Ok, everyone says that the maf tops out at 255 grams per second. Very nice, but, vaguely meaningless. What does that translate to in CFM????? (at standard temp, and pressure.....) THAT would be a little more usefull. (no, I don't want to do the math to figger it out.......)

 

Its around 440cfm@STP.

Im not gonna bother with the math either, but I'm within a few cfm of the actual number.

The actual 'limitation' may become a thing of the past real soon here... keep a lookout.

 

Yes Vader has been talking about this, once that is fixed we won't have to listen to all the SD guys talking about their "advanced" ECM's.


------------------
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 still look for the IROC-Z!!

 

eek, advanced or not, lets not rip on each other now. MAF and SD are different in their own ways. Lets keep it this way and forget who thinks what is more advanced.

------------------
89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Gutted cat
-!AIR

[This message has been edited by branz28 (edited April 11, 2001).]

 

Beings how I have a MAF, what is Vader up to? I didn't know he had a plan, someone please clue me in.

------------------
Rob
'86 TA 305 TPI
Gutted MAF, Ported Plenum
TB Bypass, Home made Cold Air Intake,
Edelbrock T.E.S.

 

Ok, given the value for max airflow... (please correct me If I screw up the math...) that translates to 760320 cubic inches of air at max flow. That means a 350 cubic inch engine, operating at 80% volumetric efficiency would overrun the MAF at 5430 RPM. For most purposes, that seems adequate to me..... (my engine CERTAINLY does not spend much time there.......) I am also fairly certain that there are folks out there that regularly go past 5400 RPM in the course of the day. These are the folks that need to be most concerned about upgrading.

Does this look right to you folks?

12^3*440 (convert cubic feet/minute to cubic inches per minute) / 350 (to get a number that represents rpm at max flow at 100% efficiency) / .8 (to correct to 80% efficiency) * 2 (since this is a four stroke motor) = 5430 (approx)

So, increasing VE will reduce the max RPM before overrunning the MAF, (blowers and such) and assuredly require an update.

Next question.....

Is the 255gm/sec value the max the MAF will report? or is it the max the ECM will accept?

 

Yes, but how much time do you spend at that rpm while your are NOT at WOT???

You go open loop over whaddisit? 70% 80% throttle so what difference does it make. I don't 'cruise' down the street at 5600 RPM at light throttle expecting great gas milage.


If you are adapting to a monster 502 cube or something then....


Port your sensor. Removing the fins allows more air around the sample tube, therefore not only improving CFM and reducing restriction it also lowers the amount of sampled air which doesn't nessisarily have to be compensated because GM WOT is too rich to begin with (stock).

OK a lot more radical..... Why not get out the f'n dremel and cut the MAF apart... It's like what 3" OD or 3 1/8" OD if i'm not mistaken??? leave the electronics and sample tube (DO NOT try to unbolt the parts)

Measure the hole you are going to need to angle the sensor tube up into a larger piece of 4" or what 4 1/2" or whatever PCV pipe and quicksteel it in to place. Paint the tube black. Trick or what? How much money and tears was spent there???

Ok, you DO NOT want to go overly large (the stock meter is fine for just about anything.... How much time do you spend over 3,500RPM and under 70% (or 80%..who cares)...


Breaking it down:

1. If your motor is stock or fairly modified, a stock or ported MAF works great.

2. If your motor is seriously modified 350(norm asp), why did you waste your money doing that when more cubes can be had(and more power by an increase in cubes. (This sentence only applies to those who feel limited by their MAF, are normally aspirated, and feel they do not need to burn/ have one made a PROM for their combo)

3. OK you have a killer 406 cube small block (Or a 350 on MASSIVE doses of SUPERCHARGER) and the MAF becomes a restriction, it runs like SH#t because it's too rich at idle, you did all this work for almost nothing because the chip is stock, you spent countless dollars on trick speed parts and now you find out you NEED SPEED DENSITY because the MAFS a restriction. OK the money you spend on conversion and TIME spend doing it, you could have bought the PROM burner, a 5 and some odd fraction" piece of PIPE and started retuning with MAF. That saves all the labors of conversion, and if you own one of the HOT motors on the list, you would surely be into burning your own chip anyway.


I'm not slamming SD....

I'm not condemning MAF...

If I had SD to start with I'd sure as hell would stay with it... But I don't, so I'll stick with MAF because switching would cost more than a bigger piece of plastic pipe.

Call me cheap, but I do nothing of the sort..

Now some SD provoking A=H who swears by god every MAF car should convert because they did, and are burning their own PROMS (because they HAVE TO BE VERY CLOSE WITH SETTINGS)

Us MAF guys can alter a table or two and be good 'nuff left alone, which is why there's no money in burning MAF PROMS, not saying their not needed, but we just have to be in the ballpark, you have to be right on or else.


Basically I'm tired of hearing MAF vs SD and had to blow off some steam since they both work grat, have their own probs and limitations (What about radical cams? No vacuum you might as well toss that friggin MAP sensor on the street and run it over and go with Alpha N metering)

Realistically, If your bitchin about this, go buy a carbeurator, cause if your bitching about this, a carb or Alpha N metering is your only true option for that all out 'street car' you own that just has to have (fill in the blank with MAF or SD... whatever)



[This message has been edited by JoelOl75 (edited April 12, 2001).]

 

While your arguments have some merit, you are missing the point. On a stock MAF car, it would appear that the limitation for the maf is at around 5400 rpm. Even though the computer goes into open loop at WOT, it is STILL using the maf to determine airflow, and this is what it uses to calculate injector pulse width. If you go over the value the MAF can accurately report, then the computer is just guessing how much fuel to give. (yes, you can get around this by changing fuel pressure on a maf car to compensate..... and I have already seriously modified my MAF sensor) Modifying the MAF does NOT increase its ability to report airflow, it only allows it to flow more air.

What I would like to know now is....... Is it the MAF that cant report higher than 255 gm/sec, or is it the ECM that can't accept readings higher than the 255? Or both?

 

255 is the limitation of the ECM (actually it is the limitation of the calibration [$32, $32B, $6E, etc]). The MAF values are stored in 8 bit as opposed to 16bit values. The high value for a 8 bit value is 255.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Thanks Tim. That is what I was wondering. I quess the rest should go on the prom board...

Thanks All.

 

The STOCK MAF may only flow around 440cfms but with the screens removed and the fins cut off it will flow roughly 650-700cfms!!

Also, you have to remember that the MAF is NOT the most restrictive part of a STOCK TPI setup!! The intake is....and the plenum is very restrictive also!! Even with the stock MAF flowing 440cfms, you're not using ALL of that airflow because of the intake!! Even if you increased the cubes and ported out the plenum and intake, a modified MAF is still sufficient enough!!

Besides, Granatelli is working on a way to adapt a 4th gen MAF to our thirdgen cars anyway from what I hear!!

 

There are some trying to get around the ECM BS with MAF cars, and I think Vader and others will do it, and that, will be cool.

------------------
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 still look for the IROC-Z!!

 

Yes, you can improve the air flow characteristics of the MAF sensor, but, that does NOT change how much airflow it can report. Even though the MAF can flow 670 CFM, the max REPORTABLE air flow is 255gm/sec, or 440 cfm.

And that is where the problem lies.......

 

Yes, if u can change how much airflow the ECM can take, then modding MAF's or buying SU-145's will become really good things for MAF cars with LOTS of mods that need that much airflow. It will be so cool when some1 knows exactly out how to do this.

------------------
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 still look for the IROC-Z!!

[This message has been edited by IROCZTWENTYGR8 (edited April 12, 2001).]

 

"Never underestimate the power of the Dark Side"

Patience... I only have so much spare time. The spare ECMs are already plugging away on the test bench, and intial results are promising but not yet proven to my satisfaction. There will have to be some programming involved, but the hardware is surviving the surgery so far.

What kind of power do you think you could make with a metered air flow of over 500 grams per second of intake air? Would that be enough to satisfy you guys in the 400SBCs at 7,800 RPM or what? Of course, you'll need at least 36 lb/hr injectors to make some REAL power with that kind of air flow, and this may not be a very street-friendly setup.

------------------
Later,
Vader
------------------
"What a Day..."
Adobe Acrobat Reader

 

Exactly what vader said.

And porting and/or seriously modifying the MAF does change its reported airflow because it is NOT measuring all the air that passes through it. If more air passes AROUND the center tube (remove the fins/ bigger external tube), the number will be LOWER (possibly 330 gm/sec for 255 as example) and the difference (because it will be lean) can be made by PROM and/or fuel pressure changes. Just because it reads to 5,400 or so RPM doesn't mean it can't handle 6000 or 6100 rpm or more.

Now I know this method of 'retuning' the MAF causes granularity in the readings. But in most cases this is all un-nessesary anyway because when I use the word 'cruise' I mean at light throttle at 6000 RPM and expecting closed loop 14.7:1 fuel control which is crazy. I wouldn't care if the MAF reported to only 3,200 because I don't 'cruise' around over that.

 

Whoops, my mistake, you are correct Joel....

It would require changes to mixture for open loop operation in the lower rpm range as well, (again, this could be addressed by fuel pressure, or prom changes...)

Finding the EXACT amount of air that is flowing thru it, after modifications, as opposed to what the MAF thinks is flowing thru it would help alot, anyone have any ideas??

 

Anybody read the most recent carcraft where they said that there is a company that makes a translator for the TPI engines so that a bigger FORD MAF can be used? I read this and was like ... wow.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

using a bigger MAF would be nice, but, we would still need to get around the 255 gm/sec limitation in the ECM.......

 

Tim, I believe that's Granatelli that's working on that project as well!!

 

ok so let me get this straight...you can get a MAF to flow decently but the computer will only read around 440CFM? why would anyone do this then? wouldn't that cause you to lean out?

------------------
Originating member of the SJNEP Crew
Member of the Jersey Fbody Crew(JFA)
Check out MyGTA Nicknamed:The Big Red Machine
***AOL IM RiceEatinGTA***
Moderator at www.transamgta.com
"What does not kill us only makes us stronger"

Tony

 

There really is no point in doing these mods to the MAF since the ECM can only read 440CFM!! It wouldn't make the car lean out tho' because the programming in the stock GM ECM is already set a little rich!!

About the translator though! I read it again yesterday...it IS granatelli that has made this translator! I couldn't find a place to order it tho'! Maybe it's not out on the market yet but they had pictures of it! Apparently it has some sort of controls on it as well so you can set lean/rich and certain other voltage modes I believe just by turning a little **** built into the translator!!

 

The idea is to get the ECM to be able to read higher #'s so modding MAF's, SU-145's, and other stuff, would work even better.

[This message has been edited by IROCZTWENTYGR8 (edited April 25, 2001).]

 

[This message has been edited by IROCZTWENTYGR8 (edited April 25, 2001).]

 

That is only part of the problem.
On the MAFs there will always be the problem of the mass of the sensoring element. It will always lag behind the actual airflow in any thing other then steady state conditions. ALWAYS.

There is one lil table that you'll never have, accleration enrichment vs MAP. The MAP sensor is a bunch faster in rssponse then a MAF.

I have worked on numerous MAF and MAP systems, and currently have MAF in my current toy, and you just can't set an ecm up to overcome the lag of a MAF system. My current system is a turbo, and I can get good response since there is always a .00001 sec lag while the turbo spools up anyway.
YMMV

 

interesting, interesting....

------------------
89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Gutted cat
-!AIR
-Gutted Air Boxes

 

Lag time on the MAF does not seem to be too much of an issue, for me anyway. The throttle response is instantaneous, and power is smooth throughout the RPM range. I also have an MSD smartbox, and that seemed to make quite a difference in throttle response.....

 

if you guys are concerned with maf grams. you first need to get rid of the tpi. For those that have spent all the money on making the car breath in the upper rpm limit 5500+.


I think a aftermarket ECM like a fast or dfi is the way to go. not unless you know how to write code and make the ecm do what you really want it to do.

MY gn has a maf that from the factory it reads a max of 255 grams.well it being a turbo it's easy to over run that. So Bob Bailey has wrote a extender chip for the 148 ECM so it doubles the maf grams and he does this with a MAF translator and the newer style GM maf's so in turn you can get 510 grams of air. He has just released the extender extreme chip that triples the air flow up 765 grams of air.


that may be doable on a tpi car but instead of doing that for a maf car why not either go with a aftermarket ecm or convert to a SD ecm



some info on the extender chips incase there might be a interest for writing code to get a tpi maf car to do the same.

Designed for 55lb and larger injectors (if your injectors are 50lb. or smaller you need Regular Extreme part number 050EXTCHIP) the Extender Extreme ECM chips are designed to take advantage of the MAF Translator's (and Translator Plus) ability to measure true airflow at high horsepower levels. Instead of the factory 255gr/sec limit the stock computer can now see up to an unbelievable 767 gr/sec of air. This ability to measure all the air entering the engine gives the ECM control to properly adjust injector pulsewidth to maintain correct Air/Fuel ratios for best horsepower under all conditions. Additionally, the Extender chips feature advanced software to permit the user to adjust many parameters that were previously only adjustable by the chip programmer.
The adjustable parameters are:
Shift Light: flashes Check Engine light above desired RPM
DFCO delay: prevents annoying RPM dips while coasting caused by high stall torque converters
Fan Temperature: Select "Street" or "Race" modes
Cruise TCC: Select the vehicle speed for TCC engagement at part throttle
WOT LoGear Spark: Adjust how much extra spark advance is commanded in first and second gear
BLM correction: Adjust for out of spec injectors or fuel pressure, adjusts all BLM's up or down.
System Options: Control the operation of open and closed loop at cruise and idle.
Enable Launch Assist and Lean Highway Cruise mode.
WOT TCC: Control the MPH at which the Torque Converter Clutch engages at full throttle.
Spoolup Fuel: Adjust how much fuel is delivered during the spoolup phase of full throttle.
LoGear Fuel: Adjust the Air/Fuel ratio for Full throttle operation in first and second gear.

In addition to the new adjustable features, the Extender and Extender Extreme chips have the following standard features:

False knock ignore: Prevents false knock from affecting performance
BLM lock at WOT: For more consistent full throttle fuel control
MAF Anti-dropout : To prevent surging and detonation from high airflow readings.
Anti-stalling software: Prevents stalling common with lightweight torque convverters.
And More.

Installation:
The Extender installs just like a regular (stock or aftermarket) chip in the ECM. Be sure the key is off, and unplug the orange power wire near the vehocle battery, under the hood. Remove the ECM from its mounting location (passenger kick panel on a Buick). Remove the cover from the side of the unit. Remove the previous chip and install the Extender. Remove the locking "comb" from the top side of the large connector and insert the small terminal of the supplied wire into cavity D11 as shown in figure 1. Run this wire above the plastic footwell trim to the front end of the console. Attach the supplied tap connector to the gray wire that runs down from behind the radio and disappears under the console. For column shift cars use the gray ashtray light wire. Plug the supplied wire into the tap connector. This connection allows the parking lights switch to select the 'top row' of parameters. Reconnect the Orange power wire (at the battery) and installation is complete.

At this time ensure that the installation of the MAF Translator hardware is complete and the internal configuration switches in the translator are set correctly.

Parameter Adjustment Overview:
The adjustment parameters are stored in 8 locations in the ECM memory and can be seen as the bottom 2 rows of BLM cells for those people using Direct Scan.

The adjustment parameters are changed by using various controls inside the car. These are: Throttle (gas pedal), Air Conditioner, Shift, and Parking Lights (Calpak).

The parameters are numbered 8 - 15.
When the ignition is on and the engine is not running, the parameter number selected for adjustment is shown on the integrator of a scantool, the value stored to that parameter are shown on the BLM (block learn) of a scantool.

Adjustment Procedure:
1, determine which parameter you which to adjust and the new value to be stored.
2, using the A/C, Shift, and the parking lights, select the correct parameter, this is confirmed by checking the INT display for the correct parameter number.
3, The BLM (block learn) display on the scantool will show the current stored value of the selected parameter.
4, Press the gas pedal past half way and the BLM display will start showing the new value to be saved, the farther the pedal is pressed, the higher the number will go (up to 15).
5, When the BLM shows the desired value to be saved, hold the gas pedal at that position and turn the ignition key OFF. This will save the new value to the selected parameter. Turn the key on and verify the correct value was saved.

Feature Descriptions:
Loop Control: The Extender Chips can be configured to run open loop at idle. This can be used to help smooth a rough idle caused by vaccuum leaks, exhaust leaks, large camshafts, bad O2 sensors or other cause. When open loop idle is enabled, the Block Learn value that was previously learned is frozen and the AirFuel mixture is richened slightly. The O2 reading will usually run 780 - 830 milivolts, this indicates an air-fuel ratio of between 14.0 and 13.0 which is perfectly fine. It may have an adverse affect on catalytic converters, so use this feature in off-road configurations only.

Highway Lean Cruise: When enabled, the Lean Cruise option will alter the AirFuel ratio during steady highway driving to approximately 16.5:1 to improve fuel economy. To operate properly in this mode, the car needs to be tuned and running properly. Bad spark plugs, plug wires, or other maintenance issues can cause poor drivability during lean cruise. Lean cruise activates approximately 10 seconds after the Torque Converter lockup is enabled in 4th gear. During Lean Cruise, the O2 reading will drop to 20 - 60 millivolts, indicating an AirFuel ratio of about 16.5:1. Every 8 minutes Lean Cruise will turn off for 10 seconds to double check the block learns are correct.

Launch Assist: When enabled, Launch Assist will improve turbo spoolup while brake-torquing for improved launch when racing. This mode is not intended for street use and does put a lot of heat into the turbo exhaust, headers, and exhaust valves. It does do a good job helping launch a turbo that is too large for the torque converter stall speed. When activated, Launch Assist reduces engine torque and increases exhaust temperature. Launch assist will activate when the throttle is between 50 and 85% and vehicle speed is below 5 mph. When Launch Assist is working, the Check Engine light will flash.

Open Loop Idle = 4, Lean cruise = 2, Launch Assist = 1. Add up and program Parameter 12

WOT TCC: The torque converter clutch can be programmed to lock at Wide Open Throttle (WOT), this usually improves performance and track times. The lockup speed can be programmed from 50 Mph to 105 Mph in 4 mph increments. Lockup will occur at ((Param13 * 4) + 45)Mph. Setting Parameter 13 to zero disables WOT TCC.

Spool fuel: The WOT AirFuel ratio during spoolup can be varied using Parameter 14. For the first 1.5 seconds at full throttle, but below 10 psi boost pressure, the AirFuel ratio is modified by Parameter 14. Default value is 8. Each increment higher will richen the AirFuel mixture by 2%, each increment lower will enlean the mixture by 2%.

LoGear Fuel: The WOT AirFuel ratio in first and second gears can be varied using Parameter 15 Default value is 8. Each increment higher will richen the AirFuel mixture by 2%, each increment lower will enlean the mixture by 2%.

ShiftLight: The Check Engine Light (CEL) can be programmed to light up above a set RPM. This can be used as a reminder when to shift while racing. Program Parameter8 as follows. (Param8 * 100)+ 4800 = setpoint. Programming Parameter 8 to zero (default) disables the shiftlight feature.

DFCO Delay: Vehicles equipped with lightweight or high-stall torque converters have insufficient engine braking at low RPMs for DFCO (Decel Fuel Cut Off) to work properly at low speeds. The result is RPM 'dips' while coasting. By enabling DFCO Delay, the fuel cutoff is only enabled at higher speeds, or when running in Drive instead of Overdrive, improving driveability

Fan Race Mode: In normal mode, the engine cooling fan is programmed to turn on at 175 degrees, and off at 170 degrees. When Fan Race Mode is enabled, the cooling fan turns on at 165 degrees, and off at 150. This essentially leaves the fan turned on all the time after initial warm-up.

Cruise TCC: Cruise TCC threshold can be programmed to lock at 45, 50, 55, or 60 mph. Depending on torque converter selection or vehicle configuration, higher lockup speeds can be more pleasant to drive.

DFCO Delay = 8, Fan Race Mode = 4, TCC: 45=0, 50=1, 55=2, 60=3 (choose) Add numbers and program into Parameter 9

Low Gear WOT Spark. Spark advance in first and second gears at WOT can be programmed to be higher than in 3rd and 4th. Default setting for Parameter 10 is 8which is 2 degrees additional advance. This parameter is adjustable from zero additional degrees advance, to 4 degrees additional.

System BLM correction: Parameter 11 can be adjusted to correct for base lean or rich conditions cause by out-of-spec injectors, incorrect fuel pressure, or other anomaly that affects the Block Learns. For example, if a new set of injectors are installed and they happen to run 10% lean, all the chip BLMs will high by about 12 counts. Parameter 11 will correct 4 BLM counts for each increment. To lower the system BLM counts by 12, raise parameter 11 by 3. Raising the value of parameter 11 richens the system, causeing the BLM's to relearn to a lower value.

 

And that may just be the longest post ive ever seen.

 

I read about half of that, realized how long it was and thought...I'd just await for vader to sort out his set-up. Oh wait, I'm going MS....

 

I'm not going anyware close to the quote button on THAT post!

 

 

It would be great if someone could figure out how to get the ecm to read more cfm's...but I think just being able to use a 4th gen maf would be great since the hot-wire meters are just to erratic in reliability...somelast years...others a few months.
Plus the 4th gen mafs are cheaper too I think... besides with the power enrichment tables in the maf code you can always compensate for what the maf cannot read.

 

I know you can compensate in the PE tables. really is that the correct way to it? no and my reason for saying that is you will have to custom taylor those PE tables for that application.

well what happens when there is a change in weather conditons from summer to winter temps well that tune is going to be out of whack so to speak. If you extend the maf limit the ecm can see with a newer maf and code then the ECM has complete control over fueling @ WOT and the end result you be the tune would be almost dead on most of the time. till something happens and it gets beyond the ECM's control.

why mess around with a maf when you can go to SD set-up and free up some power due to not have to have a maf in the intake tract. they did that for a reason on the 90-92 f-body and for beter driveability.

FLAME SUIT ON.

 

I would think that speed density would suffer more from the change of summer to winter...at least a maf can calculate some of the temp changes before it runs out of resolution. SD is the set-up that is so sensitive to mods after all...Dosen't SD have the same 255 gram limit as a MAf set-up...It only reads pressure,so you go to the fuel tables anyway just like a MAF.. whats the diffrence between a set-up that can only read so much of the air coming in and one that can only read so much of the pressure in the intake...Aside from the actual obstuction in the MAF(which can be cured with a bigger meter) I don't see much advange between the two.. If I'm wrong on this feel free to correct me... Besides they make very large mass air meters...I mean enough to support hp that most people on this board would never come close too...its just the damn ECM tech behind it...I can't belive that someone can make an adapter of sorts that could fix this...There are maf translaters that allow Buick guys to run later model GM mafs,and even translators that allow turbo eagle talons to run late model GM mafs...why the hell can't they get a translater that would allow a thirdgen to use a LS1 meter? The 03/04 Cobra's run MAF meters ...they can make awesome power...MAF set-ups can make great power...and of course SD too...

I like the MAF set-up on my car and would love to stay with it...if it was SD to begin with well thats another story...to me converting to SD would would open up more problems with trouble shooting because then you have to question whether or not all the wires that had to be switched around are correct,ec t..and dropping in a new motor that alone is enough to tune,without having worry weather your ECM is set-up or not. Then you've got all the prom issues...it would be nice if some could just help out the MAF crowd a little LOL.

BTW,take the flame suit off...lol...nothing like a good tech discussion.

 

i understand what your tring to say about staying with what came with the car issue. But for someone to really to sit down and write the code for the f-body maf ecm and make a translator for it is not going to be real profitable for the amount of time and work it will take to build a new code for the ecm to run on. Then there is the demand for it. Being honest here how many TPI car owners out there are really tring to make gobs of power using the old maf and ecm. the number of people will surprise you @ how little there is. most of the guys switch to a carb and get rid of the bull crap that comes with tuning a FI car.

now dealing with a SD i understand that they have there little problems when it comes time to tune them. If i remeber correct the SD ecm can read from 0-100 KPA the map converts that using a 0-5 volt signal to the ecm.

so if i'm correct the SD reading from 0-100 kpa is able to read from 0-30 inches of vacuum. yes that would be correct for since the SD uses a 1 bar map sensor which is actually 29.529 inches of mercury @32 degrees F.

i think bob bailey might offer a translator for the third gen cars i know there is a translator for the LT1 cars to control fuel and timing.

also the a SD would not suffer any from the whether changes since the engine creates it's own atmosphere of vac.

the reason i made the comment about the tune being off from summer to winter is for the fact the temp is going to change. how much oxygen is in the air @ different temps. cause you said that the maf runs @ 255 but there is a PE table. well when your on a PE table it don't change period. but if the weather changes hence temp change the tune is off.

say you program the PE tables for the car @ 40 air temps with low humidty car runs great o2 #'s are in check. well fast forward to a nice overcast day with 90 degree temps and 85 % humidty. and that PE table that your tuned in the colder low humidty day. It's now going to be rich because you have the same amount of fuel flow with less oxygen in the air it's taking in and the ECM has no control after the maf reads @ 255 it's runing on those programed PE tables.

But a SD will have fuel control from 0-30 inches of vac. what i would like to see is how much vac a MAF car is pulling @ WOT when the maf goes to 255. so there is a conversion to be had for grams/second to 0-100 kpa or 0-30 inches of vac. that would be a nice tid bit to know.

my buick with the stock MAF the ecm read about 5 grams of air @ idle with say 14-15 inches of vac.

so if that is anywhere close thats means a maf car @ 255 is pulling 765 inches of vac

my math is this 5 grams = 15 inches of vac

255 divided by 5 = 51

51 times 15 =765

please correct me if i am doing my math wrong.

and would the rise in grams/second be linear to every 14-15 inches of vac? that don't sound rite to me

i guess the only way to know is put a vac gauge on a TPI car and see how much vac it pulls @ 255 grams of air.

 

There are plenty of cars doing just fine running MAF around here, its just that either nobody is looking or they dont want to. And the 255 gm/s limit, isnt.

Gonna get off my soapbox though and let the uninformed continue to be so.

 

FWIW, I had a 165 ECM runing on a bench and experimented with raising the intake limit to 510 g/S (effectively doubling up the "limit"). There were other operational problems that resulted, and while those were addressed to some extent and made to work, I'm certain there would be very little market for an ECM that would be so unique that it required a secondary processor board to handle the rest of the critical I/O. I think I still have that box of hardware sitting around somewhere.

There are easier ways to deal with any restriction that the firmware of the old ECM presents. GM has offered several PCMs that handle the MAP and MAF simutaneously, with no practical firmware limit on intake air flow metering.

 

Can larger maf sensors be purchased for my 86-87 TPI unit?
Who can tweak my chip to work with 110 lobe sep. cam?

Can I do this: Run a by-pass tube past my MAF that will have a butterfly valve operated by a solenoid whose relay will operate off of a vacuum switch. The TPI air flow would flow through the MAF totally until The vacuum switch opens the butterfly and then both paths flow air into the plenum. I am putting TPI in my 84 T/A and on my old carb set up it had a vacuum operated cold air intake on the hood. I was going to use that hardware to make the by-pass tube actuator if the idea will help my flow restriction issues.

please advise

thx

jeff

 

I know there is cars out there that run great after maxing out the 255 limit. but it can run better if the ecm has control over fueling after 255 intead of running on a programed PE tables.

My gn in stock form would max out the 255 limit @ 14-15 psi of boost with a stock turbo. so you add a ported set of heads and a big turbo and your able to max out the 255 limit @7-8 psi. to tune it to run rite after the 255 limit is add fuel in the PE tables just like a TPI car. BUT if you were to say raise or lower the boost. the A/F is going to be wrong because to you tuned the PE tables to a set amount of airflow in the engine.

So now that bob bailey has done his extended chips using a MAF translator and a extender chip my buick now is capable to read 765 grams/S. so that means if i got to the track and i want to turn up the boost i know the ECM is going to be able to add the correct amount of fuel for the added airflow in the engine.

yes you can do the pe tables and it run great. but is that tune going to run consistant everyday no matter what the weather/temp/humidty.

FLAME SUIT ON


I am informed. i understand the limitations also. also it has a lot to do with what you think runs good compared to what i think runs good too. different veiws on that i'm sure.

 

Why can't someone do an "extender" chip for a MAF TPI?...thats all I'm asking.

i don't see any harm in the pe tables...as long as the motor gets what it wants...right?