hmmm????
when should you really sit down and say," alright I think Im making at least X hp and this maf system cannot accurately support any more."

 

I am currently building a 406 mini ram engine that should make between 500-550 hp. TPIS told me that a MAS flow system would be able to support this combination and I would not have to switch over to a speed density system unless I wanted more then 550 HP.

Hope this helps.

------------------
1988 Formula 5L/5sp 3.45 gears, SLP cold air kit, MAS gutted, TPIS air foil, TPIS AFPR, MAC headers, Mac under drive pulleys, MAC cat back, Relocated MAT.
Best ET street tires 13.85
Best 60 FT street tires 1.930
Best MPH street tires 99.29

 

yea thats the kind of thing I wanted to know.
did they give a reason for the value of 550 they quoted you??

 

Are u talking about a limit with the stock chip the MAF cars have or the actual MAF??

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Looking For:

87 IROC-Z 350 TPI
84 TRANS AM 305 H.O.

[This message has been edited by IROCZTWENTYGR8 (edited March 16, 2001).]

 

The MAF has two restrictions. First, it's a bottleneck in the intake. Removing the screens gets over 700cfm of flow supposedly, but those screens straighten the flow over the hot wire. Second, the MAF computers only read to 255 grams/sec. So after 400 or 500 cfm (I calculated it once and forgot the number), the computer can no longer measure airflow. That doesn't mean it can't make power over that mark, it just doesn't know how much air is coming in.

 

right thats what I wanted to know.
so the actual MAF cannot measure over a certain amount of air. do you know what HP level that corresponds to?
seems like 500 cfm is a pretty low number for the upper limit on the operational range of an maf unit.
is there any way to plop another bigger unit in there and reprog. the chip to recognize the larger range on the new MAF???

this question started as just a curiosity, but now I am thinking about building a 377 destroker under some form of TPI (wether it be the LTR or mini or super ram). personaly I would like to see if someones previous Idea of detuning the base and runners of the LTR setup would work.
by this I mean getting a set of SLP runners and siamesing the ENTIRE length along with a certain amount of the base to get a more favorable runner length and also increase plenum volume. both of these would lend themselves greatly to A high RPM motor BUT--
I dont know how I could get the MAF system I have to handle all the extra g/sec that this system would pull in.

 

Since you are already spending a bunch of cash to retain the FI, spend a few bucks more and swap it to speed density if youre worried about it.
Its hard to put a HP number on a CFM rating and be accurate. Theres a 502 GM built running a stock TPI size throttle body. Ive seen more than a few dyno tests showing actual CFM's much less than predicted. I'd say if you descreen the MAF and are running around what TPIS says, you should be just fine. IMO descreening the MAF isnt a problem unless you are careless and damage the MAF in the process. Ive never had any driveability problems after doing it, so I wonder if the people that do have problems are doing something wrong.

I think the number is like 440 something CFM at the max reading of the MAF. Using a bigger MAF wont fix this problem, its a problem in the way the code in the chip is written and so far nobody I know of has found a way around it. The buick turbo guys have the same problem, but take a look how fast those guys are running on the stock maf/ecm. Its a problem for sure, but not something that cant be dealt with. At this time it would take a fair amount of effort and research to deal with though.

 

It's hard to predict hp by cfm, look at NASCAR. I don't think anyone has come up with a fix for our style MAFs yet. GNs can switch to a bigger MAF with a "translator". There should also be a way to make the ECM code read higher than 255. But, it takes people smarter than me to figure out how to do it.

As for switching, don't worry about it unless you are gong to make some big numbers or you are looking for the perfect tune to buy you .05 sec at the track. I'm looking at around 400 hp and I would switch, but the switch has a lot more pitfalls in a Vette. For a thirdgen, it's a much more bug free swap. Check this out for more info - http://www.eecis.udel.edu/~davis/z28/ecm_swap_730/

 

I dont really care so much about the gross cfm rating of the MAF sensor but what I do want to know is...

if you swap in a bigger (larger diameter) MAF, wouldent that lend itself to lower velocity and therefore less current required to maintain MAF voltage. then the computer would be reading within the 0-255 range but you would have to tell the computer (by new values in the chip) that 0-255 covers a whole lot more ground than it used to.

in this way couldent you use MAF for any level of airflow?
or is there some problem with getting the computer to recognize a new algorithm for MAF voltage to g/sec???

I may be wrong that this is how the computer reads the MAF, butit seems to me that you can always (within reason) increase the diameter of the tube you put the hot wire in and thereby increase the MAFs practical range????????

 

I believe your correct..... The MAF tables would have to reflect greater changes in the fuel and spark tables..... the limiting factor in the 255 is the 8 bit procssor in the ECM.

------------------
Hank
87'IROC Z28
Hanks 87 IROC

 

Hank, I've been diving into the code in the eprom and 255 is only a limitation if the value is defined in a single constant field. If the field is defined as a "double byte" you actually have 65,535 possibilities.

So, theoretically, it strikes me that if you got a MAF that could register higher than 255; adjusted the readings to the corresponding voltage (ie double the value if using a 512 gm/sec MAF) and then redefined the MAF tables using "double byte" constants instead of "single byte constants"; then you could make the MAF eprom register higher than 255 gm/sec.

This is in fact what I am contemplating doing with the SD eprom for the 2 Bar MAP. The MAP basically reads 2 Bars by registering the voltage half of a 1 BAR MAP. Thus I just modify the Assembly Language to double the SD's MAP value and change all the VE tables to be double byte and extend the table range.

With the SD eprom, this is easy as only 58% of the eprom is used, leaving 42% free for more data and instrutions. The problem with the MAF eprom is that it is very tight and has very little free room. So while it is theoretically possible, from a programming point of view. Lack of "available space" on the MAF eprom may make this impossible.

I need to talk to someone with a MAF system that has reversed engineered the source code and is familiar with Assembly Language Programming to confirm if enough room exists to even consider this option.

 

I should add that the reason the SD eprom has so much available room is because it is a 32K chip where as the MAF eprom is a 16K chip.

 

Glenn,
can't you just put the MAF ECM program into a 32K chip, or will these 2 be incompatible?

 

well I may be wrong but,

I dont think you need to have all the extra data points for this theoretical MAF we are discussing.
if we simply use the existing 255 points, and change the algorithm to reflect a greater range.
what I mean is that lets say the old tables have the formula

MAF voltage x 100 = g/sec of airflow in the tables. ( since I dont know the actual formula I will use this one for example)

this way the ECM sees a range of 0 - 5.00 volts divided up into 255 descrete points (airflow ratings) where each point represents a descrete airflow in the table.

now if we CHANGE the MAF to one with a larger diameter, by the law of continuity
the velocity in the larger tube should be lower.
the 255 point table would still be useful but only if we change the algorithm for the ECU to see that the scale is different.

so the new formula would be something like

MAF voltage x 150 = g/sec

this way there would still be only 255 points of possible data in the tables they would just cover a higher range and be less sensitive to smaller changes.

I think this topic may be leaning twoards the PROM board but as long as people respond I am happy.

 

F22, of course you can put the MAF program on a 32K chip, but the ecm will still only access 16K of memory on the eprom. Solves nothing.

88, the problem is, the stock MAF won't register higher than voltage than 5 volts for 255 gm/sec. Having you MAF max out at 3,000 rpm means that after 3,000 rpm you have no correction values. You need a MAF that will register 512 gm/sec at 5.0 volts (and an ecm/eprom capable of interpreting these values). The problem is you need to modify the eprom code to handle this interpretation, plus you need to increase the "precision" of the MAF Scalar tables.

But first, you must get a MAF that will register 512 gm/sec @ 5.volts.

 

glenn I think that is what I just said although i could be wrong.
using the same 0-5 volt range you COULD increase the g/sec range by increasing the diameter of the tube. this would have to be used with recalibrated tables in the eprom but I think It would work.
I dont think that losing a small amount sensitivity would really matter that much.

 

No, the stock MAF still only can register a maximum voltage, which corresponds to 255 gm/sec. More voltage than what the ecm expects, triggers and error.

255 gm/sec is the "speed limit" at max volts. Its like trying to break the speed of light...not possible.

You need a MAF capable of registering 512 gm/sec at max volts(effectively halfing the voltage of a corresponding 255 gm/sec MAF). Then you must alter the eprom itself to double itself by converting all the data fields to "double constant" bytes so they can compute > 255. But, the eprom is almost totally full, so you really have no room to make alterations. Bottom line, your hooped. 165 MAF is stuck with 255 gm/sec. If I ever figure out a way around this I will let everyone know, because I will become rich.

 

you are not reading what I am writing.

the MAF is only capable of 255 g/sec because the velocity at that rate is high enough to demand the full 5 volts from the hot wire to maintain temp.

if you increase the diameter of the MAF housing it LOWERS the velocity for a given flowrate. now for the same voltage in the hotwire (velocity) there will be a greater flowrate. all that is left to be done is to program the eprom to a new scale.

your objection is correct but you must understand that by increasing the diameter of the housing you are reducing the velocity for a given flowrate.

 

Guys, isn't the limit a hrdware thing in the ECM? The MAF only throws out a voltage, it does not do the conversion to gm/sec, the computer does.

------------------
"Pray to God, but at the same time use your hands"

-Greek Proverb

 

I re read my post and it sounded a little hot.

sorry, dont mean to be a jerk.

the solution you are suggesting involves changing the MAF to a new hot wire that reads for higher V's than 5.???

all you would have to do for my soln is to take the old hot wire and venturi and electronics out of the old 165 and make a larger dia. housing.

then you could use the same sensor and stuff but just program the tables in the eprom to descritize the larger range of the MAF.

 

Max,

Believe me, the Red Devil and I know how much time is involved. The results are promising, however. There may soon be a ThirdGen running around with a stock MAF and mostly stock ECM that can actually [b]meter[b] air over 500 g/S and calculate fuel correctly. There are just a few other nuisance problems to deal with, but it's closeer than I've ever seen anyone else come before.

Don't worry, when it's ready, you'll know.

------------------
Later,
Vader
------------------
"I'm'a do Things My Way - It's My way or the Highway."
Adobe Acrobat Reader

 

Oh I figured there was. I know RD is on the case, and I was pretty sure you were throwing your .02 in ... or maybe its .98 and his is .02
I looked at the code, and it looks doable, but I dont know the language they are using very much and my brain is still a bit fried from last semester at school. Im not sure I can add 1 and 1 right just yet. Hell Ive been looking at the 89 stuff for 3 days now and its still in Greek

This voltage thing has me thinkin though, isnt the voltage near max when the airflow is around 255, meaning the maf itself is becoming a problem as well unless you recalibrate the maf or change the voltage? If I'm off in lala land, no real surprise right now...

 

Actually it's more like his .99 and my .01! To say this guy is sharp would be an understatement. I just come up with the questions.

 

If the MAF is such a limitation then how do these Buick guys running low 11s still manage to use stock ones...and if they can do it why can't we?



------------------
87 IROC-Z, 5.7, auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, SLP .218/.224 .495/.502 cam, Comp 1.5 roller tip rockers, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax\Flowmaster catback. Coming Soon(?)- Fasttrack/Accell DFI

1989 Pontiac 20th Anniversary Turbo Trans Am - 161,000 miles, !cat, 9" K&N

 

They use, IIRC, a digital MAF stock, and this allows them to use, with the help of a 'black box' and/or translator to use the later, newer MAFs and read to 512 gm/sec.

------------------
"HEY laser lips... Your mamma was a snowblower!"

-#5

 

ok this topic seems to have heated up quite a bit tonight but I was wondering why you wouldent just use my solution to the MAF limit problem.

Vader, are you saying that you and RD are working on a way to get the computer to recognize a larger voltage range from the MAF.
I dont think you meant that seeing as how you said It was a "stock" MAF meter.
so how would you get readings for airflow greater than the max voltage that the MAF can convey?? isnt the stock circut loop for the MAF saturated at 5V??

also, if there is another topic going that is related to this one on the prom board let me know because I would like to read more on what signal the MAF actually produces and what the ECM does with it.

thnx

 

From what the TPIS book says, it may only measure up to 255 g/sec airflow, but if your intake exceeds this, the mapping can be 'fudged' to support it. You only really need to register the airflow at light throttle to improve gas milage. When the foots to the floor its open loop anyway and relies on the PROM/fuel pressure to get things stirred up.

 

My boss's 87 Calaway Twin Turbo w/ 345 hp and 450 ft-lbs of torque still uses a MAF.

James

 

Originally posted by 88305tpiT/A:
if we simply use the existing 255 points, and change the algorithm to reflect a greater range.
what I mean is that lets say the old tables have the formula

MAF voltage x 100 = g/sec of airflow in the tables. ( since I dont know the actual formula I will use this one for example)

Since 5 volts corresponds to 255 g/sec the scalar value is probably somewhere around 255/5 or 51.

this way the ECM sees a range of 0 - 5.00 volts divided up into 255 descrete points (airflow ratings) where each point represents a descrete airflow in the table.

OK. First, there are not 255 discrete points that the MAF reads at. If you look at the MAF tables there are actually only 54 I believe, but your theory thus far is correct.

now if we CHANGE the MAF to one with a larger diameter, by the law of continuity
the velocity in the larger tube should be lower.
the 255 point table would still be useful but only if we change the algorithm for the ECU to see that the scale is different.

so the new formula would be something like

MAF voltage x 150 = g/sec

this way there would still be only 255 points of possible data in the tables they would just cover a higher range and be less sensitive to smaller changes.


It is on this end where the problem lies. Your theory would work, but if the scalar multiplier was changed to say 60 (compared to 51), a reading from the MAF of 5 volts would then correspond to 300 g/sec of air. But, the 8 bit processor cannot take in a number greater than 255 g/sec. This is because 255 is the largest number that can be used in 8 bit hex code. If you chane the scalar to anything higher, the ECM can no longer use the data.

I think the thing you were missing is where the 255 becomes the limiting factor. It has nothing to do with the MAF, everything you said would work perfectly, it's just that the ECM cannot handle a number larger than 255 g/sec for calculations.

------------------
Black 88 GTA L98
261 RWHP, 345 RWTQ
13.406 @ 103.72 MPH
ZZ4 bottom end, Edelbrock 6085 heads, LT4 HOT cam, GMPP 1.6 RR's, ported stock TPI, SLP 1 3/4" headers, no cat, Dynomax cat-back, Stock PROM
E.T.F.A Member #11

[This message has been edited by Scott 88 GTA (edited March 17, 2001).]

 

aaaahhhhhhhhhhhhaaaaaaaaaa!!!!

yes thank you for clarifying.
(not being sarcastic -- that was a great explination)

but I still think that using the 255 points algorithm for the maf signal would be OK if...

you just have to have the tables that use the MAF number recognize that 255 needs more fuel than It used to.

I understand the limitation of the computer dealing with only 8 bits but it still seems that you could use the 8 bit number in the fuel tables, then just readjust the fuel map numbers in the tables.

now this IS alot more work than I though it would be by just adjusting the MAF algorithm.

BUT it still seems doable provided you change the fuel/MAF tables, and of course modify the MAF as I have said before.


Let me give you insight into my reasoning here..

the GM MAF system uses 8 bits for some values; I gather from what I have read.

now, the guys at GM didnt make it 8 bit because they needed a certain RANGE on the system, they did it because they wanted a minimum SENSITIVITY with the range of the sensors they used with it.

this makes sense when you see that they used the same computer in many different kinds of cars.

now, for the analoge range of the sensors (example being the MAF) being fixed, they must have figured that they needed so many digital levels (256) to properly run the engine (i.e. for good drivability computer must have no less than 256 conditions that it can map fuel to). but if you think about it, this has a huge saftey factor in it. You only need like 50 or so points to properly meter fuel to keep the engine streetable. it might be pretty jerky but it would run fine.

sooo......

why not decrease the sensitivity of the factory's 256 points by INCREASING the RANGE of the sensors.
this is a direct trade off and does NOT require ANY more bits to accomplish. the 255 that the computer uses to signify full output from the MAF would be the same number -- 255 -- its just that the tables would meter more fuel for that specific value.

I guess this would all boil down to recalibrating the fuel curve SLOPE. as the MAF number goes from 0-255, the fuel number would go up FASTER than with a normal MAF. you would still reach 255 as your limit, except now the computer is giving more fuel.

if anyone understands what I am talking about then you have accomplished something. because I have never seen a GM eprom file so my explinations must be horrible.

 

88350TPI,

I think you've missed the big picture here,... the MAF is not the restriction preventing accurate airflow measurement above 255 gm/s. You need to see the MAF tables in the PROM to understand why. In Table 6, Row 8; the MAF outputs 4.71 VDC which the ECM corresponds to 254 gm/s. However in the succeeding 9 rows of that table VDC continues to increase, up to a max. value of 5.12 VDC, while the interpreted airflow remains fixed at 254 gm/s. Thus the ECM's 8-bit architecture, which has a max value of 255, is the limiting factor. Increasing the voltage output from the MAF will not allow the ECM to accept a higher value than 255. But I don't think that 255 gm/s(which corresponds to approx. 506 cfm) is as much of a limitation as it's made out to be. Considering the IROC race Camaro's used a 390 cfm Holley, and supposedly made 420+ hp @ 6500 rpm, I think we need to examine how(and if) a larger MAF would help or deter volumetric efficiency. And consider how much volumetric efficiency improvement we need from the MAF. Considering max VE occurs at the torque peak(which in most TPI motors is well below 4000 rpm) and decreases at higher rpms, any improvement in the MAF's flow efficiency will likely yield very small gains. It also bears repeating that the ECM does not use MAF inputs at WOT(open loop), so any improvements in the code would have to occur before WOT to be usefull to the ECM.

 

you did not read what I wrote.
that is not what I said

 

No comments - strictly just as FYI - A 1983 9:1 sanctioned 390 carbed engine built by Bo Laws dynoed 472 horses at 6500 rpm. With no more than a carb change to a 750 that same engine produced 535 horses at 6500,, and peaked at 549 horses at 7000.

 

88305tpiT/A:

So what you are saying now is that you leave the MAF tables alone, and simply increase the conversion factor to go from g/sec to pulsewidth for the injectors. It's an interesting idea, and should work, but it's kind of "fudging" things a little bit, don't you think?

88IROCs:

255 g/sec actually corresponds to 462.2 CFM,a 350 ci engine is capable of sucking in 506.4 CFM of air at 5000 rpm. A 350 will suck in 462.2 CFM of air at 4563 rpm, so at any rpm after this the MAF doesn't tell the ECM that it's actually taking in more air, and your engine starts running progressively leaner and leaner. This is the major downfall of the MAF system.

 

Thats only if the ecm doesnt see the TPS at WOT. I would say in most cases if you are above 4500rpm, you would be at WOT.

 

Red Devil,

Should I let the cat out of the bag yet? This grams per second "limitation" that everyone is quoting is beginning to drive me goofy - they just haven't seen the obvious yet, and I'm about to bite my tounge in half...

------------------
Later,
Vader
------------------
"I'm'a do Things My Way - It's My way or the Highway."
Adobe Acrobat Reader

 

Scott,

As per our previous discussion; you are correct in the numbers you quoted. 462.2 cfm = 255gm/s and 506 cfm is the amount of air a 350 can draw in at <u> max VE</u>. However, doing a little bit of math, 462.2/506.4 = 0.913. This means the ECM could accurately read VE of 91% on a 350 spinning at 5000 rpm(the MAF can actually measure higher than this, but the ECM would not interpret the VDC correctly). I'd say if you are achieving 91% VE at 5000 rpm on a NA TPI setup you are doing extremely well! And again, getting to 5000 rpm without invoking open-loop would be difficult(and once in open-loop, the MAF output becomes superfluous). One thing I'd like to do(once I put the #1 IROC back together) is to determine at what rpm the ECM senses 255 gm/s - by monitoring the MAF output until it reaches 4.71 VDC. And seeing whether the ECM can be kept in closed-loop up to, and including, that amount of airflow.

[This message has been edited by 88IROCs (edited March 18, 2001).]

 

Ok. I'm new to TPI but here's my views on this discussoin.

1. Seems like the MAF can flow a lot more than the ECM can actually register. The TB is the major flow inhibitor. Here are my reasons:
a. There are many different size TB available. How many different size MAF's are there?
b. Picture the flow going through each. Which will block more? A thin wire or throttle blades and their pivot arm. (picture at partial throttle vice full since MAF is N/A at WOT)

2. The MAF itself is a "dumb" device. It simply tries to maintain a certain temperature on the wire. The ECM registers the voltage being used to maintain that temperature. The MAF itself cannot interpret anything, it simply tries to do it's single job.

3. The ECM takes the signal from the MAF and determines the status of the engine (idle, cruise, etc) it then goes to the table to get it's air/fuel ratio so it can adjust the injector pulse width.

4. People have mentioned the 8 bit register used for airflow. The max value for an 8 bit number is 255 period. The only way to make it higher is to use more bits (i.e. 16 bits). This would involve changing the circuitry in the ECM itself, I believe, which is a little beyond the average DIY person.

With all this said, the easiest way I see to adjust/tune for higher airflows is to simply modify the fuel map/injector pulse width. Since your engine is now at a higher flow rate, simply adjust the fuel/pulse tables to allow a higher fuel rate for a "given" airflow.

My theory for this would be to calculate the airflow your engine can now flow. (This I'm not quite sure how to do yet) and compare it to the "stock" airflow. Take the percentage change of your new airflow rate and use that to adjust the fuel rate/pulse width by the same approximate amount.

I may be way off base on this so don't flame me LOL.

BTW FYI, the Chevy TPI Swapper's guide says the "theoretical" limit for MAF TPI is 325 HP. I find this hard to believe judging by the cars I've seen on this board but that's their opinion. hehhe


------------------
Randy
84 Trans AM LG4, 700R4 T-tops
84 Z28 L69, 5 Spd, T-tops
"Don't sweat the petty things...Just pet the sweaty things"


[This message has been edited by Wolfcoast (edited March 18, 2001).]

 

Madmax: True, you probably never will be over 4500 rpm except at WOT, so it is kind of a moot point.

Vader: Please tell us what we are missing that is so obvious please...

The only obvious solution I can think of would be to change the units on the measurement, say to kg or something. But that would involve rewriting a good deal of the code I would think.

88IROCs: Keeping the ECM in closed loop isn't that hard. You just simply need to set the %TPS to Enable WOT array to 100%, and you can basically floor the car and not go into open loop.

 

wolfcoast,
yes that is what I suggested doing to the fuel map tables. I also suggested increasing the maf range by other methods above.

88,
the units conversion sounds like a good idea, but vader should let us know?? soon?

 

Several weeks ago(on a very sleepless night) I was roooting around deep in the $32 hack, and a thought occurred: the ~165 ECM was not originally designed to interpret an analog signal representing airflow, rather it was designed from the get-go to use a digital(FM) MAF. Apparently, if I read the hack correctly, the ECM could distinguish a range of 64K Frequency Counts(FCB's????). However, the digital MAF's that were available when the ~165 was being designed(1983 - 84?) were of the flapper-valve type. These units tend to be fairly slow in response and restrictive in flow. When the hot-wire MAF's became available they seemed to solve both of these problems, but introduced a new one: how to convert the analog output(VDC) into a digital output(frequency counts) that the ECM could understand. Again, going deeper into hack, I found a number of clues that that is exactly what is happening. Conversion factors in the PROM appear to convert the VDC into FCB's, which in turn are converted to gms/s via the MAF scalars in the MAF tables.

I've toyed with the idea of changing the conversion factors, but am quite daunted by the task of identifying all of the ancillary calculations which would need to be identified and modified to make it work. Forget one step, and it could take month's to correct.

Maybe Vader can tell me I'm looking for an overly-complex solution to an easy and simple problem. Or maybe I'm just babbling incoherently to myself(seems like, anyways).

 

Vader, how about that explanation u were going to give every1 on this??

------------------
Looking For:

87 IROC-Z 350 TPI
84 TRANS AM 305 H.O.

 

88IROCs hit the nail on the head...almost. Just as the hot-wire MAF was a great improvement over the original flapper units, the new digital MAFs (as used on the LT1, LS1, etc.) are significantly better than the hot-wire MAFs. You see, the MAF does not always maintain the wire at a constant temperature. It TRIES, by design, but it is always a little behind--it takes some time for the wire to heat back up to the 'constant' temperature. Morover, there are conditions where the MAF simply cannot change voltage fast enough to keep up with changes in airflow. The new digital MAFs are supposed to correct this...or, at the very least, improve the situation dramatically.

There are other benefits to the digital MAFs. As far as I know, us 3rd-genners are the only ones using our particular MAF design. On the other hand, every F-body that rolls off GM's assembly line, as well as every F-body that's rolled off the line in the last 7 or 8 years, uses a digital MAF. Thus, there is a much greater supply AND a much greater demand for digital MAFs--basically, we'll be able to get them easier and cheaper, for some time to come. Finally, the hot-wire MAF is pretty much stuck with the 3-inch diameter housing. Digital MAF's, however, are available in much larger sizes, thus rendering null and void the argument that the MAF creates a restriction in the intake.

Now...what does it take to use a digital MAF on our cars? According to what I have read, there is a flag in the PROM to select MAF type (analog or digital). Over on the PROM board, there was a 3rd-genner who set that flag to 'digital', plugged in a digital MAF from at LT1, and...it worked! That is, until the MAF output reached a frequency beyond what the ECM can receive. This is actually what the GN guys are doing now--using a digital MAF with a translator (which converts the frequency output of the MAF into a frequency range that the ECM can 'understand'). So, to answer the question, just one simple modification to the PROM code, and a translator.

And finally, to tie all this back to the previous discussion: now that we have larger MAFs, we can use them on higher-displacement, higher horsepower, and/or supercharged engines--engines where the 255 gms/sec limitation is a major problem. Conveniently, Vader and Red Devil have already taken care of that. Good show!

PS: 88IROCs, where did you get the $32 hack? I've been searching high and low for it, to no avail.

 

I think that vaders solution is a carb:-). I swear though, reading this reminds me of reading 'real' hacking messege boards...

 

Can't remember exactly,... either in the /download folder at DIY-EFI or from the EFI guy. The name of the file is: BUA_HAC.pdf. If you've got a broadband connection I could email it to you(the file is 385 Kb). Well I could email it to you even if you don't have bb, it'll just take a while for you to receive.

 

Hey 88IROC,
could you email me a coyp of the $32 hack? I'm getting a TPI setup from an 87 IROC so I think that would be very useful. hehehe
email is wolfcoast@earthlink.net
Thanx,


------------------
Randy
84 Trans AM LG4, 700R4 T-tops
84 Z28 L69, 5 Spd, T-tops
"Don't sweat the petty things...Just pet the sweaty things"

 

So there is something u can do about it.

------------------
Looking For:

87 IROC-Z28 350 TPI: The car I want.

84 TRANS AM 305 H.O.: Another car that would be OK to own while I look for the IROC-Z!!