This is an age old debate about "Maxing" out the MAF then having to go into the PE mode.. If you know what you are doing, calibrate the MAF accordingly AND use the PE function there is absolutely nothing wrong with that method, I run a MAF with a a D1 in my LT1. Made 648 RWHP on pump gas with 12lbs & 722 RWHP on the STOCK MAF, A/F was a flat 11.5 right where I commanded it, year later got back on the dyno, Still flat as a board at the same commanded A/F.So do what ever make you feel better. Me I will stay with my method...

 

Your method is fine for a supercharger that never gets the pulley changed. A turbo or one that sees the blower pulleys changed from time to time will require you to retune. You are right though, your method works plenty good enough.

What about where you max it out then, surely there have to be times when you give it gas pretty good but not flat to the floor... takes your maf more rpm to max out and then your pe calcs are way wrong and you run absurdly fat. Just throwing that out there. Obviously the effect on this depends on your exact setup.

Dookies method is as far as i can tell the only real good method for turbo tuning with the factory pcm. Twist a **** to increase boost etc and shes still tuned up for it. or if the wastegate screws up (vac line fails) you at least stand a chance of not fragging it.

 

yes you are correct that if you change pullies then a retune is in order. about the 1/2 throttle part, Not sure why mine did not run fat as said, Maybe because I ran smaller pullies to be at full boost by 6000RPM, it spooled up very fast at even low throttle. maybe the extra forced air was keeping it close...

 

I dont think the issue was with the MAF method not working, but it's purpose is to measure Airflow, since it basically can only measure airflow up to a certain RPM based on your setup then there's no point really in using it since it's now just a restriction. SD works just as good actually better (faster throttle response) than the MAF setup.

I just dont like the MAF since it doesnt work for the whole RPM band, that's really the only reason, that plus the slight hesitation MAF systems give (very slight).

Also just so happens around the same time I was trying to work around the MAF is when i realized I needed to jump right to a 2 bar setup and skip all the nonsense, like WS6T3RROR says it is simply safer to run 2 bar plus you get full timing resolution, not just a flatline.

 

I also ran 2 bar, as far as any hesitation, I had absolutely none, In fact on the dyno and street people were telling me that I had nitrous because they never saw a supercharged car spool up that fast, Of course I had light weight everhthing, I'm sure that helped...

 

Using a MAF? spool up and hesitiation/delay are different, Any MAF system has delay it's how the MAF works, it measures air (measuring wire current) then calculates fuel, there's a delay, not very noticble but it's there. Any SD systems have 0 delay, they just rev.

RPM climbing rate of speed has nothing to do with MAF delay, it's there the instant you blip the throttle with a MAF, also not to be confused with studder, studder is an actual problem, MAF delay is the negative side effect of measuring air entering an engine.

MAF delay can be compared to Drive by wire, most drive by wire has huge delay from the moment you hit the throttle until motor actually starts to rev, MAF is almost not noticble compared to drive by wire.

 

Spool up, hesitation, delay what ever you call it so be it, all I can tell you is with my setup the minute I hit the throttle, watching the A/F graph immediately dropped down to the commanded A/F. Now if you are talking about the time from when I hit the throttle to the actual A/F, of course there was a delay....a milisecond?? Like I said tune to what you like, I will stick to mine, Dirveability was perfect, no bucking, no studder, drove like stock until you hammered it down. I have since pulled the supercharger and going turbo, I might try the SD thing to see if there is really a difference, Good luck to you..

 

Its going to be a little different for you when boost is no longer tied directly to rpms as it is with the supercharger which is mechanically driven. That and the fact that boost is really easily adjusted with the turbo will make the way you do it now inadaquite.

 

X2... I have been running a MAF tune with the PE vs Rpm adjusted for 3 yrs now. I have a wideband guage mounted in the car so I monitor the fuel all the time when doing spirited driving around town or at the track. My run of the mill MAF tune commands the correct AF ratio at ALL RPMs, ALL throttle positions, and in ALL weather conditions.

All this talk about maxing the MAF is really just cyberhogwash. It is easily compensated for with the PE vs RPM tables. I think GM knows what they are doing when they decided to spend the extra money to put MAF's on virtually all of their cars.

 

Your gonna hate this response, but MAF's are serisouly only for MASS PRODUCED cars since they allow for more variation in tuning/engine variance from factory (read up on it -example from wikipedia at the bottom).

MAF's have lag, any knowledgeable person knows it, whoever says they dont either doesnt have it hooked up or they dont know what lag is.

1) "All this talk about maxing the MAF is really just cyberhogwash": OK, then why doesnt GM make cars that max the MAF from the factory and rely only on PE vs RPM? , also the MAF in systems with large amounts of Reversion, can be troublesome to calibrate.


2) "I think GM knows what they are doing when they decided to spend the extra money to put MAF's on virtually all of their cars." Again, GM doesnt put MAF on all cars, the only reason they do is cause all engines have variability and one set of SD tuning wont be optimal for all engines, and by the way the ones they do put them on READ the entire airflow range. , again the MAF in systems with large amounts of Reversion, can be troublesome to calibrate.


http://en.wikipedia.org/wiki/MAFless_Tuning
Advantages
By changing the engine from MAF mode to MAFless/MAP mode, vehicle modifiers claim two advantages:

The MAF may pose a physical restriction across the vehicle's intake tract, thereby reducing airflow into the engine. By removing the MAF this restriction is eliminated, potentially improving engine performance.
By moving the airflow measurement sensor from the intake plumbing to a point closer to the cylinders, the time lag from air moving past the sensor to reaching the cylinder can be reduced, thereby improving throttle response.

Disadvantages
A potential disadvantage of converting an engine from MAF to MAFless mode is that where the MAP sensor is used to measure airflow, the corresponding fuel calculations must be performed by the computer based on tables of information programmed by the engine tuner. If other parts of the engine are subsequently modified with an effect on airflow through the engine, these fuel tables must be adjusted to match the revised engine hardware. As airflow is measured from the MAP sensor so the turbocharger variations will affect the fuel flow measurement resulting in higher fuel flow or lower fuel flow, and hence smoke limitation. Without MAF, monitoring of the airflow is very tough, and so the chances on reproducibility of the desired performance in the field is very less. EGR with the feedback system and exhaust sensors are necessary to lower the chances of engine to engine variation of performance. By contrast, when operating in MAF mode the computer can automatically adjust its fuel delivery based on the airflow data generated by the MAF, even if other engine hardware is changed.

Another small disadvantage is as the engine wears, the mean vacuum is decreased. This 'fools' the MAP sensor into overfuelling. This is only a problem on very high mileage engines.

Applications
MAFless tuning is a popular modification in Australia for Holden vehicles powered by the General Motors LS1 Gen III 5.7 V8 engine. The genesis for MAFless tuning of the LS1 in Australia was the HSV GTS version of the Holden Commodore, which was factory fitted with a Callaway-developed C4B version of that engine running in MAFless mode. Rated at 300 kW, the C4B was the most powerful factory LS1 sold in Australia and created substantial credibility for MAFless tuning of LS1 V8s. Within days of the HSV GTS's release the CSV Veloce was on the Australian market with a 330 kW LS1 incorporating a MAFless configuration, and taking Australian motoring performance to a new level.

 

[QUOTE=dookie454;5809958]

MAF's have lag, any knowledgeable person knows it, whoever says they dont either doesnt have it hooked up or they dont know what lag is.

A milisecond of lag?? Who cares

1) OK, then why doesnt GM make cars that max the MAF from the factory and rely only on PE vs RPM? ,

Just another tuning aid, why then do they have IAC, IAC park, Throttle cracker, VE ect, ect. Then why do you have to adjust VE? Maxing out the IFR tables??


The MAF MAY pose a physical restriction across the vehicle's intake tract,

Does not say IS

Disadvantages
A potential disadvantage of converting an engine from MAF to MAFless mode is that where the MAP sensor is used to measure airflow,
Another small disadvantage is as the engine wears, the mean vacuum is decreased. This 'fools' the MAP sensor into overfuelling.

Your own statement.

Again it is great for people to try something and find out it works for them, but you dont have to tell others YOU ARE WRONG at what you are doing, I have none of the so called lag, lean spikes, rich tip in, I even pulled the super charger and ran with the 85lb injectors N/A, still smooth driving, perfect A/F.If
your method works for you fine..Others, their method works for them fine also. But every parameter could be dissected and say why..When people tell me they do something a different way and it works for them I say great, not, you dont know what you are doing and I am obi one canobi

 

Everybody needs to calm down just a little, keep the thread informative not some arguement about my dad can beat up your dad, both setups can and do work one is just more robust. Lets leave it at that.

 

Agreed, let the info flow and each do whatever they feel comfortable with. Oh and my dad can beat up you dad..LOL

 

I'm very afraid to comment. Thanks for the different approach for FI tune. Notes taken.

 

I agree, just posting facts. Some people take part of the fact and make it more than it really is (like me saying someone is wrong for wanting to use a MAF?).

I never said anybody "wrong" for using MAF, just they are there from factory mainly to compensate for each motor's variance from the factory, and yes it takes 100,000+ miles for engine wear to stack up enough for SD tables to need to be adjusted.

So, back to the point about why you wouldnt want to use a MAF, if it maxes out in your RPM range then you dont want to use it since SD is tuned just as easy or better (from the people who actually have used SD mode - including aftermarket systems).

My Saturn SL1 has 210,000 miles, no MAF, runs great. Point made. MAF would not do anything except create a little delay, not noticable to most people. What they did to ensure MAF-less was ok is better tune the SD tables and ensure the engine tolerances more closely match other SL1's, in the end it's cheaper to run MAF's since you can spend less time making sure all your motors are exactly the same.

That was alot more work getting my point across than it should have been.

Oh, my dads a wimp, he hates cars too.

and just to answer: why then do they have IAC, IAC park, Throttle cracker, VE ect, ect. Then why do you have to adjust VE? Maxing out the IFR tables??
IAC is for exactly that, to control idle air into each intake port (and not to use the throttle blades since that causes flow problems at idle);
IAC Park is so the PCM can slam the IAC back to "home" and not worry about being to low or high;
Throttle cracker: ?? unknown tables to me
Why Adjust VE? That tells PCM exactly how much fuel the engine needs at any given load vs RPM. By using VE tables you DO NOT need any other tables for fuel except COOLANT TEMP corrections, like a choke on a carb. this means PE vs RPM can and should be at 0 for everything.
IFR Tables: ?? unknown tables to me