Quote: Hope you don't mind my 2 cents. Dual maf's that output frequency instead of voltage is not the way to go. If your ECM supports 0-5V based MAF's, you can go quite large (90mm) bosch part number 13-62-1-311-950. Its expensive and unlikely that you'd find one in a junkyard because its for the BMW m5 series, but a 90mm MAF is certainly big enough. i saw this on the diy-efi mailing list today. i tell you this is a great idea. does anybody have the flow rates on this bad boy?? if so this is the problem with maf restriction solved forever. the part about exspense sounds discouraging but hey whats to say looking into it isa bad idea ?? would hurt to check it out. so aybody got info id like to hear about it. this would be perfect with $32b as you can spec inj pulswidth. its gonna take a bit of tunning work but the code limit is 255grms a sec but its really 5 volts. kind of like a 3bar map. any ideas thoerys?

I saw the same thing there. the only real trouble is going to be in the source code. Since the TPI Bosch MAF code maxes out at 255 and the newer one maxes at 512, I'm thinking you'll need a whole new MAF table. I don't know the size of the MAF table for the BMW that that MAF is used in but if it were the same size you might be able to graft it into the $32B code.
Next would be the duct work for the sensor. Easy enough to fab but the stock filter inlets would be too restrictive at this point I think.
Might be a fun winter time project.

I seriously don't see any real reason for MAF guys to stick with MAF anymore. The parts needed to convert to SD can be had for $100 or less (used from the boneyard) and it only will take a couple hours to repin the harness. There really is just no reason to stick with MAF. One bad MAF sensor more than makes up the financial investment.

Tim

Seriously. It will likely take you less time, Hassle, and Money to convert to speed density than it will to even diagnose most MAF related problems.

Yes, true....however I've been finding that the boneyards don't want to cut off and sell just the connectors for the 730 ecm along with the ecm-they want to sell you the whole engine harness!
Unless someone has a source??Sure would be appreciated!

Go to a pick your own style yard. They fit nicely in your pocket.

If you are converting from a 165 then you need not get the connector,just repin your own.
I did it in a few hours with a bobby pin.

I agree I had more successes tuning my car when I switched to SD. And in my opinion SD is a lot easier to tune.

Why does anyone do anything that is difficult? Because they can and they like doing things like that. If mankind were to have stuck to what was easiest and simplest, where would we be? Driving horses and buggies on square wheels.

ok im gonna blow your head off now. maf is easier to tune. i wouldnt worry to much about code resolution either its complete overkill in the lower load ranges for sure. i was just curious if anyone had seen this maf. geuss not. and speeddensity runs good but so does maf once you get a good grip on whats going on.

info from diy-efi ftp site:
ftp://ftp.diy-efi.org/incoming/packard.xls

Part No. Description Function Minimum Qty Desired Qty Price Cost
12045575 Black 32 pin ECM Connector 0 25 0.7962 $19.91
12045889-B Terminal Position Assurance 32 pin ECM Connector latches 200 0 0.1255 $-
12045890-B Terminal Position Assurance 32 pin ECM Connector latches 100 0 0.1255 $-
12047900 Terminal Position Assurance 24 pin ECM Connector latches 0 0 0.4862 $-
12047901-B Terminal Position Assurance 24 pin ECM Connector latches 100 0 0.2433 $-
12047946 Black 24 pin ECM Connector 0 25 0.7515 $18.79
12052052 Yellow 32 pin ECM Connector 0 0 1.1678 $-

12089660-L Pins for ECM connectors 200 400 0.0734 $29.36


everything is available thru www.powerandsignal.com

Financially, Speed Density is better.
For reliability, Speed Density is better.
For high flow, Speed Density is better.
For idle characteristics, Speed Density is better.
Need I go on?

Many people favor the 'underdog'. MAF is the underdog. Thus, of course it will have supporters that scream 'GO MAF!, GO 165!'. However, MAF cars can run fast. Supporters of the 165 seem to think they have something to prove ... that MAF cars can go fast. However - nobody is saying that they can't. MAF cars can AND DO go fast. 165 supporters need to understand that. Sure, the MAF cars can go fast. But, what happens when you get a Trouble Code that points to a busted MAF or the need for a new burnoff relay, etc. What happens when you are is running like crap on a long drive because the MAF crapped out on you? What happens when you install a big cubic inch smallblock between the fenders and need a bigger inlet tract? What happens when you install a huge cam and there is reversion across the MAF wire?

I think that if you have MAF and no money then you should stick with it until you need to invest money in a new MAF. At that point you should immediately swap to speed density.

Tim

Not really. In the 17+ years I have owned my car the MAF was replaced once, under warrenty. (It ingested a lot of water)
No argument there. Thats why people are looking into thngs like a larger MAF and code to go along with it.
I disagree whole heartedly. I have a MAF car, when it is idling you really have to look at the engine to see if it is running, it just quivers ever so slightly while idling.
And S/D supporters are just as rabid, otherwise they all wouldn't be telling everyone to ditch the MAF in favor of MAP.
You replace it, just like anything else. A relay isn't expensive ($14)
The same thing that you do if the MAP takes a dump on you. I personally HAVE been on a long drive (1400 miles) with a MAF that was acting up (turned out to be the connector, not the MAF) And the car suffered no ill effects from the MAF problem and drove fine.
That is what the first post was all about, a bigger MAF.
To each his own. I'll be sticking to MAF though

One last thought to mull over.
If MAF is so horrible, why did GM go back to a MAF system and why does almost every other car mfg use a MAF system in their engines? Cost isn't the answer either, there was no price difference between a MAF car and a S/D.

hmm thanx for the support morely.most maf problems ive seen to date are due to the misunderstanding of how to tune it.

In the newer GM cars that use a MAF sensor ALSO have a MAP sensor too. It is a completely different setup and can not even be compared to the computers in our cars. These newer computer setups still use SD calculation to calculate fuel.

Some people get lucky.

Of course.

The idle spark routines for MAF cars are nothing like the SD cars. Period. Hmmmmm. I wonder why MAF cars have 128 EPROMs and SD cars have 256 EPROMs ....

They are being told that for good reason. I've tuned both systems. Speed Density is better on thirdgen f-bodies.

Another thing to go bad

MAPs rarely if ever take a dump. MAFs take dumps A LOT more than MAPs do. Plus, there is no comparison. MAP sensors are cheap when purchased new and are plentiful in boneyards because the same sensor was used on tons of different cars.

The fact is - the MAF had to be replaced.

As you should. I say convert to SD when you have a reason. If you don't have a reason then don't convert.

Again - you are perpetuating an assumption. NOBODY SAID THAT MAF WAS BAD! Furthermore, the new MAF systems are rediculously better than the thirdgen systems. If somebody could provide a MAF that could flow huge amounts of air AND A WAY FOR THE THIRDGEN MAF MASKS TO READ GREATER THAN 255G/S then MAF would probably be a great setup on a thirdgen. I'm sure that somebody will find a MAF that can flow more ... but, you aren't going to find someone to rework the $32, $32B, or $6E to have the g/s as a 16-bit value - and then give you the code for free.

Fact is - with high power MAF systems you have to force power enrichment early and supply extra fuel via the PE tables. Speed Density doesn't have to do that. I wonder why DFI uses Speed Density?

Tim

What exactly do you base this statement on? I've owned 3 MAF cars, and there is another one here that isnt mine. I replaced the MAF on one, trying to chase down another problem, and not to my surprise there was nothing wrong with it, so I put the original one back on. The dealer made the mistake of replacing the one on my 85 more times than I can count, and turns out it was the module... no real surprise there. I never replaced it in the time I owned it, and neither did the next owner. I wouldnt go around waving a banner for 85 MAF cars, but the MAF itself is basically the same. Not one of them has bit the dust. One of them is 17 years old, another is going on 13 years old, and the other is a 9 year old reman because the engine and wiring was there, but the MAF wasnt. It hasnt gone bad either.

I sold parts for 6 years, the only MAF sensor I ever sold was to myself. I sold a MAP sensor to a friend, a failed experiment someone had sold him on. I really think the only reliabilty problem is careless hands.

I wont disagree a MAP is cheaper, but if they dont go bad, it doesnt matter.

I don't want to act pro SD or anti MAF ,In my opinion my car when it was operated by the 165 was much easier to get pretty flat BLM's across the board but i also wasnt maxing out the Gps either.
When my oldman came over when my car was apart and stuck his finger in the MAF to get those "cob webs" out.......
It was much cheaper for me to swith to SD as opposed to
buying a new MAF and I gained a tenth in the process.
Probably due to the restriction loss.
MAF in my opinion is a good system,but if it goes bad or you are looking for that extra tenth and much more tuning ability its time to switch..

I have known severla people with MAF cars and mine was the onlt one that had the sensor replaced (water in the MAF isn't good)




The fact is - the MAF had to be replaced.[/b][/quote]
No, it didn't. The connector had a bent pin, a little tweaking with an awl and all was/is well.



Cheaper parts and it is the system that was the "latest and greatest" when those systems were devloped.

So what was the latest and greatest when thirdgens were last being made?

I'd love to use a newer system that's MAF/MAP based with SFI, rather than what thirdgens were originally developed with. But unfortunately, since I'm going for ease of installation and use, circa 1992 technology is the latest I can go to for now. That just happened to be an SD setup.

I won't contest that MAF is better from a 2003 all-around point of view. But from a 1992 GM point of view, SD is a whole lot better.

You don't even have to switch permenantly. Mike Davis' prominent site on converting is actually all about making an adapter for easy switching between the two setups so that he could make a direct comparison. If you [no one in particular, just ppl in general] follow his experiment exactly, maybe you'll have a more two-sided view of things.

If mankind weren't looking for easier or simpler ways to do things, he wouldn't have developed anything past horses and buggies. Sometimes you have to take a step backwards to take two forwards.

MAN!!!!!!

Many of the heavy hitters are in on this one.

IMHO, while I was tuning my '87 MAF car with its restrictive air flow potential, I was thinking along the lines above that Traxion said. BUT, after doing the PCM tuning on my '99 MAF car where I achieved 400RWHP, I am having second thoughts.

MAF cars can run really great. Stroked LS1s are using MAFs and putting down 500+ HP! If you (ECM or PCM) has a very good measure of the air going into the engine, the ECM or PCM should be able to acheive the desired AFR at any RPM and load case. With a MAF, you have a better measure of the amount of air going into the engine, MAP cars do not measure up on this point. (Excuse the pun.)

However, the MAF on my '99 car in much larger in diameter (90mm). I have forgotten the MAF diameter on my '87 car, but I know that it is smaller, maybe 75mm. Flow data from a company showed that a modified '87 MAF can flow 750cfm. Carb cars flowing 750cfm can produce over 400HP. SO, why cant we (the guys with '87 MAFs) produce 400HP with a MAF?

Its not that they can't,because they can. but they generally
exceed the 255 gps limit causeing you to use the power enrichment adder to make that fueling - which i think is no big deal, but if you "can" produce 400+HP with 750cfm how much would that 400 HP car make without that restriction in its path?

the 255grm sec limit is an illusion the real limit is 5 volts.the ecm cant read more then 5 volts. 5 volts in the $32 $32b $6e code is FF or 255. so all you need to do is grab larger maf and rescale the tables with $32 $32b.not a big deal.

doc where is newport mich. im over in oakland county/white lake.

funstick,

Where do we find a larger diameter MAF for our $32 cars?

The MAF on my '99 is not siutable for my '87, these two MAFs work differently, the '99 MAF puts out frequency, the '87 MAF puts out counts (voltage). Can we convert frequency to counts somehow? We need a EE here.

I live between Monroe and Newport, out near lake Erie, just South of the nuclear towers of dome.

BTW:

The '99 MAF table in the PCM goes from 1500Hz to 12000Hz. The max air flow value allowed in the table is 511, however my recalibrated MAF table peaks out at 459 gm/sec the min value at 1500Hz is 2.55gm/sec.

I have never seen a frequency output from the MAF greater than 10500Hz, thats at WOT 6300RPM. Thats where I pulled 400.3RWHP.

apperntly M5 bemmers use this big as maf. which ones i dont know. i will make it a point to find out however. im gonna assume a 90mm maf is good for close to 800cfm. ?? that sounds right to anybody else ?

75mm (85-89 maf)= 750 cfm
90mm= more than 800 cfm I'd bet, I think we might be looking at closer to 1k.

And in theory the 750 cfm maf should be able to make quite a bit more power than the 750 cfm carb, since the carb's cfm is air and fuel mixed and the maf is strictly air flow.

my current reasoning is the 75mm stock maf actually flows 560cfm ore somwheres around there.

I'm talking a descreaned and gutted maf. I believe the new maf's only have 1 screen, covering the inlet side, not sure on the fins though.

yeah but gutted descreened mafs tend to have issues with flow irregularity.im assuming bosch worked pretty hard at keeping the new mafs more linear. im still trying to figure out which year m5 has this maf. i post details soon.

As said in a few posts above yours:
In the newer GM cars that use a MAF sensor ALSO have a MAP sensor too. It is a completely different setup and can NOT be compared to the MAF computers in our cars. These newer computer setups still use SD calculation to calculate fuel.

It is my understanding that the LS1 MAF cars calculate the required fuel from the MAF signal and other adjustments. The MAP sensor is primarily used when the PCM goes into limp home mode. The OBDII programing is very very good, much advanced over our 3rdgen stuff.

The latest PCM programming is much more robust and the intake much less restrictive, but they are stiff MAF cars. There is no better way to measure the incoming air than a good MAF.

hmm the whole argument is silly.

maf tells the ecm directly grms per sec of airflow

s/d calculate grms sec of airflow.

they booth do the same thing yet go aboiut it in different ways.the measure airflow.

doe maf have an advatage sure does. its not subject to low engine vacum problems like map is. also it dont need bost multpliers for boost it just need to see the change in load and use the correct values.

s/d has it own advanatges in that it is sort of easier to tune in a few aspects. but then it also seem to be mre accurate at predicitng load.

its hard to say however maf can be made to work if your willing to put the elbow grease in.and you dont need alot of grease.

I forget where I read it but I believe the new LS1 cars were actually faster in the 1/4 mile when the Maf was removed. The ecm went into speed density mode and the biggest problem with an LS1 is the intake, not the exhaust. A good example is seen with larger intake duration/lift cams than exhaust and the power they produce even with stock LS1 ex. manifolds! I'm not sure if this works or not but it would make sence since SD is faster reacting to engine demands. MAF seems to be the easiest for boast applications since it's still measuring the amount of air coming in before boast. Again there is that issue with responce.
Given my experience I would have converted the world over to speed density by now. Like funstick said though, a MAF doesn't have to worry about the cam duration and overlap so much. This makes for a few less hassles. Good luck with MAF, good to see it people still working with it. Makes me feel better since I'm one of the last few to still be using TBI .

just a funny idea how about using a maf with tbi.you coulkd do it its not hard.

So, what is the stock inside diameter of our MAFs???

I think that my '99 is 75mm, but the aftermarket units are 85mm, like the GMAF that I am using.

75mm is stock thrigen maf size. there are some thing restricitng the maf however a large cooling fin array for the wire heater.

Yeah, would be nice if it wasn't so complicated! TBI injectors fire WAY different than TPI so it's not like this is a simple code change.

hmm maybe i know how to set the bit for tbi?? theres is one in both $6e and $32b in the fm word bytes.

Flow Tests

The following airflow tests were performed on the University of Northwestern Ohio's SuperFlow SF600 Flow Bench. All CFM values are corrected for airflow at 28 inches of water. Injector flow rates are flowed at 43.5 PSI on an injector flow bench using test fluid with same density as gasoline.

AirFlow

Stock TPI/LT1 48mm Throttle Body w/o airfoil -- 783.0 cfm

Stock TPI/LT1 48mm Throttle Body w/ airfoil -- 821.9 cfm

TPI/LT1 52mm Throttle Body w/o airfoil -- 848.9 cfm

TPI/LT1 52mm Throttle Body w/ airfoil -- 898.8 cfm

Stock 98 Camaro 3800 II Throttle Body -- 554.3 cfm

Stock TPI Bosch MAF sensor w/ screens -- 517.8 cfm

Stock TPI Bosch MAF sensor w/o screens -- 658.4 cfm

Stock 87 GN 3.8L Turbo AC MAF sensor w/ screen -- 584.2 cfm

Stock 86 2.8L AC 5-wire MAF sensor w/ screen -- 576.2 cfm

Stock 96-up AC 3100 V6 MAF sensor w/ screen -- 616.4 cfm

Stock 96-up AC 3100 V6 MAF sensor w/o screen -- 670.7 cfm

Stock 94-up LT1 MAF Sensor w/o screen -- 719.0 cfm

Stock 85-87 Firebird TPI airbox mid piece -- 499.3 cfm

Stock 4.3/5.0/5.7 2bbl TBI complete -- 574.1 cfm (dry)

Stock 4.3/5.0/5.7 2bbl TBI w/o injectors -- 584.7 cfm

Stock 3800 vin L throttle body w/ screen -- 419.1 cfm

Stock 3800 vin L throttle body w/o screen -- 444.8 cfm

4bbl MPFI Holley Throttle Body -- 1287.6 cfm

In-Tank Fuel Pump Flow Rates

92 Buick Ultra 3800 Supercharged High Volume AC Delco EP311

36.6 Gallons Per Hour @ 43.5 PSI

25.8 Gallons Per Hour @ 60.0 PSI

Injector Flow Rates

3800 vin C injectors -- 19.0 lb/hr

3800 vin L injectors -- 21.2 lb/hr

3800 SC vin 1 injectors -- 29.0 lb/hr

3800 Series 2 injectors -- 21.2 lb/hr

86 Vette RP 5235211 TPI injectors -- 21.6 lb/hr (Bosch design with plastic tip)



87-88 Vette RP 5235302 5.7L TPI injectors -- 21.6 lb/hr (Bosch design with aluminum tip)



85 5.0L RP 5235047 TPI injectors -- 19.3 lb/hr (Bosch design with plastic tip)

thanx for the info. but what does it all mean. from looking at your charts i do believ you need to calabrate your flow bench. the tpi camaro and the turbo buick( the bosch sensor) both use the same MAF. with varations like that in flow reading i would say check the flow bench something is afoot.

I was thinking the same thing about those 2 maf's. Maybe the GN wasn't stock, a larger replacement that the previous owner didn't know got replaced?!?!
As for the TBI flow benching, it makes very good sence that the injectors don't cause much disrupiton but what about wet flow at like 85% injector duty cycle with 65#ers. That would be useful info along with stock air cleaner piping! The stock TBI intake has that silencer ring that directs the air into a velocity stack of sorts. Only trouble with that is the injectors standing directly in the way. It's almost like they were trying from the factory to make TBI out to be bad on performance!!! I guess that's what you have to do to make sure everybody goes and spends the extra money on you're expensive R&D from TPI projects . Fools, lol

RBMZ28, thanks for the info. Good work.

RBob.

Might actually trying looking at them before making any statements assuming that just because the out sides look similiar that the guts have anything in common.

There are several different series of MAFs that use similiar cases, and entirely different guts.

there sure are sevral type of mafs. there 2 for sure Voltage based and FQ based.then there are housing variations for sure. but i did a bit of cross refing and saw that the gn maf an tpi maf are the same. in term of aftermarket replacement. thats not to say however that the factory didnt have minor variations.

from what ive seen so far there are basically 6 mafs around.

the ones found on 2.8's, 3.8 sefi non turbo, 5.7 tpi, gn which is supposed to be the same ??, there a few other apps i cant think of as im typing this but in all 6 models of maf with 2 different output schemes. what i cant figure out is why didnt gm just use the FQ based maf on the TPI and use the bosch instead ?? i never will understand that move.

anyways grumpy good point as always.

Because the Bosch style voltage maf was the first one, there wasn't a freq based maf in 1985 that could be used.

Also I think the Bosch design (voltage) is supposed to be the best there is.

Got a Brand and part no.?
I'd like to see that one.

I double checked, you're right, they're different. It's funny because I was just about to say nope, same part number but then I looked closer in the book and it's a 1, not a 4,
Borg Warner: GN part #;57851 , Camaro part #;57854
Just thought I'd clear the mix up.

check Tomco.the local auto parts store listed them as the same. they should be the same. there both 75mm 0-5v bosch MAFs. anyways the local advance said the were the same. that doesnt mean that i have had time to pull out a good wells book and check it against gm part numbers been to busy working 12hr days to mess with it.

bigger point is that if the GN maf does flow more air grab one up and run with it. also this whole topic is about a bosch 90mm maf. would be nice to get a price on one. when im working tommorow ill try to get a call in to bosch ( down the street ) and see just how much these bad boys are. they have the distrotbution headquarter in Novi Mich. just 15 minutes from me.

How do we convert cfm to gms/sec???

I know how to convert lbm/min to gms/sec.
gms/sec = (453.5/60) * lbm/min

So I need the weight of a cubic foot of air???

DAH!

Who can help me?

AND is there a published article on the above flow rates?