Mass Air vs Speed Density
03-02-2010, 04:55 PM
#21
i wont comment on the previous tuner, but regardless, i need something. i know some drivability issues are to be expected with an MS4 cam, but seriously, ive talked to people who say it drives like stock except for the insane power and hard chop.
03-02-2010, 07:24 PM
#23
Sounds like your tuner only tuned for WOT. I still say that Frost can help you & without a dyno. May want to @ least shoot him a PM & discuss a little.
03-02-2010, 08:01 PM
#24
Yah, I would say that there would be no driveability issues. My self tune, aided by LS1Tech & EFILive forum members, idles great, fires right up & drives normally. Only issue I have is not tune related; play in the independent rear suspension splines.
Sounds like your tuner only tuned for WOT. I still say that Frost can help you & without a dyno. May want to @ least shoot him a PM & discuss a little.
Sounds like your tuner only tuned for WOT. I still say that Frost can help you & without a dyno. May want to @ least shoot him a PM & discuss a little.
03-03-2010, 07:40 AM
#25
Drivin year-round SDOL. I have not touched the tune since June, it is has been as low as 5* here and no trouble. Not dead on but close enough to keep fuel economy and hp consistent.
5.3 LM7 224 cam, 60e. Idles like a dream at 615rpm (58-60kpa), never a stumble.
5.3 LM7 224 cam, 60e. Idles like a dream at 615rpm (58-60kpa), never a stumble.
03-03-2010, 09:01 AM
#27
Really, there should never be a 'vs' debate.
Depending on your power goals, you can do either. Especially, if you are running closed-loop. Sometimes Trims actually line up better with CLSD, but ultimately if you are getting the AFR you want (both stoich and PE), you do not need to pit the two against each other.
Tune both properly and you will be happy. You will have proper transitional fueling and in the event your MAF fails, life will be good. MAF may require a little more work (resolution-wise), but it does not have to be a 'one or the other mentality'.
Depending on your power goals, you can do either. Especially, if you are running closed-loop. Sometimes Trims actually line up better with CLSD, but ultimately if you are getting the AFR you want (both stoich and PE), you do not need to pit the two against each other.
Tune both properly and you will be happy. You will have proper transitional fueling and in the event your MAF fails, life will be good. MAF may require a little more work (resolution-wise), but it does not have to be a 'one or the other mentality'.
A properly calibrated car, can run around in open loop just fine in pretty much any weather condition...closed loop should really be used to account for changes in fuel from station to station, and other things that we can't measure with the car on the input side...so instead we measure it with the output side and make changes accordingly...granted, sensors aren't perfect, and over time they don't read exactly the same as they used to in a given circumstance, and closed loop is there to correct for that too.
That said...I have a leaky exhaust manifold (and a set of headers sitting here waiting for me to have time to install them).
I spent a LOT of time getting my cars tune as accurate as I could in speed density a year or more ago, haven't done much to the tune since, other than adjust the speedometer for different tires, make a few minor tweaks here and there...anyways, I decided to plug in the HPTuners cable last night, and noted that the left bank is adding a stupid amount of fuel due to the exhaust leak...but the right bank was right where I expected to see it (within a couple % everywhere)...so I said "screw this" and disabled closed loop and reset my fuel trim data. It's a band aid for now...I need to fix my exhaust, and I will ASAP...but it will get me through the rest of this week driving to work (150 miles a day regardless of weather) without wasting fuel on making the left bank stupidly rich. The car felt great this morning...no issues with the open loop tune, feels as strong a it should under heavy throttle (though the road is wet because of flurries so I really couldn't go too nuts on the throttle).
MAF or SD are equally capable...the people who knock SD are the people who don't know how to calibrate it properly, and the people who knock MAF's are usually the ones trying to make a very high amount of horsepower through a stock MAF thats not capable of measuring that much air, or with a computer that has issues with either reading the higher MAF frequency, or have a hard limit of X grams/second (I think 512?)...but if the tuner knows what they're doing, both MAF and SD are both equally valid means of tuning a vehicle, so long as the vehicles sensors are equipped for the airflow the engine could see, and so long as the vehicles computer has the correct equations and tables inside of it to allow for proper calibration in that mode.
03-03-2010, 09:57 AM
#29
closed loop should really be used to account for changes in fuel from station to station, and other things that we can't measure with the car on the input side...so instead we measure it with the output side and make changes accordingly...granted, sensors aren't perfect, and over time they don't read exactly the same as they used to in a given circumstance, and closed loop is there to correct for that too.
It is more beneficial to the engine to operate at or near stoich, but the whole premise of alternating above and below stoich, is to keep the CATs full of oxygen and working correctly. They don't like it when the engine runs for too long either above or below stoich. Lean cruise for instance. Good for mileage, not so good for CATs.
03-03-2010, 10:29 AM
#30
In a nutshell, CL is a part of making the CATs work correctly. They require an alternating rich lean rich lean condition to keep the oxygen level up in them. [Above stoich, oxidation, below stoich, reduction.]
It is more beneficial to the engine to operate at or near stoich, but the whole premise of alternating above and below stoich, is to keep the CATs full of oxygen and working correctly. They don't like it when the engine runs for too long either above or below stoich. Lean cruise for instance. Good for mileage, not so good for CATs.
It is more beneficial to the engine to operate at or near stoich, but the whole premise of alternating above and below stoich, is to keep the CATs full of oxygen and working correctly. They don't like it when the engine runs for too long either above or below stoich. Lean cruise for instance. Good for mileage, not so good for CATs.
Ever toss a scope on a servo in a CNC machine? It's pretty cool.
03-07-2010, 11:30 AM
#33
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From quickly reading through this post I get SD will not keep up as well with temperature changes like a maf system will...meaning spraying as much as I do will be an absolute NO-GO!
In SC in the last month the temperature has been in the 20's at night and is around 65 or so right now. It could easily change 35+ degrees in a day. All of my power is added post-maf so would it be better to run a maf on mine? It sounds like a never-ending problem, I eventually will change to a turbo setup so I'm going to have to change an SD tune at sea level 75 degrees here to high altitude 30 degrees in Colorado?
I'm a tuning newbie so If I'm wrong please let me know...
In SC in the last month the temperature has been in the 20's at night and is around 65 or so right now. It could easily change 35+ degrees in a day. All of my power is added post-maf so would it be better to run a maf on mine? It sounds like a never-ending problem, I eventually will change to a turbo setup so I'm going to have to change an SD tune at sea level 75 degrees here to high altitude 30 degrees in Colorado?
I'm a tuning newbie so If I'm wrong please let me know...
03-07-2010, 11:50 AM
#34
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Some of those SD Temperature problems were related to open-loop tunes in the early days. Today, with custom OS's and/or even a closed-loop SD tune..the problem does not really exist.
But, as stated before a MAF tune is doable until your airflow requirements exceed the physical limits of the MAF.
There are peculiarities, pluses and minuses to each system. In the U.S., even a MAF car uses SD at low airflow and transitional fueling. Ideally tuning both for maximum performance will make you and your car the happiest..
But, as stated before a MAF tune is doable until your airflow requirements exceed the physical limits of the MAF.
There are peculiarities, pluses and minuses to each system. In the U.S., even a MAF car uses SD at low airflow and transitional fueling. Ideally tuning both for maximum performance will make you and your car the happiest..
03-07-2010, 03:35 PM
#36
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Make the trip for a dyno tune, with it being cammed with an MS4, there is no way a mail order tune would be sufficient.
03-08-2010, 09:58 AM
#37
GM does...the new cartridge style MAF, if you put it in a larger diameter pipe, and calibrate the PCM accordingly. The problem is, depending on which car you have, and thus which PCM it has, regardless of the physical limit of the MAF, there are also limits of the PCM regarding how much air they can actually measure from the MAF...regardless of the MAF itself. In some cases it's 512 grams per second...which is not really all that ridiculous in some setups...in other cases it's much higher. If you're not exceeding either the MAF or the PCM's thresholds...a MAF is a great option, it's a great sensor, and it's not hard to tune either...if you are exceeding them, SD is the way to go...if you have another requirement, like a swap in a hot rod, and you want a simplified air intake without a sensor in it or something of that nature, SD works great there too, even at stock power levels.
