381cu in stroker - tunercat newB.
10-21-2005, 12:19 AM
#1
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Location: West Plains, MO
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381cu in stroker - tunercat newB.
This is my first venture into tuning factory PCM's, I've done MegaSquirt with very good success, but this is new to me. A few questions.
So how does the 95 LT1 PCM use the VE vs RPM vs MAP tables and the MAF calibration tables together?
do I need to tune one of them, both of them?
i downloaded some stroker bins and i noticed that they set volume to 717cc's in the constants, thats 5.7L Do people leave this setting stock and then add fuel at the VE tables? or maf calibration????
will descreening the maf effect much? i've got a k&n directly infront of the MAF on my LT1 installed in my 67 chevy pickup.
could I take a tuned 5.7L hot cam bin, change the volume constant for my 381 cu in motor and be good to go?
So how does the 95 LT1 PCM use the VE vs RPM vs MAP tables and the MAF calibration tables together?
do I need to tune one of them, both of them?
i downloaded some stroker bins and i noticed that they set volume to 717cc's in the constants, thats 5.7L Do people leave this setting stock and then add fuel at the VE tables? or maf calibration????
will descreening the maf effect much? i've got a k&n directly infront of the MAF on my LT1 installed in my 67 chevy pickup.
could I take a tuned 5.7L hot cam bin, change the volume constant for my 381 cu in motor and be good to go?
10-21-2005, 05:48 AM
#2
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Location: Balt/Gaith., MD
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Re: 381cu in stroker - tunercat newB.
here's my $.02 ... letting the computer know how much the engine disp. is would help it know how much fuel to add. (per volume of air) the Volumetric Efficiency (VE) tables tell it how efficient it has to be compared to the ideal engine (perfect 14.7?). I've done some (not much) tuning using both the VE tables and MAF tables and also only using the VE tables. I've noticed that if you don't change the MAF tables, you usually have to add less in the VE tables, but then all you're doing is tricking the engine into thinking it's doing the right thing but adding more fuel than it has to (theoretically) so it satisfies your needs. The best bet would be to tune all the tables 'cos in essence, all of the original parameters have changed with your new setup anyway and it'll be more accurate ... someone please chime in if I'm completely wrong!
Last edited by Mean Green Z28; 10-21-2005 at 05:50 AM.
10-21-2005, 06:19 PM
#3
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Re: 381cu in stroker - tunercat newB.
My experience,
Forget the VE tables. They are only used in the event of a MAF sensor failure. Set your idle and part throttle fueling by using the proper cylinder size, proper injector constant, and then tweek the MAF tables to get BLMs close to 128 in all idle and cruise cells. Once that is taken care of, head to the dyno and set up the PE vs RPM table to get a 12.5 to 13 AFR at WOT for an NA setup. Working on VE tables on a Mass Air LT1 is getting you nothing. This topic is a bit controversial and I'm sure I'll probably get flamed. Just my O2.
Steve
Forget the VE tables. They are only used in the event of a MAF sensor failure. Set your idle and part throttle fueling by using the proper cylinder size, proper injector constant, and then tweek the MAF tables to get BLMs close to 128 in all idle and cruise cells. Once that is taken care of, head to the dyno and set up the PE vs RPM table to get a 12.5 to 13 AFR at WOT for an NA setup. Working on VE tables on a Mass Air LT1 is getting you nothing. This topic is a bit controversial and I'm sure I'll probably get flamed. Just my O2.
Steve
10-21-2005, 11:18 PM
#4
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Location: Balt/Gaith., MD
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Re: 381cu in stroker - tunercat newB.
Originally Posted by SABLT194
My experience,
Forget the VE tables. They are only used in the event of a MAF sensor failure. Set your idle and part throttle fueling by using the proper cylinder size, proper injector constant, and then tweek the MAF tables to get BLMs close to 128 in all idle and cruise cells. Once that is taken care of, head to the dyno and set up the PE vs RPM table to get a 12.5 to 13 AFR at WOT for an NA setup. Working on VE tables on a Mass Air LT1 is getting you nothing. This topic is a bit controversial and I'm sure I'll probably get flamed. Just my O2.
Steve
Forget the VE tables. They are only used in the event of a MAF sensor failure. Set your idle and part throttle fueling by using the proper cylinder size, proper injector constant, and then tweek the MAF tables to get BLMs close to 128 in all idle and cruise cells. Once that is taken care of, head to the dyno and set up the PE vs RPM table to get a 12.5 to 13 AFR at WOT for an NA setup. Working on VE tables on a Mass Air LT1 is getting you nothing. This topic is a bit controversial and I'm sure I'll probably get flamed. Just my O2.
Steve
BTW, there is no PE table in TunerCat, it's just called WOT
10-22-2005, 05:26 AM
#5
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Re: 381cu in stroker - tunercat newB.
For reference reading:
http://web.camaross.com/forums/showthread.php?t=191263
Christian Millard did multiple tests on a ODB1 car. He actually zero'd out the VE table and found no diferences in BLM's when the MAF was plugged in. I beleive he went on to the hack the code far enough to prove the point. BTW, before he started the tests, he believed,as others at that time, that the MAF and VE worked together to adjust part throttle fueling. ODBII may be different so I won't speak to that.
Steve
http://web.camaross.com/forums/showthread.php?t=191263
Christian Millard did multiple tests on a ODB1 car. He actually zero'd out the VE table and found no diferences in BLM's when the MAF was plugged in. I beleive he went on to the hack the code far enough to prove the point. BTW, before he started the tests, he believed,as others at that time, that the MAF and VE worked together to adjust part throttle fueling. ODBII may be different so I won't speak to that.
Steve
Last edited by SABLT194; 10-22-2005 at 05:33 AM.
10-22-2005, 12:06 PM
#6
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Re: 381cu in stroker - tunercat newB.
maybe i'll disable MAF and go with speed density ve tables like i'm used to.
where is the PE tables in tunercat..i cant find them..are they labled different?
thanks
Brendan.
where is the PE tables in tunercat..i cant find them..are they labled different?
thanks
Brendan.
10-22-2005, 12:08 PM
#7
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Location: Kansas
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Re: 381cu in stroker - tunercat newB.
Originally Posted by Mean Green Z28
I don't know about that bro. 'cos the VE tables are the main fueling tables. playing with the MAF only tricks the engine into believing it's getting more air, so it dumps more fuel. Theoretically, the air going through the MAF is the same for the hz. it's reading nomatter what you do to your engine. I believe you've gotta tune all 3 to get the perfect tune at all MAP readings and WOT.
BTW, there is no PE table in TunerCat, it's just called WOT
BTW, there is no PE table in TunerCat, it's just called WOT
10-23-2005, 04:56 AM
#8
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Re: 381cu in stroker - tunercat newB.
Yeah, that's what I meant when I said WOT.
If you can tune the car in SD mode, why does the car shut off when the MAF is disconnected? Doesn't start with it disconnected either! Is there something the tables that I should change to keep the car in just SD mode and not go into the MAF tables?
If you can tune the car in SD mode, why does the car shut off when the MAF is disconnected? Doesn't start with it disconnected either! Is there something the tables that I should change to keep the car in just SD mode and not go into the MAF tables?
10-23-2005, 05:22 AM
#9
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Re: 381cu in stroker - tunercat newB.
In Tunercat
Click Tables
Click ECM Switch Table
Click Speed Density Mode enable
Have you changed your cylinder size for the 381 CID? Have you changed your injector constant to match the flow rate of your injectors? Your car should start and run with the MAF just unplugged unless you have a gawdaweful cam. You would get a SES light and it would run in SD mode. Assuming your using stock VE tables, the ECM will probably pull fuel like crazy at idle and low load and rpm ranges. ECM will need to add fuel when you get into the peak torque ranges (4500-5500 rpm and higher MAP).
I'm surprised it didn't start and run.
Steve
Click Tables
Click ECM Switch Table
Click Speed Density Mode enable
Have you changed your cylinder size for the 381 CID? Have you changed your injector constant to match the flow rate of your injectors? Your car should start and run with the MAF just unplugged unless you have a gawdaweful cam. You would get a SES light and it would run in SD mode. Assuming your using stock VE tables, the ECM will probably pull fuel like crazy at idle and low load and rpm ranges. ECM will need to add fuel when you get into the peak torque ranges (4500-5500 rpm and higher MAP).
I'm surprised it didn't start and run.
Steve
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