Hello t00ners! New to LS1, have basic PCM operations question..
03-23-2005, 10:26 AM
#1
Hello t00ners! New to LS1, have basic PCM operations question.. Hey guys, I'm new to the LS1 world ('00 WS6) and I was looking forward to learning a whole new platform upon which to tune. Now I'm no professional by trade, I'm a hobbyist tuner in the Honda world, familiar with programs such as Hondata, Uberdata, Crome, along with the usual AFC and GReddy E-manage piggyback systems though I really wouldn't call that tuning per-se.
Anyways, like I said I'm particularly familiar with Honda-software based systems with regards to timing and fuel managment, I've never tinkered with LS1/GM software though but I'd like to get a feel for the basic functions of the system.
I presume that GM systems operate on the closed loop / open loop system like so many others do yes? Therefore regardless of A/F as measured by the stock NB02, the ECU will run the pre-determined fuel/timing maps according to the rev/pressure scale during WOT operation correct? Likewise it will operate with constant trim/enrichment during part throttle operation to keep A/F's at stoich during closed loop operation yes? If anybody esle has used speed density based systems, how does tuning with MAF's differ aside from obvious terminology? Any other tips with regards to the LS1 specificlaly?
I just DL'd the entire 'PCM Tuning Process Flow' document hosted here and I'll be giving that some reading, looking forward to purchasing HPTuners software for my car soon as well so I can get some hands on experience. Thanks for the help guys, and don't mind the n00b questions too much, I'm a quick learner
Anyways, like I said I'm particularly familiar with Honda-software based systems with regards to timing and fuel managment, I've never tinkered with LS1/GM software though but I'd like to get a feel for the basic functions of the system.
I presume that GM systems operate on the closed loop / open loop system like so many others do yes? Therefore regardless of A/F as measured by the stock NB02, the ECU will run the pre-determined fuel/timing maps according to the rev/pressure scale during WOT operation correct? Likewise it will operate with constant trim/enrichment during part throttle operation to keep A/F's at stoich during closed loop operation yes? If anybody esle has used speed density based systems, how does tuning with MAF's differ aside from obvious terminology? Any other tips with regards to the LS1 specificlaly?
I just DL'd the entire 'PCM Tuning Process Flow' document hosted here and I'll be giving that some reading, looking forward to purchasing HPTuners software for my car soon as well so I can get some hands on experience. Thanks for the help guys, and don't mind the n00b questions too much, I'm a quick learner
03-23-2005, 10:48 AM
#2
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The LS1 PCM will make fuel trim at WOT operation.
That fact makes it that much more important to get the VE and MAF tables correct.
It uses a combination of VE table (MAP), and input from the MAF to determine fueling, then applies corrections as in fuel trims... LTFTs for long-term learned trims, and STFT's for short term. After making corrections/tuning changes it helps to zero the LTFTs and then give some driving time for the PCM to relearn to see where you're at.
I think it uses fuel trims in both open and closed loop, but only runs stoich and updates the LTFTs when in closed loop.
IMO, the trims applied in open loop and WOT are what I would call blind fueling corrections, so as with most corrections are not always right where you want them.
As with the other systems, the PCM will work against you in closed loop because it assumes a factory stock engine with all working emissions equipment in place. You can get a highly modified engine surprisingly close in most cases tuning with closed loop operation in effect, but some cases will require open-loop tuning and/or running in SD mode by removing the MAF and O2's.
I'm not the expert here either, but I thought this would give you an idea of where you're at.
That fact makes it that much more important to get the VE and MAF tables correct.
It uses a combination of VE table (MAP), and input from the MAF to determine fueling, then applies corrections as in fuel trims... LTFTs for long-term learned trims, and STFT's for short term. After making corrections/tuning changes it helps to zero the LTFTs and then give some driving time for the PCM to relearn to see where you're at.
I think it uses fuel trims in both open and closed loop, but only runs stoich and updates the LTFTs when in closed loop.
IMO, the trims applied in open loop and WOT are what I would call blind fueling corrections, so as with most corrections are not always right where you want them.
As with the other systems, the PCM will work against you in closed loop because it assumes a factory stock engine with all working emissions equipment in place. You can get a highly modified engine surprisingly close in most cases tuning with closed loop operation in effect, but some cases will require open-loop tuning and/or running in SD mode by removing the MAF and O2's.
I'm not the expert here either, but I thought this would give you an idea of where you're at.
