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  • MAP sensor instead of MAF?

    Has anyone every looked at using a MAP sensor on our engines instead of a MAF sensor when upgrading to FI?
    -Mike
    If you are wondering where the avatar came from look here... Link
    98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
    85 Camaro - 1969 350ci, 503BHP

    Owner - RIES PEFORMANCE

  • #2
    i'm not sure that its possible w/the stock ecu. if you run something like megasquirt its very easy,esp since we already have a seperate iat sensor.
    buy me,95 conotur se
    http://contour.org/ceg-vb/showthread.php?t=36638

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    • #3
      What do we know about the Contique ECM's? Has any body ever studied the pin outs and what kind of software logic is being used and if it can be modified. I know the Honda guys have had pretty good success with this aspect of things.

      I guess I don't know the limitations of the SCT Xcal PRP either... If a guy were to look at the pin outs of the ECM and determine that there was an unused pin and a unused sensor power pin... I wonder if you could wire s MAP sensor in that way and then set it up to be monitored via the Xcal programming and use it as an input to determine your AFR.
      -Mike
      If you are wondering where the avatar came from look here... Link
      98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
      85 Camaro - 1969 350ci, 503BHP

      Owner - RIES PEFORMANCE

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      • #4
        you can find the pinouts on the old forum.
        buy me,95 conotur se
        http://contour.org/ceg-vb/showthread.php?t=36638

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        • #5
          Do you mean switching to a speed density system as opposed to MAF? There's TONS of info on MAF vs SD in the mustang world...how you can translate it to the CSVT, I'm not sure, but it's a goo dplace to start looking IMHO.

          Good Luck!

          RJ


          '89 lt Titanium
          Round wheels
          Black tires
          Runs on gas
          One steering wheel

          BRAPPLESAUCE

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          • #6
            Originally posted by tozovr View Post
            Do you mean switching to a speed density system as opposed to MAF? There's TONS of info on MAF vs SD in the mustang world...how you can translate it to the CSVT, I'm not sure, but it's a goo dplace to start looking IMHO.

            Good Luck!

            RJ
            Yea that's what I'm trying to do. Speed density likes boost more then MAF systems. Is there a particular Mustang site that you can point me to?
            -Mike
            If you are wondering where the avatar came from look here... Link
            98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
            85 Camaro - 1969 350ci, 503BHP

            Owner - RIES PEFORMANCE

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            • #7
              What issues are you having? Speed density has more issues adapting to FI than than MAF systems.

              Here's an article on someone switching to a MAF setup because of issues with speed density: http://www.fordmuscle.com/archives/2...sion/index.php

              All the newer cars are MAF and the FI setups work fine as long as you tune the car correctly.
              Visit: 3LDuratec.com for a prepped 3L ready to drop in!

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              • #8
                Originally posted by Blackcoog View Post
                What issues are you having? Speed density has more issues adapting to FI than than MAF systems.

                Here's an article on someone switching to a MAF setup because of issues with speed density: http://www.fordmuscle.com/archives/2...sion/index.php

                All the newer cars are MAF and the FI setups work fine as long as you tune the car correctly.
                Yea that's what I've been finding. I've just heard that MAP sensors are better for FI, but apparently that's not necessarily true according to what I'm finding in my web searches...
                -Mike
                If you are wondering where the avatar came from look here... Link
                98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
                85 Camaro - 1969 350ci, 503BHP

                Owner - RIES PEFORMANCE

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                • #9
                  in the early 90's gm had maf sensors on 2.8 v6's. but they were cheap and unreliable. they had a bulletin out to switch to the speed density system since they had a map in place already the computer just relied more on that information and eliminated the maf reading. performance went down as well as fuel efficiency as a result. i was told then by a gm engineer that there is no substitute for the maf reading. he said it was a shame their maf's were so cheaply made! lol i don't know if that helps but it's interesting.
                  95 Mystique Zetec ATX
                  95 Ford Contour ATX

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                  • #10
                    Speed Density is usually easier to calibrate for high HP combinations than Mass Air, but only because it is far more difficult to build and calibrate a MAF sensor that can for example precisely meter 0-1000 cfm (which would be necessary at or over 1000 hp) while outputting a 0-5v signal which must then have a corresponding calibration factor in the ECM. Speed density on the other hand merely needs a MAP sensor capable of reading the relavant pressure (multiple bar is not uncommon) and an ECM lookup table that has been scaled to include relevant operational pressure ranges.

                    However, hardware capabilities aside (lets assume that we have capable hardware for our engine output goals) MassAir tuning is easier than SpeedDensity. For MassAir you input the MAF calibration info into the ECM, establish a series of AF ratios required for a variety of Load:RPM bins and the ECM is able to determine fueling requirements based on readings from the MAF, assuming settings are accurate fueling should be accurate. On the other hand, with Speed Density, the AF goals based on Load:RPM still need to be established, but one must establish a Volumetric Efficiency table (VE) for an individual engine or fudge it enough to work generically (OEM style). Furthermore, the SpeedDensity system will only accurately compute fueling needs when the VE table is properly established for the engine which means running it though all the operational areas (on a dyno preferably) and manually adjusting the VE table.

                    Either way, closed loop operation (especially with WB) simplifies matters slightly in that the ECM is able to compensate for diminished precision as components age, for estimations made during mass production, or compromises made during tuning. Self adapting (learning) systems aid in keeping everything happy as well, but either/both of these adaption methods are tuning assistants and not replacements for precision tuning.


                    Speed Density systems can be every bit as fuel efficient as Mass Air, but only when the lookup tables (VE specifically) are tuned to accurately reflect the demands of the engine being controlled and are adjusted over time to reflect changes in engine demands with age.

                    The biggest hurdle that must be overcome with the majority of Mass Air systems is that the end user is retuning a factory ECM to provide fueling control during conditions never anticipated by the original programming. This results in caps on how far a factory ECM can be manipulated to continue providing fueling. Factory ECM's tend to have hardware and/or firmware limits on how advanced and how precise they can function; at some performance point you reach a limit on how far you can push a factory ECM.

                    All that being said, most (if not all) Mass Air systems resort to open loop direct fuel look up bins at high load (WOT operation) which can often be scaled to cover extreme operation areas otherwise beyond the ECM's capabilities by dyno tuning and manually telling the ECM how much fuel to spray.
                    Last edited by Pope; 02-13-2008, 02:00 PM.
                    99 Contour SVT

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                    • #11
                      one word:
                      MEGASQUIRT!!!!!!!!!
                      buy me,95 conotur se
                      http://contour.org/ceg-vb/showthread.php?t=36638

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                      • #12
                        If i was getting a standalone i would go Autronic.
                        99 TRed Contour SVT # 1853 out of 2760 - SOLD
                        230.2 WHP @ 6500
                        237.0 WTR @ 2250
                        99 Tropic Green SVT
                        96 Mystic Cobra: Procharged and Intercooled. Needs a new BOV

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                        • #13
                          Originally posted by 95pgt-t View Post
                          one word:
                          MEGASQUIRT!!!!!!!!!
                          it runs my Mustang.
                          99 Contour SVT

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                          • #14
                            Pope thanks for the input and comments. You see very knowledgeable with this... did you pick all of this up from tuning your Stang?

                            VE tables are extremely difficult (I think) to construct. Having to create that table alone is enough to steer me away from attempting to switch to a MAP system.
                            -Mike
                            If you are wondering where the avatar came from look here... Link
                            98 SVT Contour - HoK TruBlue|CF roof|#49/6535 DOB 3/25/97|550whp here I come|Follow my extremely slow 3L/turbo build here Link
                            85 Camaro - 1969 350ci, 503BHP

                            Owner - RIES PEFORMANCE

                            Comment


                            • #15
                              Originally posted by CSVT#49 View Post
                              Pope thanks for the input and comments. You see very knowledgeable with this... did you pick all of this up from tuning your Stang?

                              VE tables are extremely difficult (I think) to construct. Having to create that table alone is enough to steer me away from attempting to switch to a MAP system.
                              somewhat.

                              I started learning by researching the various options for my Mustang as I constructed it. The DIY and Open-Source nature of the Megasquirt system coupled with the various code variants that make it capable of handling most of the features available in other standalone systems, but for half to quarter the cost. I am no expert and there is much that I have not yet committed to memory, but I like to think that I have the general concepts down.

                              Even if you do not use a Megasquirt system, the MegaManual (http://www.megamanual.com/) is a wonderful resource for reading and developing an understanding of how ECM's function. Some of the material is obviously specific to the MS unit (primarily settings and tuning specifics), but the concepts in play can be generalized to probably all fuel injection systems.

                              Additional resources that I have found of value are tech books issued by various manufacturers for the instruction of their employees or for use in trade schools to train new techs/mechanics. These can be found in a number of ways: eBay, Amazon, trade schools that may have old versions to unload (check and the end of each school year), and from techs/mechanics that may have old editions lying around. I have read the Ford, GM, and one of the import's (Honda I think) instruction manuals from a couple years ago, for the most part these resources are light on the background of how and why the systems are implemented the way they are, and heavy on diagnostic procedures, but understanding how to diagnose failures and the effects that component failures have on the ECM will aid in understanding the system functions.

                              Automotive Computer Controlled Systems: Diagnostic tools and techniques by Allan W. M. Bonnick is another decent reference that approaches the ECM from a generic perspective explaining how various systems function, the physical manner in which sensors and controls operate and how to determine if there are problems in the components.

                              Understanding Automotive Electronics by William B. Ribbers, on the other hand, is a more technical reference book with more emphasis on the hows, whys, and mathematics behind the control functions.

                              Although slightly outdated, and having nothing directly to do with the ECM functions, I must recommend that anyone looking at Forced Induction (most specifically turbos) read Maximum Boost by Corky Bell. Despite being written for the purpose of understanding turbo systems, a centrifugal supercharger is effectively a turbo compressor being driven by a belt, so much of the compressor tech is applicable, the book also covers intercooling which is obviously applicable, intake design, fuel system alterations (FI and Carb), and how increased pressure impacts the engine, so it is all good information to take in.

                              I could go on and on, but I will stop here, as this should give an idea of the types of resources available. The information is widely available and not hard to find. I leave the topic of references with two parting thoughts: For what it is worth, one can find various levels of ECM tech on Wikipedia depending on the topic, which makes is a good entry level information source, and that the MegaSquirt community is a great resource for learning the how and why ECM's function as they do; as previously detailed the MegaManual (http://www.megamanual.com/) is a great place to gain an idea of why computer controls work as they do, but if you really want to understand how controls function, buried in the discussions at the http://www.msefi.com/ (the MS Forum) if one should care to look, one will find development information that goes so far as to discuss the algorithms used to drive system functions and what industry papers the functions are derived from (serious engineering material), additionally, if inclined, the C++ source code the for entire MegaSquirt system is freely available so that could be reviewed to understand how it functions.


                              In my opinion VE tables are not difficult, time consuming, but not difficult. However, I have to venture a guess that the factory ECM is not going to support speed density over mass air since the control algorithms would be wrong. If you did decide to move toward a stand-alone, the tuning softwares that accompany the units will usually generate base tables from the input of a variety of factors and estimations. Fine tuning is then performed to refine the tables to the engine, most easily performed on a dyno where operating conditions remain controllable and adjustable to suit the section of the table under refinement. I do not know off hand what stand-alone ECM's support MAF sensors and which ones MAP, but the Megasquirt can use either or both according to user defined settings.
                              99 Contour SVT

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