MAF or MAFLESS TUNE

[JR-CRUZN-C5]

You know about two months ago I decided to do something my tuner has been "bugging" me about for quite a while - Run with NO AIR FILTER to lessen the work load on the blower in 3rd gear. (F1R with a 3.70 pulley)

I went on numerous forums including this one to see if anyone would know what the result of removing the air filter might be. == NO HELP!

In order to do it I had to put new plugs in, make a run, pull the plugs at the end of the track to read them, record each run reading the GM voltage on the 02's AND compare the readings to my FAST wide band. Make adjustments and do it all over .

The only problem area turned out to be the RPM range 800 - 2,000, it went dead lean even before the car moved off the line (My launch RPM was 1100). The PCM seemed to pick up and accomodate the increased air flow from 2,000 RPM out to 6800.

The results were amazing - 1 to 1.5 tenths quicker, shift points changed as the car drove deeper into the convertor, boost went up by 2 -3 which at 6+ HP per lb of boost is substantial. Now you guys know what I know!

All that to just run with no air filter - The tune in my car is the result of HUNDREDS of passes down the 1/4 mile with trial and error on tons of things. Its not likely I will be going to MAFless any time soon. There are VERY FEW C5Street Vettes running low 9's consistantly. I'll continue to fine tune my MAF tuneup until there is a CLEAR, TANGIBLE reason to make the change. I don't see any of the top shops putting out a vette with my IRS Vette Setup and a MAFless tuneup that runs at my level 100 runs each year!!!!!!!!!!!!!!!!

JR

[Harrismarine]

Hi Mike,

I'm going to take a guess that this is to do with your 6lt project. From memory you were going with the E38 controller so I'll tailor some info on that.

With the LS1 PCM, the majority of tuners would go with a MAF-less tune, but with the late model E38, there is no clear favorite. Some of the reasons for this ( in my opinion ) are...

• Tuning knowledge.
• Larger stock MAF size.
• Speed of the E38 PCM.
• Additional tables in the E38 PCM.

A good example of the differences in capability of the stock E38 controller is the fact that EFILive sees no compelling reason to offer full Custom Operating Systems for the E38. The usual response to requests for an E38 COS is "It's already in the stock calibration".

So I guess I should list some advantages of each type of tune.

MAF:

• The MAF will compensate for air density / IAT automatically.
• The E38 uses the MAF signal to operate certain tables directly.
• If you have a street car and EPA rules require the MAF to be "in place and operational", then there is less chance of trouble.
• The MAF can be tuned just like the VE table, so accurate fueling can be achieved.

MAFless:

• The MAF can be a restriction in the intake path and reduce max airflow at WOT. removing it also removes this restriction.
• There is no "delay" in air flow calculations from the MAF. Because the MAF is usually some distance from the TB, it takes time for air flow changes to reach it and then for the MAF sensors to react.
• For larger CAMs, if the MAF is too close to the TB, a "reversion" condition can occur where the airflow over the MAF sensors becomes unstable and the MAF reports incorrect data.

There are probably lots more, but those would be a few common traits of the two tunes.

Of the two, there is no doubt that a MAF tune is quicker and easier to set up, especially for a daily driver and more so if the car is an auto. One of the areas that seems to rely heavily on the MAF is the fuel dynamics. In a manual car you can get lean spikes on gear changes unless you do a lot of work when running MAFless. In the end though, I think MAF or MAFless will be a personal choice. To help that choice along, I'd think about the following...

[indent]

1. What is the vehicle going to be used for?
   
   
   

   • Daily driver, lean toward MAF
   • Weekend drag car, lean toward MAFless
   • Bit of both.... either.
2. How will the vehicle be used?
   
   
   

   • Lots of mid throttle work, gear changes, lean toward MAF.
   • Only really idle or WOT, MAFless.
   • Bit of both.... either.
3. What are your tuning skills like?
   
   
   

   • Bit of a beginner and not too sure, leave the MAF.
   • Tuning god and can convert lambda to AFR for any given fuel type in your head.... MAFless
   • Somewhere in between and want to learn, either.

Again from memory, I think you were setting up a boat, so it will probably respond pretty well to a MAFless setup, given you won't be on and off the throttle all the time ( unless we are talking jet boat racing ). I think the main reason for MAFless in drag racing, is the fact that the MAF can take longer to respond to changes, and when all the action can be over in less than 10 seconds, every millisecond counts. If on the other hand the action lasts for 10 minutes, the MAF response may be made up for in other areas ( like dynamics ) that may make it a better option.

Simon.

Hi Simon, Its not to do with anything except we had a motor arrive from the states that a mate sourced for us to put into his jet boat. It arrived with a MAF sensor. It has been dyno tuned and came compleate with computer and tune, but no Knock sensors or wireing for them.
I dont see the need for the MAF and 99% of all my tuning is Maffless. But obviously some believe that they have some merit.....so im interested in opinions of other tuners. and it looks like it will be a good debate

[Highlander]

With the E38 I had a customer and we were dead on set doing a mafless tune. Having done countless with the ls1, i just thought.. this is going to be easy... Well... not quite...

My main issue was a retard going on out of the blue, and the car didn't make as much boost as it should.. Why? I have no idea. The other problem was that it was PEGGING the g/cyl to 1.4 and thus getting to the end of the table and then a linear table for timing could only be achieved. I was not "pegging" the maf although I was close, but pegging the timing table to the end meant that i had less conditions for timing if things got in the too much power happy side. Since we have no "retard" per psi, the more psi you make the more the maf will "read" and the more to the right and thus a lower timing could be achieved /psi boost.

[TuneMaster]

Tunemaster: When tuning the E38, it's not really fair to say that doing a MAF tune is "lazy". As I've mentioned, it's not the same as running a full COS in the LS1 PCM and there is a huge amount of work getting things acceptable for a daily driver when running MAFless, more so for the M6 guys. Another thing to remember is that a "proper" MAF tune takes more work than a MAFless tune as you should fist perform a MAFless tune, then re-enable the MAF to tune it.

Simon.

I agree to a certain point, but I have corrected many tunes from others where their idea of a tune is to slightly modify the VE, MAF and PE to achieve a decent A/F ratio. The end result is MAF and PE numbers are all over the place. It takes less time to dial in VE on the dyno and then set PE accordinglly, hence no need for MAF!
E38's are difficult MAFLESS but come into play when the engine is Cammed up. We all spend Hours and Hours tuning these suckers and I've seen some shockers. There are heaps more tables that need tweaking to get a good result but thats why we use EFI Live.
At the end of the day its all up to the individual but for me I tend to favour MAFLESS depending on setup.

[swingtan]

You're not wrong there.... I've seen a few shockers as well. A shop that ended up setting the low spark table higher than the high table comes to mind and when questioned about this said "that's how you get power out of these things.... "

I'm currently running a full OL SD tune in mine and it's running very well. For a manual, I do think it's a fair achievement given the vast majority of the work has not been on the dyno. When I'm really happy with everything at street speeds, I'll put it on the dyno to fine tune the top end WOT areas. For now though, on the street it's an extremely well behaved car.

I've been tuning the E38 for a year now and reckon I've done a few different tunes on my car, including...

• MAFed 100 RON tune ( Shell V-Power racing: may it rest in peace as it was by far the best pump fuel available.)
• MAFless 100 RON.
• MAFless E10.
• MAFless 98 RON

All tunes had the MAF in place and ran a "2 Hole Mod" on the air box.

With the 2 100 RON tunes, there was little between the tunes in performance and drivability. The big difference was getting the MAFless to behave nicely on the street. Currently I'm on the MAFless 98 RON tune and only have one bug to work out, which is a hunting idle just after a hot start. I have a bit on over the next few weeks but I may try a MAF 98 RON and see the difference now the rest of the tune is pretty much done.

I totally agree with you though, MAF or MAFless will come down to personal choice and specific application.

Simon.

[Gelf VXR]

I think the choice is closed loop vs open loop, and the MAF an associated choice.


CL (stoich) & PE vs OL (dynamic fueling) & PE

My choice is MAFLESS to remove the MAF as a restriction and OL speed density for dynamic fueling. I have an E40 and no custom OS for semi OL MAF tune.


Based of my data logging results, I have mapped my OL load table with (smoothed) screen shots below

idle 14.63:1 cells

lean cruise 15.4:1 cells (MAP)

Normal load 14.63:1 cells (MAP)

High load 13.5:1 cells (MAP)

I mapped PE to come in at 100 kPa vs ??% ETCTP and WOT

This is expermental, any feed back welcome

[joecar]

This is what I have when running 02020005 (COS5)...

I could probably lower the TP at low RPM on the PE Enable.

[Gelf VXR]

Hi Jo


Interesting, how did you arrive at your PE enable and load maps?

I did mine using cell count and by observing the load map in log replay, imagining the driving conditions for the cell activity.

I have added notes on the attacments to demonstrate my logic, be it right or wrong lol

[Highlander]

I don't like it... Although transient fueling is now available... having such a high value for the PE to kick in will simply heat up the pistons way too much and cause knocking.

[swingtan]

Is this thread drifting off topic?

There is a whole thread on PE activation here....

http://forum.efilive.com/showthread.php?t=6461