2 bar map sensor..what does it take
The stock MAF is only good to manage up to 14 lbs of boost, this being it's threshold of an accurate reading. He recommended not going over 13 lbs of boost on a MAF tune. It costs nearly twice as much to do the SD tune on my car, and I'm not going to be boosting over 13 lbs for a while so I'm planning on tuning the car with a MAF to start with due to cost and my puny converter/tranny that's in the car currently. I'm going for about 8 lbs of boost to start so a MAF tune will be fine. When I get a th-400 in the car and a 9" or 12 bolt rear and I'm ready to go all out with it, I'm going to max the MAF, see how it does, then possibly go SD with it.
I will proably turn up the boost even more if I can keep the heads down
I will proably turn up the boost even more if I can keep the heads down
"the problem is when you have any kind of a temp change it will affect your tune because theres no sensors being used to adapt to air flow, temp and pressure changes AKA your MAF"
Which is totally untrue. You do lose the MAF which actually measures airflow, but there are still sensors that measure temp (IAT) and pressure (MAP) which are used to calculate airflow.
Yup, what he says....
To make a 2 bar work with a 1 bar OS on something like a LT1 there some top secret **** that needs to be done.
Without giving away too much stuff, do a search on camaroz28 and you'll find most of the info. Be warned, its difficult to get right, and its not something you want to be trying as your first tune.
To make a 2 bar work with a 1 bar OS on something like a LT1 there some top secret **** that needs to be done.
Without giving away too much stuff, do a search on camaroz28 and you'll find most of the info. Be warned, its difficult to get right, and its not something you want to be trying as your first tune.
I am talking about an LT1...Done it time and time again, but as you say, You need to know what you are doing.......Mine, 95 2 Bar Map, 12lbs 648 RWHP DD,Pump Gas, AC and all.......14lbs 722 RWHP Fast Gas.
To make a 2 bar work with a 1 bar OS on something like a LT1 there some top secret **** that needs to be done.
Without giving away too much stuff, do a search on camaroz28 and you'll find most of the info. Be warned, its difficult to get right, and its not something you want to be trying as your first tune.
Dang you and Moe beat me to the punch.... I was reading all of the HPT custom OS crap wondering how they all missed the fact that it was an Lt1.
I know what WILL come in handy when doing the tune.... a spreadsheet to track what you are doing inside of the PCM or at least a notebook... some way to keep up with the table trickery
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The good part about voltage based MAF's that it's easy to multiply/divide voltage. frequency based MAFs are more precise, but the whole idea of multiplying/dividing the range goes out of the window, unless you figure out a circuit that can multiply frequencies.
the reason why some cars deal with a lot of power on MAF is the voltage trick. for example, if your MAF describes 500g/sec at 5volts, and at that moment you'll be doing 20ms pulse width on your Xg/sec flowing injectors, you can cut the MAF voltage in two, while sizing your injectors to flow 2*X.
so at 2.5v computer thinks you're flowing 250g/sec of air, which needs X/2g/sec of fuel. but in reality you are flowing 500g/sec at 2.5v, and your injectors are dumping twice what X/2 would be, which is X. so you're back to the same air/fuel amounts (500g/sec and X fuel, just like in the starting case) but at 2.5 volts, not 5.
this way at 5v computer thinks that it's flowing 500g/sec and needs X fuel. in reality it's flowing 1000g/sec of airflow, and injectors will dump 2*X fuel, keeping AFR the same. so you end up with twice the range on the same voltage range.
this theory goes out the window when things go nonlinear, and since very few things in reality are linear, this method is plagued with assumptions and fudge factors. in the end to have a proper tune you'd have to make up for the imprecision somewhere else, and that's why i'd rather do things right from the getgo--if both methods will ultimately take the same amount of work, but one of them is going to be working off wrong numbers, might as well do it proper.
The 2/3 bar Custom Operating systems way of doing it:
* Low cost (2) credits from HPTuners & the price of a 2 or 3 bar Map sensor to be up and running
* Full use of both the High & Low Octane tables even with no maf sensor in place
* Real Time Tuning Available(Most Calibrations)
* Extends VE table from 105 kpa all the way to either 210kpa or 315kpa for LS1 applications
* Adds a boost enrichment table for different boost levels-this is great when you want to run 6psi on the street but 10psi at the track as you can set your boost enrichment table to add a bit more fuel for that 10psi setting without the need to reflash again for the changes.
Disadvantages of using MAF in boosted applications
* Your fueling will be completely wrong under many conditions because once you max the maf table the computer looks to the other fueling tables & pretty much is just guessing at that point. Fueling isnt always just rpm dependant so when you've only got 1 wot fueling table(power enrichement) which is done by rpm only your basically guessing at what # to put in. This also limits you in the fact that you can't have variable boost levels...once the maf maxes it maxes but you've only got one pe table thats only rpm dependant rather then boost dependant so if your commanding 11.5:1 at 5500 rpms on 5psi its still going to command 11.5:1 at 5500 on 10psi yet your flowing a ton more air at that point meaning your going to go leaner at 10psi more than likely.
* Unless you opt for the MAF RTT custom 1 bar OS you probably don't have access to Real Time Tuning and if you did consider the 1 bar maf OS your only now 1 credit from the 2 bar custom SD OS and doing it the right way.
* No way to change boost levels without reflashing in a different tune
Take your pick.
Last edited by MFIC; Mar 11, 2008 at 12:05 AM. Reason: left some info out
listen to mfic ^^^^^he knows what he is talking about. there is always more than one way to skin a cat, but some people are so used to doing one way, they refuse to learn a new way, even if it is better, they had to hack tunes and pull all kinds of tricks out befor they had the capabilitly to do it other wise, but now you have options.......y not do it right? Disadvantages of using MAF in boosted applications
* Your fueling will be completely wrong under many conditions because once you max the maf table the computer looks to the other fueling tables & pretty much is just guessing at that point. Fueling isnt always just rpm dependant so when you've only got 1 wot fueling table(power enrichement) which is done by rpm only your basically guessing at what # to put in. This also limits you in the fact that you can't have variable boost levels...once the maf maxes it maxes but you've only got one pe table thats only rpm dependant rather then boost dependant so if your commanding 11.5:1 at 5500 rpms on 5psi its still going to command 11.5:1 at 5500 on 10psi yet your flowing a ton more air at that point meaning your going to go leaner at 10psi more than likely.
* Unless you opt for the MAF RTT custom 1 bar OS you probably don't have access to Real Time Tuning and if you did consider the 1 bar maf OS your only now 1 credit from the 2 bar custom SD OS and doing it the right way.
* No way to change boost levels without reflashing in a different tune
Take your pick.
Your statement makes sence if you are running a stock maf table . The LPE maf comes with a wider rage table to alow for a lot more air . I am not sure the TSP one does.
Also my car wount let me use RTT and dosent seem to want to alow me to SD tune and the maf seems a lot easier to me .
IMO you dont really need a low octane table if it gets knock it will pull timing thats it . Mustang tuning software only alows maf tunnig they do it the same way and they don't ween to have problems making big power on sc cars .
Also my car wount let me use RTT and dosent seem to want to alow me to SD tune and the maf seems a lot easier to me .
IMO you dont really need a low octane table if it gets knock it will pull timing thats it . Mustang tuning software only alows maf tunnig they do it the same way and they don't ween to have problems making big power on sc cars .
Stock MAF table... so then, how do propose getting around the fact, without blind halfing/fractioning tables (as eluded to elsewhere in this thread), the PCM's internal MAF airflow limit is 512g/sec? Sure you can change any number BENEATH that, but that's all that is supported and no aftermarket MAF will change this for a 98-02 f-body. Here's another point.... mustang engine management and GM engine management aren't written the same way and don't work the same way, does that help you out?
I feel like I have typed this description a lot lately...
He didn't say "tune your car to 5 and then run 10".... If you are running 10psi, your MAF is almost absolutely maxxed out, never seen one that wasn't at that level. Nobody said the freq won't go up, but the PCM stops caring about it at 12ish Khz regardless of how much higher it goes.
WHat I was saying is if you want to run 10#'s at the track an 5# ont the street if you tune for 10 #and run 5 there should be no need to re flash the tune .
Not sure why your getting so mad but . There are ways around it I was told form a very repertable tuner Grag banish that one, the LPE MAF will read higher then that and 2 that you can shrink the base car in the tune like instead of a 5.7 make it think its a 3.6 (not exact #'s) and it will also extent the maf table . But what whould he know he only writes entire calabrations for major car makers .
Stock MAF table... so then, how do propose getting around the fact, without blind halfing/fractioning tables (as eluded to elsewhere in this thread), the PCM's internal MAF airflow limit is 512g/sec? Sure you can change any number BENEATH that, but that's all that is supported and no aftermarket MAF will change this for a 98-02 f-body. Here's another point.... mustang engine management and GM engine management aren't written the same way and don't work the same way, does that help you out?
I am going to give it a shot on my car and if it doesent work Ill SD tune but till then I thats how I will do it . I dont forsee any problems with the maf
Last edited by CamaroSS19; Mar 11, 2008 at 01:28 PM.



