOT again the reading will again climb to about 65kpa and stop climing around 3700rpm.
My fueling doesnt seem to be affected, obviously this was my first concern but everything appears to be consistent from run to run. I was thinking the only problem this could/would affect would be cruise fueling since that's the only time the baro readings might vary depending what manifold pressure was the last time WOT was entered.
I do see consistend Baro increase from run to run up to 3700rpm where it stops climbing, which Im assuming if I were to run up to 100kpa the baro would still stay at 65kpa or whatever it was reading at 3700rpm.
Things I still need to prove out:
1) What affect a changing baro has on fueling - mainly for cruise since the boost/WOT area is consistent from run to run
2) How exactly the Baro system works... if in fact it stops at 3700rpm each time regardless of anything else... my thought on this is they did that on purpose to allow accurate Baro readings since below 3700rpm and WOT gives you low relative manifold airflow, which gives you near actual Baro readings since higher RPM (redline) on stock LT1 usually begins to build slight manifold vacuum due to the restrictions caused by the TB, MAF, intake air filter, etc.
3) What affect would running 15psi have on this since at 3700 the Baro may reach 75kpa by 3700rpm, which then could affect cruise fueling (probably making it a little richer? not sure) until the next low RPM WOT reset the Baro to near actual.
I havent seen any weirdness but I'm also only at 7psi. Anybody using this on higher boost please update!! mainly What effect having artifically high Baro during cruise AFTER a WOT run, compared to normal cruise after Key On but before WOT. To reset the Baro after a WOT run simply put in high gear (low RPM) and go WOT... the Baro should reset. I would expect a change in the fueling corrections but If that's the only side affect and it doesnt affect cruise driveability then I still think it's a valid solution to spending $3500 on FAST.
01-19-2008, 04:35 PM
#34
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Join Date: Mar 2002
Location: Baton Rouge, LA, USA
Posts: 2,743
I'm here. However, I don't have anything to add yet.
As I was leaning out the cruise and idle AFR's, I noticed that my initial startup AFR (<2 minutes) was going too lean and started affecting driveability. I then starting looking closer at the tune and noticed that there were some odd values in the "Initial Startup AFR enrichment Vs. Coolant Temp" table that had it actually adding fuel once the engine came up to temperature. That explains the problem I was having.
I decided that I'm going to put in the correct 42 lb injector constant instead of the 30 that dookie liked for 84 lb injectors. That will require starting over on the VE and start up fuel tables. I guess I'm OCD like that, but I had to start over on the VE table anyway since I fixed the startup enrichment table.
Mike
As I was leaning out the cruise and idle AFR's, I noticed that my initial startup AFR (<2 minutes) was going too lean and started affecting driveability. I then starting looking closer at the tune and noticed that there were some odd values in the "Initial Startup AFR enrichment Vs. Coolant Temp" table that had it actually adding fuel once the engine came up to temperature. That explains the problem I was having.
I decided that I'm going to put in the correct 42 lb injector constant instead of the 30 that dookie liked for 84 lb injectors. That will require starting over on the VE and start up fuel tables. I guess I'm OCD like that, but I had to start over on the VE table anyway since I fixed the startup enrichment table.
Mike
01-29-2008, 10:15 PM
#37
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Join Date: Aug 2007
Posts: 573
Well I've been driving with the tune and still havent seen any problems... I still have to compare KEY ON BARO of ~52kpa then entering WOT above 3700rpms and see if the BARO resets to manifold vacuum (previously discussed the BARO resetting at WOT only below 3700rpm I saw recently)... but so far no problems with 7psi and under.
Im curious what will happen with a 14psi setup - this may increase the BARO so much that afterwards idle fueling will be noticably rich for cruise.. but this needs to be proved out.
More importantly if KEY ON gives 52KPA and anything over 3700 doesnt reset the BARO then if you enter WOT above 3700 will the BARO stay at 52kpa vs entering WOT at 2000rpm which for me is showing resetting the BARO up to 3700rpm (matching the manifold pressure)... if you generate considerable boost below 3700rpm then what affect would these two "ENTERING WOT MODES" do to actual AFR at WOT (if one WOT run the baro shows 52kpa vs the second WOT run shows ~65+kpa).
Really, what affect on fueling does BARO have? I think it's safe to say SO FAR 7psi and under works very good.
Someone posted a question about needing a 3bar for 15psi, I dont think so since you should be able to use the PE vs RPM tables for VE MAP ranges above 100kpa.
Im curious what will happen with a 14psi setup - this may increase the BARO so much that afterwards idle fueling will be noticably rich for cruise.. but this needs to be proved out.
More importantly if KEY ON gives 52KPA and anything over 3700 doesnt reset the BARO then if you enter WOT above 3700 will the BARO stay at 52kpa vs entering WOT at 2000rpm which for me is showing resetting the BARO up to 3700rpm (matching the manifold pressure)... if you generate considerable boost below 3700rpm then what affect would these two "ENTERING WOT MODES" do to actual AFR at WOT (if one WOT run the baro shows 52kpa vs the second WOT run shows ~65+kpa).
Really, what affect on fueling does BARO have? I think it's safe to say SO FAR 7psi and under works very good.
Someone posted a question about needing a 3bar for 15psi, I dont think so since you should be able to use the PE vs RPM tables for VE MAP ranges above 100kpa.
01-29-2008, 11:18 PM
#38
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Join Date: Jan 2002
Location: Mission, Kansas
Posts: 1,743
I do fully plan on running the 2 bar map setup and will tune it myself. I'm going to start with engineermike's tune probably(Hi Mike, I need to get an email to you) though just to make the initial startup tune good. I'll be datalogging and tuning to 15lbs for the street, and then hoping to run 18-20lbs at the shootout.
02-22-2008, 10:48 AM
#40
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Join Date: Feb 1999
Location: Yardville NJ
Posts: 70
Hey if possible could you send me a copy of your 2 bar tune?
I thought about taking advantage of the OBD2 PCM's T side 28f010 flash chip.
It's 128K but only 96K is used so you still have a blank 32K area.
Why not patch a file and create new tables in the unused area.
I got this idea from looking at Motorola AN432 that describes 128K addressing for the HC11.
I thought about taking advantage of the OBD2 PCM's T side 28f010 flash chip.
It's 128K but only 96K is used so you still have a blank 32K area.
Why not patch a file and create new tables in the unused area.
I got this idea from looking at Motorola AN432 that describes 128K addressing for the HC11.
02-22-2008, 10:10 PM
#41
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Join Date: Aug 2007
Posts: 573
Sure, send me an email address to send to.
This is a little off topic.. but "Why not patch a file and create new tables in the unused area." Im a bit confused though, if you can do all that patching and what not, why do you need my tune? If you can patch and create new tables then there's no need for my tune since it's for a mucked up 2 bar on stock 1bar PCM.
Let us know, thanks
This is a little off topic.. but "Why not patch a file and create new tables in the unused area." Im a bit confused though, if you can do all that patching and what not, why do you need my tune? If you can patch and create new tables then there's no need for my tune since it's for a mucked up 2 bar on stock 1bar PCM.
Let us know, thanks
Last edited by dookie454; 02-22-2008 at 10:25 PM.
02-23-2008, 08:30 AM
#42
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Join Date: Feb 1999
Location: Yardville NJ
Posts: 70
I can't but I'm trying to learn. I've had some free time recently and have been doing some reading.
I was thinking that it would be easier to tell the pcm to jump to some extened table in an unused spot instead of trying to move too many things around in the file.
There is plenty that I don't understand. I'll keep playing with things and maybe I'll get somewhere.
My email is cbeerman@optonline.net
I was thinking that it would be easier to tell the pcm to jump to some extened table in an unused spot instead of trying to move too many things around in the file.
There is plenty that I don't understand. I'll keep playing with things and maybe I'll get somewhere.
My email is cbeerman@optonline.net
02-23-2008, 09:42 AM
#43
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Join Date: Jan 2008
Posts: 24
Could I also get a copy of your tune? In the next month or so I'll be ready to try this out and I think with the E85 I'll be running this might be a good way to take advantage of the ability to tune the timing while in boost.
Thanks,
Dave
Guitarman03@Charter.net
Thanks,
Dave
Guitarman03@Charter.net
03-06-2008, 12:00 AM
#44
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Join Date: Aug 2007
Posts: 573
I've been thinking about another "trick" to try on the stock PCM when referencing boost. This is complicated but this may just be the trick for the one "problem" I've noticed with a 2 bar on a LT1 PCM. (the BARO reading). Also, I will test all this soon as snow/salt is off the roads.
This is a slighly different thought I had related to the BARO reading that I havent thought of before which I've been thinking about alot lately... Earlier in this discussion I posted results from one of my datamaster logs because I noticed the BARO resets at WOT under 3700rpm each time (not just at key on like the older TBI PCMs and others). For 6-7psi I dont see a problem so far.. however at 15psi Im wondering what will happen. I'd like to get this straightened out before switching pullies for 15psi.
Recap.. I start the car with my 2-bar and the Baro will stay at ~50kpa until I go WOT under 3700rpm.. now with boost in the intake I see the Baro increase to ~63kpa at 3700rpm then it stops there, doesnt increase anymore as RPM and MAP reading climbs to ~75kpa. This happens time after time when WOT entered below 3700rpm (BARO stops climbing at 3700rpm each time).
Now, this leaves the big question in my mind... if I setup fueling for BARO of 63kpa all the way to redline like I would do on a dyno or rolling from 30-50mph (starting WOT below 3700rpm) I get consistent AFR's. My questions is what would happen if I start the car, let it warm up, then lay into WOT for the first time at 90mph starting from 5000rpm (like when that new Z06 pulls up next to you and you have to start pulling where the powers's at)... well if the BARO stops climbing at 3700rpm at WOT, what if I enter WOT above 3700 without previously running WOT below and thru 3700rpms Im thinking the BARO could possibly stay at 50kpa during this 5000+RPM WOT run... and this could mean fueling could be
LEAN (since less atmosphere pressure means less airflow into cyl, meaning less fuel is needed). This could potentially be bad.
Now if the above BARO info is true which I think it is I could simply:
1) Make sure I make one WOT pull thru 3700rpm to reset BARO to ~63kpa and problem solved.. or
2) never make a WOT pull below 3700rpm (this is what I need to verify - see if the BARO stays at 50kpa if I enter WOT above 3700rpm after starting the car)
3) Setup fueling so the car wont be lean if I enter WOT above 3700rpm for first time (making 50kpa Baro) meaning if I do enter WOT below 3700rpm the fueling will be on the rich side until I enter WOT at like 1500rpms to reset BARO back to ~50kpa - but I really need to measure how much AFR is affected by this and if the BARO will in fact stay at 50kpa if I enter WOT above 3700rpms. At 6-7psi I havent noticed a a problem so far but I also have not compared Wideband readings between a WOT run with 50kpa BARO and WOT with 63kpa baro.
If this is all true then I would expect siginificant AFR changes especially at 15psi (because at 3700rpms the BARO could freeze much higher like 70-75kpa) then this could make a considerable amount of difference with fueling between 50kpa and 75kpa BARO (or method of entering WOT)... in the worst case it could be lean (if entering WOT for the first time above 3700rpms unless fueling was setup for it then it would be rich as worse case if entering WOT below 3700rpm).
Anyway.... with all that said.. my thought on how to avoid any of this from happening (different BARO readings above 3700rpm depending when you entered WOT) is something like this:
1) Disable Closed Loop and run purley SD in open Loop (to stop fueling correction) and allow fueling control strictly from the VE tables... BARO will still be affected without help from the next step,
2) Disable PE (WOT) mode totally somehow (%TPS for WOT = only 99%) and run purely off of the VE tables (my PE enrichement is set to 0 anyway).. since hopefully you will always be out of "PE/WOT" (assuming you could turn that off completely) the BARO should never reset until the next Key On which is perfect. The alternative would be entering 0% TPS for WOT but then the BARO will constantly reset and hold whatever MAP was seen at 3700rpm.
Anybody with serious thoughts on this please chim in! Anybody running 0% PE mode at WOT please chim in since you could say how to do that?
And yes, if we could modify the PCM or add any one of these controls to LT1_Edit OR Tunercats this could really fix all the problems
1) Lock BARO to reset only at Key On and not at WOT (like older PCMs)
2) Completely disable entering PE/WOT MODE (99% TPS is all I see)
3) Enable 2 bar MAP (obviously) (this would automatically mean the Baro would be locked to Key On only OR a seperate sensor would be used for Baro readings)
This is a slighly different thought I had related to the BARO reading that I havent thought of before which I've been thinking about alot lately... Earlier in this discussion I posted results from one of my datamaster logs because I noticed the BARO resets at WOT under 3700rpm each time (not just at key on like the older TBI PCMs and others). For 6-7psi I dont see a problem so far.. however at 15psi Im wondering what will happen. I'd like to get this straightened out before switching pullies for 15psi.
Recap.. I start the car with my 2-bar and the Baro will stay at ~50kpa until I go WOT under 3700rpm.. now with boost in the intake I see the Baro increase to ~63kpa at 3700rpm then it stops there, doesnt increase anymore as RPM and MAP reading climbs to ~75kpa. This happens time after time when WOT entered below 3700rpm (BARO stops climbing at 3700rpm each time).
Now, this leaves the big question in my mind... if I setup fueling for BARO of 63kpa all the way to redline like I would do on a dyno or rolling from 30-50mph (starting WOT below 3700rpm) I get consistent AFR's. My questions is what would happen if I start the car, let it warm up, then lay into WOT for the first time at 90mph starting from 5000rpm (like when that new Z06 pulls up next to you and you have to start pulling where the powers's at)... well if the BARO stops climbing at 3700rpm at WOT, what if I enter WOT above 3700 without previously running WOT below and thru 3700rpms Im thinking the BARO could possibly stay at 50kpa during this 5000+RPM WOT run... and this could mean fueling could be
LEAN (since less atmosphere pressure means less airflow into cyl, meaning less fuel is needed). This could potentially be bad.Now if the above BARO info is true which I think it is I could simply:
1) Make sure I make one WOT pull thru 3700rpm to reset BARO to ~63kpa and problem solved.. or
2) never make a WOT pull below 3700rpm (this is what I need to verify - see if the BARO stays at 50kpa if I enter WOT above 3700rpm after starting the car)
3) Setup fueling so the car wont be lean if I enter WOT above 3700rpm for first time (making 50kpa Baro) meaning if I do enter WOT below 3700rpm the fueling will be on the rich side until I enter WOT at like 1500rpms to reset BARO back to ~50kpa - but I really need to measure how much AFR is affected by this and if the BARO will in fact stay at 50kpa if I enter WOT above 3700rpms. At 6-7psi I havent noticed a a problem so far but I also have not compared Wideband readings between a WOT run with 50kpa BARO and WOT with 63kpa baro.
If this is all true then I would expect siginificant AFR changes especially at 15psi (because at 3700rpms the BARO could freeze much higher like 70-75kpa) then this could make a considerable amount of difference with fueling between 50kpa and 75kpa BARO (or method of entering WOT)... in the worst case it could be lean (if entering WOT for the first time above 3700rpms unless fueling was setup for it then it would be rich as worse case if entering WOT below 3700rpm).
Anyway.... with all that said.. my thought on how to avoid any of this from happening (different BARO readings above 3700rpm depending when you entered WOT) is something like this:
1) Disable Closed Loop and run purley SD in open Loop (to stop fueling correction) and allow fueling control strictly from the VE tables... BARO will still be affected without help from the next step,
2) Disable PE (WOT) mode totally somehow (%TPS for WOT = only 99%) and run purely off of the VE tables (my PE enrichement is set to 0 anyway).. since hopefully you will always be out of "PE/WOT" (assuming you could turn that off completely) the BARO should never reset until the next Key On which is perfect. The alternative would be entering 0% TPS for WOT but then the BARO will constantly reset and hold whatever MAP was seen at 3700rpm.
Anybody with serious thoughts on this please chim in! Anybody running 0% PE mode at WOT please chim in since you could say how to do that?
And yes, if we could modify the PCM or add any one of these controls to LT1_Edit OR Tunercats this could really fix all the problems
1) Lock BARO to reset only at Key On and not at WOT (like older PCMs)
2) Completely disable entering PE/WOT MODE (99% TPS is all I see)
3) Enable 2 bar MAP (obviously) (this would automatically mean the Baro would be locked to Key On only OR a seperate sensor would be used for Baro readings)
Last edited by dookie454; 03-06-2008 at 12:17 AM.