PROM BURNING? or DFI?
08-22-2001, 10:46 PM
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PROM BURNING? or DFI?
I am have few questions and I was hoping someone could help me out. I am currently running a 406 SB, in my 88 IROC-Z. I have the stock computer with a TPIS PROM and the car runs real fast. I have broken 2 stock rear ends already so I know it has a good amount of power. About 2 weeks ago I believe my stock computer went bad. It won't run for **** and it gives tons of codes for stuff that isn't wrong. With my computer misfortune I see this as the perfect time to upgrade my setup. My car is MAF (mass air), and I have performed all the MAF modifications but I know it is still and restriction on the big stroker motor, and I also believe the stock air cleaner assembly (y shaped thing) is also a big time restriction. Here is the problem. I really don't know what to do. Should I invest some money into a DFI system, I know this would get rid of the MAF sensor and make my car speed density MAP. If yes what is the best system to run, so far I have looked at speedpro(SEFI8LO), Accel old & new Gen VII, Haltech. Now I have tons of options there, would I be better off with batch fire, or sequential, and is the closed loop wide band O2's worth the money. OR should I get a stock MAP GM computer, buy a MAP sensor and convert my harness over to make it a MAP harness and invest a little money into the EPROM burning software and make my own speed density chips. I also would like to let you know that I plan on adding a vortech or ATI supercharger this winter. Will a stock GM computer with programming run with a supercharger making 12-15 psi of boost. Some people say yes some say no. I have had alot of people tell me the stock GM computers are top notch if they have the right chips & calibrations. I have seen a few 10 second buick GN's running stock computers with owner burned chips. If anyone can shed some light or experience on this subject it would help me alot
Thanks
Jason
jnjspdshop@aol.com
Thanks
Jason
jnjspdshop@aol.com
08-23-2001, 06:51 AM
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Car: '84 Fiero ('01 GA interior)
Engine: '96 4.0 Aurora
Transmission: '96 4T80E
This is a hard question to answer. There are pros and cons to all systems. The stock system is a great system that, once learned, can do amazing things. It is also very cost effective and rugged. You might want to find out why the original took a dump on you before plugging something else in. If you have the time and patients to do it, the stock system is for you. There are others here far more tech savy than me, that know the ins and outs of the different systems, but if you have DFI questions, don't be afraid to ask.
08-23-2001, 10:27 AM
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Even though you have posted a similar question on the DIY PROM Board, I will answer it here as you are most likely to get DFI Users to respond here. So by responding here, you are most likely to get a "balanced answer".
As RCR stated, they both have their advantages and disadvantages. It is up to you to determine what is important and unimportant to you.
The biggest disadvantage of the stock ECM that I can see is in very high HP applications. The limitation is primarily the high impedence injectors used on the stock system has limits on the size of injectors you can use. Most DFI systems can support low impedence injectors which are capable of much higher flows. For an all out race application where you want max HP; I would go with DFI.
Most of the DFI systems have their own editor and diagnostic program so you don't have to buy a scan tool. Also, many support "on the fly" changes. This can be an advantage and a disadvantage. In doing my "prom burning", I prefer LOTS OF DATA before making any changes. The more data, the easier it is to determine your overall mixture for Closed Loop operation. I find I often will get some "short term" erroneous information that IF I made a change based on these "short term" values, would result in incorrect modifications. But, I also can see an advantage to "pulling or adding" a little spark to find my "optimum" spark advance.
With the use of Flash Proms, the "wait time" for the erasing of the Flash Prom is eliminated, so this disadvantage of the stock ECM is eliminated on the 7730 SD or 165 MAF ECMs.
The majority of DFI systems use MAP sensors and are similar (in concept) to the SD 7730 ECM. The same "tuning issues" with DFI exist with SD. But, these tuning issues are over played IMO, and I personally find SD easier to tune once you understand the concept of the "VE Tables".
Some of the DFI systems support Wide Band O2 sensors, which is a nice advantage for WOT tuning. But, as Grumpy would say, there are other methods (like reading spark plugs) that make this "weakness" minor. In fact, no matter WHAT YOU DO, you should always look at other collaborating signs, like spark plugs, to confirm your tuning efforts.
The biggest disadvantage of DFI as I see it, is cost. The equipment to burn your own eprom is much cheaper and many of the items (such as a scan tool and BIN Editor) are available for free. But, if you had to buy Diacom (Scan tool) $500 for the Plus Version, an Editor like Tuner Cat ($70) and the Programmer/Burner (Pocket Programmer $149); you are probably looking at just over $700. Most of these items can be available for free or very low cost. If you wanted to go the "freeware" route, you could get into burning your own eprom for under $150. Also, most of the programs etc to burn your own do not need a sophisticated computer and a cheap notebook based on DOS or W95 will suffice. I see these at "Used Computer Stores" for under $100 all the time and I picked up a spare notebook for my "scanning and burning" for $25.00 from a local Newspaper.
Excluding the HIGH HP limitation, there are many advantages of burning your own eprom. With the advent of many of the Editors today, burning your own eprom has become a much more viable alternative than it was before. You have access to almost every constant and table within the SD 7730 ECM now and the stock ECM has features that many of the DFI systems do not. You have GM's Highway Mode to assist in getting excellent gas mileage. I get almost 30 US MPGs on highway driving. The stock ECM is fully emissions compliant, plus you have control over the fans, EGR, Purge Canister, TCC Lockup, Air Divertor which many of the DFI systems do not, as they are not necessarily designed for "emissions". Just double check to make sure.
The single BIGGEST advantage I can see to the stock ECM is you can modify the actual Assembly Language by creating a "disassembly" of the BIN. It is not all that difficult and far easier than most think. There are "hacs" available to assist in documenting the "disassembled" code and create fully documented Source Code. You don't like the way the stock GM code handles a particular situation? Or, you would like to add some new routine (I am currently looking at modifying the way the stock GM ECM handles the TCC at WOT); you can do it with the source code.
Modifying the Source Code is a new area and not too much information is available on this aspect of modifying the stock ECM as most of the guys that have done this are not willing to share the information they know about this. While the DIY PROM Board is NOT able to give Source Code out, we are more than willing to teach you how to create it and where to get a hac to help you document it.
If you don't know the Motorola HC11 Assembly Language, then documenting the "disassebly" is great way to teach yourself the HC11 Assembly Language. Again, it is not that hard.
As RCR stated, they both have their advantages and disadvantages. It is up to you to determine what is important and unimportant to you.
The biggest disadvantage of the stock ECM that I can see is in very high HP applications. The limitation is primarily the high impedence injectors used on the stock system has limits on the size of injectors you can use. Most DFI systems can support low impedence injectors which are capable of much higher flows. For an all out race application where you want max HP; I would go with DFI.
Most of the DFI systems have their own editor and diagnostic program so you don't have to buy a scan tool. Also, many support "on the fly" changes. This can be an advantage and a disadvantage. In doing my "prom burning", I prefer LOTS OF DATA before making any changes. The more data, the easier it is to determine your overall mixture for Closed Loop operation. I find I often will get some "short term" erroneous information that IF I made a change based on these "short term" values, would result in incorrect modifications. But, I also can see an advantage to "pulling or adding" a little spark to find my "optimum" spark advance.
With the use of Flash Proms, the "wait time" for the erasing of the Flash Prom is eliminated, so this disadvantage of the stock ECM is eliminated on the 7730 SD or 165 MAF ECMs.
The majority of DFI systems use MAP sensors and are similar (in concept) to the SD 7730 ECM. The same "tuning issues" with DFI exist with SD. But, these tuning issues are over played IMO, and I personally find SD easier to tune once you understand the concept of the "VE Tables".
Some of the DFI systems support Wide Band O2 sensors, which is a nice advantage for WOT tuning. But, as Grumpy would say, there are other methods (like reading spark plugs) that make this "weakness" minor. In fact, no matter WHAT YOU DO, you should always look at other collaborating signs, like spark plugs, to confirm your tuning efforts.
The biggest disadvantage of DFI as I see it, is cost. The equipment to burn your own eprom is much cheaper and many of the items (such as a scan tool and BIN Editor) are available for free. But, if you had to buy Diacom (Scan tool) $500 for the Plus Version, an Editor like Tuner Cat ($70) and the Programmer/Burner (Pocket Programmer $149); you are probably looking at just over $700. Most of these items can be available for free or very low cost. If you wanted to go the "freeware" route, you could get into burning your own eprom for under $150. Also, most of the programs etc to burn your own do not need a sophisticated computer and a cheap notebook based on DOS or W95 will suffice. I see these at "Used Computer Stores" for under $100 all the time and I picked up a spare notebook for my "scanning and burning" for $25.00 from a local Newspaper.
Excluding the HIGH HP limitation, there are many advantages of burning your own eprom. With the advent of many of the Editors today, burning your own eprom has become a much more viable alternative than it was before. You have access to almost every constant and table within the SD 7730 ECM now and the stock ECM has features that many of the DFI systems do not. You have GM's Highway Mode to assist in getting excellent gas mileage. I get almost 30 US MPGs on highway driving. The stock ECM is fully emissions compliant, plus you have control over the fans, EGR, Purge Canister, TCC Lockup, Air Divertor which many of the DFI systems do not, as they are not necessarily designed for "emissions". Just double check to make sure.
The single BIGGEST advantage I can see to the stock ECM is you can modify the actual Assembly Language by creating a "disassembly" of the BIN. It is not all that difficult and far easier than most think. There are "hacs" available to assist in documenting the "disassembled" code and create fully documented Source Code. You don't like the way the stock GM code handles a particular situation? Or, you would like to add some new routine (I am currently looking at modifying the way the stock GM ECM handles the TCC at WOT); you can do it with the source code.
Modifying the Source Code is a new area and not too much information is available on this aspect of modifying the stock ECM as most of the guys that have done this are not willing to share the information they know about this. While the DIY PROM Board is NOT able to give Source Code out, we are more than willing to teach you how to create it and where to get a hac to help you document it.
If you don't know the Motorola HC11 Assembly Language, then documenting the "disassebly" is great way to teach yourself the HC11 Assembly Language. Again, it is not that hard.
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