Ominous 87 Cracks me up!!! Im glad to know im not the only one he argues with!! You Go Ski

 

get this post back on track. Im following it as I was thinking of getting pro top lines for the 418sb Im in the middle of building.

then again I may just get afr's again. they worked in the past.

either way back to the topic.

Tom deff. keep everyone upto date

 

I don't want this post to be locked either, but I just can't stand the SD cheer squad, who think that their sensors are so superior to MAFs. I think they would be better off sticking their map sensors where the sun don't shine rather than running them on their cars since they get off on talking about mafs and their supposed 300hp limits. HAHA! You guys have to remember that an engine isn't really that difficult to understand: airflow and fuel and spark make power. This is the basic concept and one little cylinder shaped sensor isn't going to dictate where that hp limit is as long as it flows enough cfm!

I run SD now and I'm looking foward to tuning it, even though I know it will take 20x's longer than tuning a MAF setup. I wish some of you SD advocates would take off the blinders and open up your eyes as well as your mind to the possibility of new ideas relating to tuning.

I noticed that Traxion has been accepting of Ski's and others results with the MAF as well as some others who once thought that SD was the only way to go for major hp. But what's with you other guys, man? This is our hobby and bashing others is just ridiculous. Why don't you all change your screen names to include "Grumpy" in them. That way us guys who are willing to accept new concepts and learn can ignore your asses.

 

MAF hmm what a concept, I would switch to ford ECM and MAF if I could sort out the distributor part. Those guys use the same stock 5.0 or cobra ECM to run everything from a 289 to a stroker 460 big block without tuning anything but the MAF. I have personally seen 8 second stangs using the stock cobra computer and nothing but MAF tuning that is the draw for me.

 

What you clearly dont understand is how the code operates.

The MAF is maxed at 255 grams.. the short coming is in the code.

While you can pass more than 255 grams thru the MAF, it is no longer an active part of the fueling equation.

But whatever.... ride whos ever band wagon you like.. BW

 

You state you want the thread to continue, and the post something like that second sentence, LOL, OK.

If you care to actually read what was posted it was meter to 300 HP which is vastly different then how you misquote it.

If it takes you 20x times as long, that would be expected when learning a new system. But given some practice the time difference dwindles.

While you accuse others of wearing blinders, some of us have actually spent hours and hours on both systems and were just trying to explain the differences. There's been lots of assumptions, out dated material, and misguotes that some seem to feed on.

And to repeat it again Mark Jackson picked up .2 sec and 3 MPH on his MAFless GN, and is at 9.4s now. Ya, I know it's a turbo, but that's also with unaltered race gas. BTW, there's another 9.8 car that's converting to that MAFless setup, while it's kinda late this season, should be interesting to see what his results are. Both cars are running 83 PPH injectors in a none static mode, and with an actual fuel curve.

And if your running static injectors, the timing against the max advance stop, gutted MAF, at just WOT don't look for much in the swap. You can also run an Alpha-N in that same condition successfully.

And the instant you mention a mechanical Power Adder like T/C or S/C the MAFs take a rear seat. They just can't see the sudden and drastic VE change when boost occurs. Alan Lockheed explains that rather well in some of his writtings, and seminars.

 

Yes, they recalibrate the MAF so they have better RESOLUTION so that they don't peg the calibration. In that recalibrating they get the resolution to accurately meter the fuel in response to the higher HP. But, that's not the way the 3rd Gen MAF works.

While you can recal a Ford MAF to work with bigger injectors at a higher HP level, lots of guys redo the transfer table to get the calibration ALOT closer.

Not to mention a few Mustangs that were running 749s behind the EEC's. ie it all looked stock, but there was a GM ECM running the show. Yep, a racer's never told a lie.

 

The only reason I even decided to say what I said and spew a little venom is one, because I've read all the DIY threads where the MAF (vette) guys were accused of being liers and pretty much cursed for saying they're running 11 sec times with not much tuning done to their MAF computers and two, because I'd like to think that have a somewhat decent sense of humor.

Grumpy, I see where your coming from, and I damn sure know that I don't know jack about the 730 code. So I won't go there, I just know what I've seen w/ MAF setups. They don't take much to get running good times.

I do think that B4Ctom obviously knows he will make a lot more power once he tunes his setup. He might be just trying to make people look silly by saying that there's something wrong w/ his system right now. That's why I don't know what to think. There was a guy who ended up gaining 100rwhp after tuning his SD system, which kind of makes me laugh, cause their ain't no MAF system that is going to need that much band-aiding to make max hp. That's my main complaint about SD, it's too damn picky, especially if you add a big cam.

 

Camaro Joe. What do you consider a big cam? At what point does SD needing tuning? Thanks.

 

Camarojoe,

your lining your self up for a snake pit of attacks....

Today at the track. That is the long straight black thing that returns ETs/MPHs for those of you that don't know Anyways.

Yeah I saw a perfect example of a MAF taking the back seat to a SC setup. To the tune of being introduced to a guy that ran 8.7s in a 4.6L mustang. And it had a MAF meter. Hmmmm. I would take the backseat to that car's ride anytime! And I (1) Hate mustangs, and (2) Don't care for power adders. But as they say we all have our break points.

As for the meter to 300 Rwhp.....sorry I read all the posts I'm sure back at least a few years and in the original context they were written, that wasn't the intent they were scribed. But its your story so tell it the way you want it, however I think it would be easier to say I was "mistaken" and leave it at that. Sorta like it would have been easier for clinton to say, yeah I "screwed" up, and take the ammo away. But I suppose we all have our pride.

 

hmm, uh you cant compare ford MAF to GM, as those guys said after the 255 limit a GM MAF is just a little piece of black pipe with some crap in the way. It looks like you have overcome it for the most part.

 

well the fact that i atually know a few of the Electrical engineers that worked on the 86-93 mustang program let me fill you in.they actually programed that ECM to be lied to with bigger MAFs etc etc etc. there also alot of trouble with the Ford mafs in general. dont get me started i worked tech and tunning at a company that made replacment mafs for ford. anyways its a dead horse. MAF is fine if you wanna get close hell if you run N/A maf is fine. the issue come into pegging the sensor. even poorted with no screens etc the stock meter pegs at 5volts at roughly 680cfm. i dont care what the total flow is. im only interested in what the top calibration is. im working on getting a maf for you guy but **** with all the infighting why bother.

as for S/D cars turning up big power during tunning. oh yeah. the dyno jet measure drum accerleration. if the car isnt accelerating the drum well due to poor tuning then its gonna come up super short on power. go find a mustang dyno thats got an eddy current load and start getting pulled there.

 

Dude - you need to step back and RELAX. When I say ASSume I am referring to myself .... NOT the person who I am talking to. So - when it comes down to it - YOU threw the first shot here because you assumed that my ASSume referred to you as the buttocks when, in fact, I was referring to myself. It's quite 'right there' if you understand the definition of assume. If I assume then it's all about my intelligence ... not yours -- Hence the reason I was calling myself an ***. I call myself an *** and I am the punk? Step back chief. You threw the first punch on this one because you didn't take the time to figure out what I was saying and why. Learn how to relax and stop assuming the worst. Geez. Have a bad day or something? People are so willing these days to immediately assume the worst and puff their chests out like big boys when in most cases they should have a beer and a good laugh ... especially in this case.

Tim

 

Well, actually, yes - yes you are. I called myself an *** and then you assumed wrongly, insulted me, and then threatened me. You're in the bad light on this one. No doubt about it.

Tim

 

Blah Blah Blah

Lets stop wasting the server, and put Tom's issue back on the table.

Peace dude!

 

Has anyone looked into how the extender chip and retro maf work on the 3.8 turbo. I know it's a different ECM and I couldn't tell you squat about the code. But with that program it splits the value the maf reads in turn sending that voltage back to the ecm. So 255 grm/sec would be read by the ecm as 127 grms/sec give or take. If anyone is into the 3.8 as well as prom burning it might be a place to look at. There are many cars out there that will not max the 512 grm/sec capability built into this particular setup. Just throwing something else out there as far as maf setups

 

Let's see.
MOTEC
is MAP

FAST
is MAP

Holley
is MAP

Haltech
is MAP

Bosch Racing as in the newest GM C5 race car program
is MAP

Edelbrock
is MAP

OK, just glad to see all these guys have it wrong.

 

You forgot Accel DFI

 

LOL! Ominous 87 is a TOOL!!

 

What do I considera big cam?? Well about 280-300 dur. at .050" of lift, or whatever NASCARs run. What's a big cam for the street? For a 350 about 230-240deg of int. dur. For a 383-400 about 240-250deg's of int. dur. After my experiences I wouldn't run anything less personally, which means your intake and heads better flow!

I think a SD needs to be tuned whenever you add a cam that's bigger than stock, but you'd have to ask the "Big Dogs", ruff ruff. I know Traxion is one of the foremost experts and has written several tuning articles so check those out first. Grumpy also is quite knowledgable, but as his name probably implies, he's usually grumpy.

 

What is your issue? Coming out of left field with your little comments, like you have a bone to pick.

Did you miss your sewing circle this weekend? Maybe not enough milk from your mommys nipple lately.

Whatever your deal is, it smells like your just out to cause problems.

Get lost pal, I am sure nobody will miss you.

 

OK, it should be:

MOTEC
is MAP

FAST
is MAP

Holley
is MAP

Haltech
is MAP

Bosch Racing as in the newest GM C5 race car program
is MAP

Edelbrock
is MAP

ACCEL DFI
is MAP

SDI
is MAP

Emerald
is MAP

MEGASQUIRT
is MAP

Marelli
is MAP

DELCO Racing
is MAP

Merccruiser
is MAP

 

dont troll my thread



Dont forget that one the ricers use, what the heck is it called?

 

Wow, I go away for a couple of days and it looks like someone got on a shortbus and gave a bunch of the riders a laptop and wirless card…

Like other’s have already said and I originally said, the meter only measures so much air, which typically amounts to about 300 hp. Yea, you can fool it into thinking all sorts of things, but no matter what it still has that limitation WRT to the amount of air it can measure. And yes, you can make more then 300hp with a MAF ecm, but you’re not doing it by accurately metering the airflow but guessing what it will be at WOT, with no reliable sensor input.

Yes, SD is a PITA to get right compared to MAF, because you are not directly measuring airflow, but you have to figure out what the sensor inputs combine to tell you. And yes, a MAF setup is more sensitive and tolerant of small changes, as long as you stay in the range that the MAF will measure.

Well, I doubt that you will find it by changing your fuel delivery, but it is possible that you find a lot more power if you are currently detonation limited (as unlikely as that is with a relatively large cam and low compression)…

if I do, do I get to learn as much as he knows about programming GM ecms? WRT to the rest of what you wrote… Well, see my first sentence.

OK, since you appear to know things that a lot of very knowledgable people don’t, maybe you can enlighten us. How are you getting a 3rd gen style MAF to give you accurate air flow numbers in excess of what it was designed to do???

I can think of a way of doing it (cutting out the sensor section and installing it in a much bigger housing and then adjusting your tables for the larger airflow the maf #’s represent), but I don’t hear/see anyone actually doing that.

I’m assuming that you’re talking about AEM?

BTW, I believe that AEM and Motec will take an input from a MAF, though I don’t know that I’ve ever seen them used that way.

 

I have been through this a million times.

(1) But it boils down to the fact with a more powerful motor 350rw+ you are not cruising the streets at anywhere near 255+ g/sec or your going 100+ MPH, in which case your in PE mode anyways and just running a little rich. See graphs above.....you loosing 10 hp or 10ft/lbs, big deal Do you think your really going to notice that or miss that little bit?

(2) When you do go WOT, you just adjust the WOT % change to A/F vs RPM to aquire the desired A/F ratio that you want to run your car at.

Why do people make it any harder or more complicated than that? Some say there are not corrections for air temp, etc. OK. Then let me throw out these for you. Last weekend Corky and I races our cars in 600' DAs his best was a 10.95 on a 1.45 60' time, and mine a 11.11 on a 1.51 60' time. This weekend we ran in 2600-3000 foot DAs, here are the results. No changes made to either car except I changed and cut back my plugs.

Corkys Runs:

60 1.487
330 4.457
660 6.991
mph 97.91
1000 9.211
1320 11.074
mph 122.81

60 1.485
330 4.449
660 6.979
mph 98.19
1000 9.190
1320 11.042
mph 123.64

60 1.483
330 4.432
660 6.971
mph 98.32
1000 9.179
1320 11.029
mph 123.83

My runs:

RT .587
60 1.528
330 4.552
1/8 7.091
mph 96.15
1000 9.317
1/4 11.199 (not bad for ~2800' DA)
mph 119.87 (lower than last weeks 121-122

RT .535
60 1.517
330 4.543
1/8 7.088
mph 95.47
1000 9.317
1/4 11.195
mph 121.80(MPH is back using the same lane! WTF!

RUN3
RT .580
60 1.526
330 4.559
1/8 7.104
mph 95.81
1000 9.333
1/4 11.213 (tried not locking up my converter)
mph 121.73

Second, one at first glance would say, yeah you slowed down though. But did I. Obviously the hook was not great, but nearly up to par. Lets break the slips down in more detail:

RUN_________60'=>1/8__________1/8=>1/4

1___________5.563______________ 4.108
2___________5.571______________ 4.107
3___________5.578______________ 4.109


Ok, now with that shown, how do you explain the near dead consistancy in a DA fluctating between 2600-3000 DA all day long?

Comparing to last weeks obvious better weather, the 60-1/8-1/4 are all within a few hundreds.

But what do we know? MAF that are obviouisly being maxed way past 255 g/sec, can't adjust for air temps etc right? Give me a break.

I am no longer going to stop anyone from converting over to SD. I can't wait till Corky and I are the only ones running MAF. At about 2-3 sec quicker than everyone else.

Just a little preview: Next year: MAF at 10.5 sec and less from both our cars. No power adders, nothing but motor.

For those that use the aftermarket tuning devices as proof of their superiority, do you think that cost has anything to do with it? YEAH! At an already $3k+, every penny saved make a sale easier. Along those same lines, why would GM go back to MAF as the primary system on thier cars, with SD the backup? As we all know how cut-throat they are with costs. If they thought that SD was better, believe me they would not be slapping the expensive MAF units on every car. And if gas milage was able to be better had with SD, with all the cutbacks on different fleets of vehicles they must meet, believe me they would have SD on every car. But they don't any why? Because MAF is much more friendly and less complaints come back to them that cost them millions of dollars more. SD is only on the cars to satisfy the EPAs ruling of a backup system, otherwise it would be forgotten about as far as they are concerned.

Oh yeah how is this for gas milage, on a MAF equipped car. obviously maxing out the sensor. 22MPG Corky got on this 406 CI motor going from Pittsburgh to Carlisle this year!! Do you think he was messing around on the cruise out with a few other vettes beside him on the interstate? Yeah I think there might have been some playing around, and still maintained a great gas milage.

But as the one guy that came up to corky and I at the last vette challenge said, " Ahhhh you guys are "old school" with your MAF and SRs". As luck would have it, corky drew him in the next time trials. What do you think he was thinking when he saw Corky rip off a 11.0x@123 to his 12.xx@114 with a SD/383/miniram motor

I could hardly concentrate on the burnout I was trying to do, after seeing that floggin. I like old school.

 

Alright, I see now that I misread your comment, when I decided to refute it, anyhow my bad. But this comment means you either spend too much time trying to make a dumb thing sound funny or you spend too much time playing around w/ the techno geeks and trouble makers at you local high school.

Again....I thought you were saying a MAF sensor couldn't make more than 300 hp, my bad. Maybe I need to cut back on the vicodin.

Gee, sorry for being modest, somebody shoot me!

 

Take it down a notch guys or take it back to the PROM forum. This crap doesnt happen here until a few *ahem* people show up.

Stop with the sarcasm and insults. No one likes it and it adds nothing. Show some restraint and stop acting like 3rd graders.


Thanks
Guido, Power Adder Forum Moderator

 

The 255 gm/sec limit on the 165/MAF setup is not hardwired into the ECM, its programmed that way. Anything that is programmed in can be reprogrammed to whatever the hell you want it to be. The only real limit is how much time you want to spend on reprogramming (way more than I want to spend), and whatever the limit of the MAF itself is in what it can report for airflow.

 

I want my Play-Doh. Gimme gimme gimme.

j/k C-Man. I need a Molly Samich.

Tim

 

Stock Chip MAF car that flies!!! http://vette383.tripod.com/

 

You said you were going to be in the 10's this year?.

 

Which are both instantly satisfied with a MAP system.

 

<b>as for S/D cars turning up big power during tunning. oh yeah. the dyno jet measure drum accerleration. if the car isnt accelerating the drum well due to poor tuning then its gonna come up super short on power.</b>

Now that i think about it, do you think that this was B4Ctom's problem or part of it? just how big of a difference in power will one see with a stock tuned MAP ECM on a high performance motor with all the things a stock tuned MAP ECM doesnt like (big cam low compression large low velocity ports and a foreign intake)
???????

And its strange how this map vs maf thing always seems to show up whenever an EFI car with one or the other (thats all of them... in case you missed it) is having tuning problems.

What i cant figure out is if a motor is tuned with a WB then how can either one of the systems be better than the other for full throttle application? I mean, the whole point of the MAP or MAF is to figure out how much fuel to inject, right? and if the fuel being injected is the same (WB tuned per MAF or MAP), how could one possibly make more power than the other? nonsense, i tell you.

but i can see how a MAF would have an advantage during daily driving situations, low throttle / cruise that is, and this is why i think GM and FORD use MAFs, most of the people that have a car use it to get from point A to point B, not everyone hits the track every other weekend like some of us. but thats just my opinion.

OMG now im drawn into the argument! somone help meee!!! nooo! its not my fault i swear!

 

Well, not instantly... but probably in 1/100 the time.

 

Madmax, OK, I’ll buy that 255gm/sec is a limit imposed by the ecm (don’t have information to confirm or deny that), but if it is, what is the maximum that that maf will meter accurately? I could have sworn that 255 was pretty close to the limit of the reference voltage supplied to the thing.

Only if it’s not tuned right in a specific range there… for that matter, where do you drive where you’re at WOT at a high rpm and you’re not accelerating fairly hard? For most f-bodies/vettes we’d be talking about being topped out at between 150 and 200mph, something that almost none of us have ever done (I’ve been pulled over at 147… saw the radar gun, was in excess of that for 7 miles according to the cop, it was a dumb thing).

Unless you’re planning on running the silver state classic (or whatever they name it that year), you’ll want to tune it for acceleration, not best power in any range.

The fact is that cars run the fastest in an application if they are specifically tuned for the use that you’re giving it at the time. This is the reason that there are dyno queens never quite seem to work right at the track is that dynos typically load the drivetrain less then what a heavy car making a hard pass will.

Quote:

And its strange how this map vs maf thing always seems to show up whenever an EFI car with one or the other (thats all of them... in case you missed it) is having tuning problems.

What i cant figure out is if a motor is tuned with a WB then how can either one of the systems be better than the other for full throttle application? I mean, the whole point of the MAP or MAF is to figure out how much fuel to inject, right? and if the fuel being injected is the same (WB tuned per MAF or MAP), how could one possibly make more power than the other? nonsense, i tell you.

Properly tuned within the range of their sensors, neither has an advantage over the other. MAF has a disadvantage if you exceed the airflow it was designed to meter, MAP has disadvantages if you do anything that limits the granularity of the output of the MAP sensor (very low idle vacuum can make it useless, high boost needing 2/3 bar maps decrease it’s accuracy…)

Quote:

but i can see how a MAF would have an advantage during daily driving situations, low throttle / cruise that is, and this is why i think GM and FORD use MAFs, most of the people that have a car use it to get from point A to point B, not everyone hits the track every other weekend like some of us. but thats just my opinion.

GM and ford went back to maf for emissions reasons. It’s better for adjusting for different weather conditions, engine wear… and maximizing low/part throttle mixtures

 

Did the season end yet? Corky just hit 10.95 last weekend.

And how you making out with hitting 13s from a few years back?

 

Mmmmmmmmmmmmmm

 

Hard to say. The MAF itself will flow about 7-800cfm without screens and fins, or the Wells route. I know the stock Bosch is calibrated within the MAF itself for a certain "airflow"-voltage range, but I also know you can change that. How much is beyond me, I never went that far into it... honestly I dont think its worth the trouble. As for the 255 gm/sec in the ecm, it is a limit imposed by the programming. You could do a search on the prom board and you'll find plently of people to confirm it. Only thing it means in reality is that its no longer providing the actual airflow once you hit that point. Look around enough and you'll find that there are plenty of people showing how little that really matters in real life.

Personally I think the whole carb-MAF-SD argument is childish. You go find yourself a fast SD car that does ok in different situations, and I'll go find a carbed or MAF car to match. Each has their own strengths and failings, you just pick which one suits your needs and your requirements. And since this IS the power adder board... I've picked up a toy myself and I'm going to run it on a MAF setup only because its there. I've sat here and tried to figure out a way to get it to understand the whole picture, and without putting in more effort than I'd want to, there is no way to tell it. It just makes more sense to run SD instead, so eventually thats what I will do... not because its better, but because it more accurately serves my needs.

 

You were the one talking about next year.
What's Corky's car got to do with your claims?

Your the one with the ET obsession.

 

Look Grumpy, I am not going to play your little games. You would think you would have learned from the last scenerio.

But the obsession continues

 

Having actually worked on some turbo carb'd setups, I'll beg to differ with your opinion. There is just no way to get the transistion fueling from N/A to boost correct. Even using a vac secondary carb., and using boost to open it still is extremely crude. Never mind trying to data log and generate any useful tuning data.

In any boosted situation the SD is in fact better.
If someone's just running static injectors and no actual timing curve then SD, MAF, Alpha-N, just all blurs together.

 

I think you misread what I wrote in your edit of my reply. I said (or meant to say) you need to pick the appropriate 'tool' for your needs. I wouldnt run a carb by choice with a turbo either. It'll work just fine on a NA setup though.

 

Can somone tell me if its possible for injectors to go static below a 100% duty cycle?

I have also heard that some injectors just lose control somwhere around 80% is this true?

 

if they go static then why do we tune for PE? ( I dont really know much about it)

Why dont we just tune PE with the AFPR?

 

Sure, most do. I think that bosche’s standard is that they’re good as long as they don’t go static before 75% DC, but they measure it at the equivalent of something like 8K rpm. With injectors where they go static is not really about duty cycle, but how fast you’re expecting them to open and close.

 

Crossfire- good info. I had wondered about that for some time. 80% duty cycle at 4000 RPMs is a very different thing that 80% duty cycle at 8000 RPMs.

Despite the bad behavior in this thread, I STILL learned something.

FYI- Having worked on a few MAF cars (but being no expert by any stretch) I'll jsut make the general observation that WAY TOO MANY PROBLEMS are blamed on maxing out the factory MAF at the 255g/sec limit, or even the actual airflow restriction of the unit itself. Having worked with ported stock units (screens, sinks) you have to make some real power to hit 255. A 400 SBC I built for my brother was pushing around 400 HP on a chassis dyno and was almost (not quite) maxed out jsut shy of redline. The exhaust sniffers on the dyno said we were running about 13:1 A/F and that was using an off-the-shelf TPIS chip (even though everyone said their tuning sucks). Every guy who doesn't make any power over 4000 RPMs instantly thinks that it's gotta be the MAF. Bullsh1t. They can go a lot further than most people think they can. High 11s through a ported stock MAF should be very do-able even by a reasonably experienced weekend warrior.

Blower or Turbo? Yeah, you'll hit the ceiling pretty quick. But for a N/A motor you can build a fairly stout combo without having the MAF hold you back.

And it certainly is much more forgiving of combination changes than SD is without having to reprogram. That MAF meter can cover up for a multitude of sins. It's got a few things going for it, even for high performance use.

 

People dont argue about hitting a performance cieling with a MAF. They do however argue on the lack of ability to manage the fuel deamnd on an engine past a certain point RPM and HP level.

Its pretty simple. Once you exceed the maximum level of metering you are forced to fuel Via PE. Not exactly a something that can be tailored to an engines demand beyond one variable, that being WOT to be safest.

Example:

Say a MAf ran out of resolution on an extreme combo at 50% throttle, BC the engines airflow deamnd exceeds that of the the meters resolution. Its tuff to say that the PE fueling routine will be tailored properly to the other 49% of throttle position until it hits 100% and PE is dialed in properly. Hence the biggest limitation of the MAF.

Max performance is not a week point of the MAF, limited resolution is.

Where a person draws the line is personal choice. I have a MAF car and would like to convert to SD. Its a more defined and contolable way to run an engine.

 

Ominous_87,

Yes you understand exactly what I have been saying about MAF. But let me take it one step further, to show you how little it really matter that your maxing out the MAF.

Given your situation, which is a EXTREME case/combo, but lets use it anyways.

As you said, once you pass 49% throttle you go into "the gray" area. Air flow is maxed and your into limbo land. No arguement there. Happens on my car all the time, well anytime I exceed ~3/4 thottle, which on the street is seldom to never. And in your case with your extreme combo, you would probably never get near 1/2 throttle on the street without blowing the tires off. But lets continue. Ok. Now we are accelerating at a good pace steady applying throttle. At 49% throttle we exceed the MAF resolution, but not its max flowability. What also happens is the car has entered PE mode also at some point. This envoke the ECM to run the PE % change vs RPM etc parameter. This in turn run fuel into the system and causes us to NOT go lean, but rather overly rich. This will happen till you reach WOT and the airflow you have tuned WOT and PE is reached.

So as I have shown above how much doesn that really "hurt" performance? Virtually none. I have shown graphs that show A/F ratios vs power deltas, actually dyno graphs from extreme low 10s to mid 14s with only minimal changes in power. In the neighborhood of only ~10 hp or ft pounds lost. Does that little bit honestly matter? For street driving? Hell a slightly lower than normal tire pressure can cost you that much, or a slight head wind. Its negligible.

Now let me tell you what I see on my car in detail when the above happens with reference to my WB. Under decent acceleration in my car, not breaking the tire loose, and steadily applying the gas to the point of feeling the rear wheel wanting, but not loosing trction, my AFR will be at ~11.9 up to which point I get to WOT, then it will follow my desired setting to a T. It will bounce between my newest settings of 12.8-13.2 AFR.

My educated guess is based on my dyno pulls going from one extreme AFR to another, that I am probably loosing ~5 hp in the above scenerio. And that is probably an overestimate.

Now back to common sense thinking. Sure I am outta resolution, my car is adding more fuel than I truely need, since its in PE mode and airflow is less than WOT from 50% -99% throttle, however a change of 1 AFR unit is not going to stop the performance world from spinning.

Look at the information that is presented here and honestly tell me that is matters.

Keep in mind this example as you said was an EXTREME combo. I consider my setup pretty extreme, yet I only max the MAF at about 3/4 throttle and ~4000 RPM. So I highly doubt there are many other combos here on the board that encounter maxed MAF meter sooner than that. In my case I loose resolution for about 1000 RPM (for 1st and second gear that is about 1-2 secs to rip through that RPM level) and 3 gear I go through the traps at 123 MPH at 4600-4700 RPM, so I doubt very much people are tooling around on the street in 3rd gear at 4800 RPM in a motor that maxes the sensor out.

I am not trying to be a jerk, but when you put everything into common realworld application, you soon, at least I hope see that its really NOT a big deal. Its been blown WAY WAY outta proportion.

Ominous_87, you have the correct scenerio in your head of what is happening, that is what people do not get, and why they do not understand what I have been trying to say. Thanks for listening.

Damon, I agree 100% with what you said! :cheers:

 

While the above post is a very illustrative example for street use or drag racing it is hard to apply the same logic to any type of "course track" racing. With alot of turning, slowing, and speed limitation placed on these cars it is by nature of the sport that these cars will spend the majority of their time with the throtle in the 50%-99% position.

In this case total engine control is very critical for many reasons and the MAF system just plain falls short here. While passing through AFRs of 11ish for very limited time periods on the street or drag strip is fine its not exactly where someone might want their engine to sit for extended periods of time in "course racing", and not to mention the fact that however small it might be fuel would be wasted.

 

Ominous,

Can't agrue that one bit, again it comes back to how many people that here compete in road course events.

Most are in Drag racing or street performance. In which case for Drag racing the entire above scenerio is botched, since you go from near idle throttle position to WOT instantly, In which case your AFR is set to your desired preference.

On the street, most case will never reach the 255+ limit. If they do the losses are minimal.

But for a road type course your absolutely correct. I do however based on the fact the losses are very minimal, still say there is no real advantage. But fuel consumption will be greater, but I don't see a reason to complain about consuption, if your hammering away on your car at any sort of race event, unless MPG means you make it to the next pit stop.

Good discussion. THX