MAF's
04-24-2006, 04:01 AM
#3
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If you go MAFless then you'll need an SD Tune, these are often easier with highly tuned setups as they actually work with less information/data due to not having a MAF this in turn makes it easier. However due to not having a MAF you will need to tune for every induction/exhuast mod as the PCM will not be able to automatically adjust in the same way as when using a MAF. This is the same issue the guys with the new "Hemi's" are having as they use SD setups from the factory, but even a CAI/catback really needs a tune.
04-24-2006, 08:35 AM
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Originally Posted by 300bhp/ton
If you go MAFless then you'll need an SD Tune, these are often easier with highly tuned setups as they actually work with less information/data due to not having a MAF this in turn makes it easier. However due to not having a MAF you will need to tune for every induction/exhuast mod as the PCM will not be able to automatically adjust in the same way as when using a MAF. This is the same issue the guys with the new "Hemi's" are having as they use SD setups from the factory, but even a CAI/catback really needs a tune.
Thanks for that info!
Do you know if a SD tune will cost me more money vs a regular tune?
I want to get everything tuned at once after I get my H/C setup on!
04-24-2006, 09:14 AM
#7
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Originally Posted by wakerider017
Thanks for that info!
Do you know if a SD tune will cost me more money vs a regular tune?
I want to get everything tuned at once after I get my H/C setup on!
Do you know if a SD tune will cost me more money vs a regular tune?
I want to get everything tuned at once after I get my H/C setup on!
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04-24-2006, 09:50 AM
#8
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Originally Posted by Steel Chicken
there is no reason to ditch the MAF unless you are making huge power or your tuner is too lazy to recalibrate it.
Most of them are mafless and it seems like it would be hard to shove a MAF in there...
Here is a pic of what I am talking about:
If that can be done for the right price I think I will buy one... What do you think?
04-24-2006, 09:57 AM
#9
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If you replace the MAF with a pipe/hose, there will be less restriction, but you will lose the abililty to slide between the high and low octane spark tables (i.e. this form of SD runs off the low octane table, so you copy the high to the low), unless you run a custom operating system.
In SD the AFR is determined by the OLFA and PE tables.
You can run OLSD or CLSD; in CLSD it uses narrowband to trim to 14.63 and will goto the OLFA/PE tables when the throttle is opened sufficiently to enter OL/PE.
One advantage is that you can dial in the exact AFR that you want (wideband AFR exactly equals commanded AFR).
Another advantage is that VE/OLFA/PE table lookup is pretty much instant, whereas MAF input has finite time lag.
Another advantage is that an over-oiled K+N air filter won't foul a non-existant MAF.
Of course the point to all this is, if you had tuning software you could tailor all of this to personal taste on a daily basis.
BTW: Look in the PCM tuning section to see more comments regarding running around MAF-less.
In SD the AFR is determined by the OLFA and PE tables.
You can run OLSD or CLSD; in CLSD it uses narrowband to trim to 14.63 and will goto the OLFA/PE tables when the throttle is opened sufficiently to enter OL/PE.
One advantage is that you can dial in the exact AFR that you want (wideband AFR exactly equals commanded AFR).
Another advantage is that VE/OLFA/PE table lookup is pretty much instant, whereas MAF input has finite time lag.
Another advantage is that an over-oiled K+N air filter won't foul a non-existant MAF.
Of course the point to all this is, if you had tuning software you could tailor all of this to personal taste on a daily basis.
BTW: Look in the PCM tuning section to see more comments regarding running around MAF-less.
04-24-2006, 12:59 PM
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I like the ORSSOM one a lot!
I plan on install a fast 90 down the road... (I have heard the Fast 90 is 1" longer than stock...)
I wonder if this will still fit after that?
I plan on install a fast 90 down the road... (I have heard the Fast 90 is 1" longer than stock...)
I wonder if this will still fit after that?
04-24-2006, 05:34 PM
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I took an SD tune into account for a span of time, then kept the larger MAF because it was what was on the car at the moment.
However, I hear that there are certain parameters that are more difficult to tune and other parameters that are better left to one form of tune or the other, not sure which would be most applicable to the situation, that a tuner can differentiate from the various methods, and best apply the strategy of the form of tune that is there.
However, I hear that there are certain parameters that are more difficult to tune and other parameters that are better left to one form of tune or the other, not sure which would be most applicable to the situation, that a tuner can differentiate from the various methods, and best apply the strategy of the form of tune that is there.
04-25-2006, 05:09 AM
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Originally Posted by 300bhp/ton
If you go MAFless then you'll need an SD Tune, these are often easier with highly tuned setups as they actually work with less information/data due to not having a MAF this in turn makes it easier. However due to not having a MAF you will need to tune for every induction/exhuast mod as the PCM will not be able to automatically adjust in the same way as when using a MAF. This is the same issue the guys with the new "Hemi's" are having as they use SD setups from the factory, but even a CAI/catback really needs a tune.
Where did you get that idea?
Any change to the induction tract (from the cam all the way back to the air filter) "techinically" requires recalibration of both the VE and MAF tables. The PCM compensates for minor changes via fuel trims, ie Closed Loop.
04-25-2006, 06:00 AM
#15
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Originally Posted by TAQuickness
Where did you get that idea?
Any change to the induction tract (from the cam all the way back to the air filter) "techinically" requires recalibration of both the VE and MAF tables. The PCM compensates for minor changes via fuel trims, ie Closed Loop.
Any change to the induction tract (from the cam all the way back to the air filter) "techinically" requires recalibration of both the VE and MAF tables. The PCM compensates for minor changes via fuel trims, ie Closed Loop.
Originally Posted by David Vizard (Popular Hot Rodding - Engine Masters)
Unlike an LS6, which has a mass air system that allows the computer to adjust the fuel flow for any given airflow so that the mixture is always right (theoretically at least), the Hemi has a speed density system. This means that any increase in airflow into the engine goes unseen by the rest of the system. If a modification is done that increases mass airflow, such as a cold-air package, the computer has to be reprogrammed accordingly.
04-25-2006, 09:43 AM
#16
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For example, changing cam will change reversion/resonance in the intake tract which causes the MAF to "misread" so a new MAF table will be required (or MAF can be tossed).
04-25-2006, 01:11 PM
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Originally Posted by joecar
For example, changing cam will change reversion/resonance in the intake tract which causes the MAF to "misread" so a new MAF table will be required (or MAF can be tossed).
04-25-2006, 01:40 PM
#19
Ive got my open loop speed density tune dialed in pretty well, but my fueling is never as accurate as when im running my maf. I know mine's not a restriction since ive hogged it out an extra 40%. Youve got a bigger maf with the ls2. Id keep the MAF if at all possible, but thats just my opinion.
04-25-2006, 03:29 PM
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Originally Posted by 300bhp/ton
Originally Posted by David Vizard (Popular Hot Rodding - Engine Masters)
Unlike an LS6, which has a mass air system that allows the computer to adjust the fuel flow for any given airflow so that the mixture is always right (theoretically at least), the Hemi has a speed density system. This means that any increase in airflow into the engine goes unseen by the rest of the system. If a modification is done that increases mass airflow, such as a cold-air package, the computer has to be reprogrammed accordingly.
