WAHUSKER

iTrader: (4)

I saw an article in this months Hi Perf Pontiac about a place that calibrates 85mm MAFs for cars like mine. I talked to a tech today & I am ordering one & having them tweak my tune to match. It's actually pretty reasonanble.

The tech told me about some pretty impressive numbers from cars they've worked on. Like over 700rwhp from a car like mine. They have a Lightning that runs 10.40s. He has an LT1 that runs 9.60s on a 250 shot. Etc etc.

I will let you all know how it turns out. I might move up the list yet.

John B

iTrader: (10)

85mm??? I just bought a 100mm unit from LPE for my LS7. You should get this one too since it is made for blower application!

CHarris

iTrader: (5)

Did they explain how they tune the MAF? I've never understood the concept when the table is in the pcm program. I guess I just don't get it but I sure hear a lot about special MAF calibrations. What else did they tell you about it?

jimbob

iTrader: (4)

Just stealing your money...period.....Special calibration ...By the way your maf has the resister mod from SLP. Your tables in the computer are still only upto 12000 hz...If they can modify the tables longer then yes it will read more before maxing out.....Have not seen anyone that can do it yet...

Robert56

iTrader: (2)

Doesn't the Z06 go higher than 12000 hz, to 13500 I think IIRC? I will look later.
Robert

jimbob

iTrader: (4)

The only way to make a maf act higher is to trick it into not telling the right freq vs airflow (in order to fit in to a 12khz table). The problem comes from trying to squeeze these tables into a 12Khz table. On a FI, your shooting yourself in the foot. You would have to add BIG PE in the area thats extended/tricked. So you can add big PE in one extended area, or normal PE across the scale for a correct reading MAF. The idea is to not have a MAF max out, which on "Big FI" it still is going to happen...So, what's the point?... Just add enough PE after the maf maxes out to obtain your desired AFR....Now on a "NA" engine nearing it's max freg then I can see doing it. I would go with the LPE 100mm MAF for the lesser restriction for the FI then some tricked out maf that really going to cause fueling issues with his combo. If I were designing a MAF to fit into the 12khz I would just cut the whole freq by 25% then change the injector constant/IFR table to compensate. Someone would only need design a plug in circuit between the maf and the maf plug. Cough...hmmm MAF translater (although I don't believe it goes more than 10% change...but you get the idea)... Oops, I just gave a way the answer....

WAHUSKER

iTrader: (4)

Yes you did Jim....BAD BOY!

The limitation is the 12kHz of the MAF and the 512g/sec in the main PCM program. But more or less the guy told me they scale the MAF & PE tables etc according to your injector & motor size to change when / where your MAF maxes out. Actually they make it so it doesn't anymore. While I agree that you should be able to tweak it yourself, I just haven't been able to get it perfect. And I think I'm leaving power on the table.

With Ellis' help my tune is close, but when the MAF maxes out @ 4500 rpm the car starts to lean out, and no matter what I try it isn't right. It doesn't seem to add more fuel after it quits registering an increase in air. So I'm willing to try a new approach. I was going to install the 85mm SLP MAF I have & play with it, but these guys have tuned many FI cars & seem to know what they are doing.

That 100mm LPE MAF sounds like an intersting alternative John. Thanks, I'll look into it.

There is always the speed density approach, but IMO all you are doing is removing the best sensor you have from your system. Plus you have to get a 2 bar MAP & software and then the tune would still be limited to how accurate the O2s are. And then for driveability I'd plug it back in anyway, so I'm just not convinced SD is the answer.

Anyway, I'm not trying to offend anyone, I try just to share what I find. Since I'm not going to hack my car up to make it lighter, the only way for me to give Ellis & Ryan some competition is to find more power. Not to mention I GOTTA stay in front of those juiced-up plastic toys! And that Lil Frig is going down!!!

MrDude_1

iTrader: (4)

if its the "best sensor" or not, is debatable.

but its pure scientific fact that its the least accurate.
the thermocouples and pressure transducers (temp sensors and MAP sensor) are ALOT more accurate at measuring what they measure...


but anyway, im NOT trying to turn this into a MAF vs SD debate, since they never go anywhere and just clutter the board up.

that said, do think you have some misunderstandings of both the MAF and SD systems that you'll want to clear up before spending money further, one way or the other.

TwoFast4Lv

iTrader: (8)

I will simply state,As I have been playing with hacked up MAFs and tables for a few years now, that the only real way to get around the issue would be a complete re-write of the code as some have done on the LT1s.

Most of the LSx PCM is writen around the MAF with a MAP back up. WHy not use both as inteneded I have yet to get in a LSx SD car that drives as well as a MAF car. . . and I have driven some tuned by some of the best out there. SD tuning is great for racing there is no dought. Problem is our weather swings from Extreme to the other in a matter of days at times With all the offset Tables It is a truely daunting task to get it where you need to go.

Now your 91 is SD from the Factory so many of those tables are setup great to begin with. On any thing newer they are set up as back up tables and do not get the refinement needed.

I feel a good tune involves covering both sides of the coin here. SD and MAF tuning The biggest problem is the Stock code was never writen for Boost. This makes it a Royal PITA to get working correctly and there is ALWAYS a comprimise

At least on Your 91 you can use a hacked GN code that under stands boost to get by

Robert56

iTrader: (2)

Nope, I guess the 85mm z06 maf goes only to 12000hz also. When us nitrous guys max out the maf and it goes rich, we just up the nitrous jet until the desired a/f is reached, hehehe. I know it's different with boost cars, but you guys seem to have a handle on it. I agree with Ellis on SD tuning around here, to many variations day to day/month to month in weather. Now maybe if you had a SD just for the track? still you would be fine tuning it all the time I would think?
John, how much are the 100mm MAF's going for?
Robert

Edit: Mark, those plastic juiced up cars are a coming, really though, we have a way's to go before we get to the top 4 guys currently, but next year...

WAHUSKER

iTrader: (4)

I spent a day working on SD, started to make some real progress and then gave up when my O2s started to foul out. As for misunderstandings, I have plenty. If I knew what the answer was, I wouldn't need to buy anything, I'd fix it myself.

As I see it there are 2 solutions that people are using, SD or massaging the MAF tables to fool the PCM. IMO neither is a complete solution, both ways have holes in them. But as I have said in the past, I think if you can tune your car properly WITH a MAF you are better off.

Looking at LPE site, they offer a very similar product (a new larger MAF for $300). They offer tuning directions and wire harnesses too. A 100mm MAF + tuning directions vs an 85mm with a tune. Hmmmm, decisions decisions.

http://www.lingenfelter.com/Merchant...Category_Code=

00Vette

iTrader: (4)

You gonna get this done before the 20th and/or 21st?

WAHUSKER

iTrader: (4)

Doesn't matter, since I can't make it this weekend. Maybe by next weekned.

Poik

Did Ryan K have big problems with SD on his Camaro?

TwoFast4Lv

iTrader: (8)

Get the 100MM and lets go for the full boat

WAHUSKER

iTrader: (4)

That was my first thought too. But then I figured I'd want a 90mm LSX intake & TB to match it. And then I'd need some AFR 225s. And then you'd talk me into an F3R. And then Jimbob would be designing me a new bump stick. And then.....

Thinking an 85mm flows 1100-1200 cfm, and the guys at Mass Air Systems have worked out the tune for a car like mine, and my goal is NOT to run low-mid 9s I'll probably go with theirs.

tjwong

Even if a replacement MAF reads past 12k Hz you wouldn't be able to use it unless you are able to make changes to the PCM hard code that would enable it to read past that point. Use the LPE 100mm sensor, it will work fine for you application. And as for the temp and MAP sensors being highly accurate. I can tell you that these sensors are not as accurate as you may think. I have tested these with precision pressure calibration instruments and they are not dead nuts on. They are fairly close, but close enough for engine controls. You can take two different ECT sensors, place them both in the same temperature calibration bath and both will read different. Once again they will be close at plus or minus 10 degrees. MAP sensors I have seen to be as far off as 0.5 PSI!!

WAHUSKER

iTrader: (4)

Thanks Tom....once again you & Ellis are in agreement. Guess I better change my plan.

MrDude_1

iTrader: (4)

well, my car doesnt seem to have too much of a problem with running SD.. its been doing it for almost a year now...

and as far as my car knows, its a 2002 fbody... im using the LS1 PCM, harness, ect.... its the same.
my friend jason is also running his auto the same way without issue (im a M6).

yes, we both spent alot of time on the tune... but in the end, we have the same drivability, same mpg.. ect..

i agree that diffrent code is needed to be ideal... id LOVE a nice custom OS that did the fueling like i want with a nice high resolution SD table... and i suppose as long as the code is being done, you could make a larger MAF limit as well...if you want to.

personally, i dont know why someone who DOES THE TUNING THEMSELVES would not want to run in SD all the time.... but i can understand for 99% of the people out there, that they want to just drive.. most people dont understand or even want to understand PCM tuning.

anyhoo, im going off topic and steering the thread the wrong direction with that..

point is.. you have a MAF limit in the code... you need to work around it somehow... either replace the code, hardware translator with a rescaled tune, up the PE so it dumps more fuel.. ect...

WAHUSKER

iTrader: (4)

I appreciate everyones comments, and welcome all opinions. I really do. Because like I said, I have tried SD & didn't have much success. So this bigger MAF with some tweaking sounds like a valid alternative to me.

When you stop & think about it, what you have is more air going into the engine than your computer knows what to do with. So the solutions is to make an adjustment. Smart people at LPE use a bigger MAF with tweaked files. Lots of guys including some really smart people at HP Tuner have had success by disconnecting the sensor & tweaking ****.

The bottom line is you gotta tweak a bunch of parameters. And I openly confess to not knowing what all of them are. Which is why the MAF option is appealing to me. They might point me in the right direction. And after the year of mods I've made, what's another $300. Especially if it gets me past where I am now.....

And like Da Grump says, after you listen to all the experts, it comes down to you just gotta try ****. So Ellis, after I buy the 100mm MAF, you & me need to pay a visit to TJs shop & do some serious tuning. I'll even spring for a trip to Hooters afterwards.