I'm getting ready to tune my APS TT G35 and have been told that due to the MAF sensor the Unichip is very limited on its tuning ability.

So, I started thinking about it, and it seems logical that it would be possible to install a MAF with a wider range to improve the resolution of the Unichip.

The downside to this is that the stock ECU won't like the new MAF range.

Is there anything out there to scale one MAF sensor to another?

 

From what I've heard the MAF maxes out pretty quick when on boost. Something like 5-6psi (I think).
Don't know if a UTEC would be an option for you but a system like that would allow you to run MAP once you're into boost yet retain the MAF for good driveability and idle off-boost. I think you may be able to eventually go all MAP and ditch the MAF completely when they release their temp sensor. Only benefit there would be "0" restrictions and the ability to run larger intake piping if you want. Little more trickier to tune though..
Just a thought..

 

The MAF max voltage depends on the CFM the turbo is producing. On some kits its 15 PSI on others 8. It depends...

 

Gotcha...Hate to pass on erroneous info.

 

No worries dude. The real problem is factoring ambient air density. Because this will affect the total CFM seen by the MAF. For instance at 95 degreed F ambient the MAF me be able to read say 14 PSI and the CFM to go with it (from the given turbo) but at the same pressure but say 45 degrees F ambient the CFM may be higher due to denser air and the MAF will max sooner...

 

Unichip has a map sensor so the Maf is not a big problem on the APS TT cars. I think a great idea for the TN kit would be bigger injectors, slightly bigger turbo and Lightning MAF. Of course this would take another reflash. Maybe call it a stage 1.25. LOL.

 

Actually Turboentics is soon releasing Stage 1.5 with a tuneable EMS that clamps the MAF voltage so the MAF issues are no longer an issue. Also comes with bigger injectors and a fuel return system.

 

has anyone tried running a MAP sensor on a FI z yet?

 

MIA, I'm not sure I agree with CFM being higher with colder air. I understand where you're coming from but I would think that CFM stay always the same, no matter what the temperature is.

I do agree that the density of the air changes and with that, the amount of oxygen is higher in the same amount of air. Volume of air is constant, the distance between molecules is variable, hence higher density in colder temp.

 

That is correct I think I confused myself with that post.... The air is DENSER therefore even though the flow rate of the air is unchanged and the differntial pressure is the same the air is in fact more dense. However because of this turbo systems running on wastegate alone will see an increase in boost pressure (although sometimes very small ones) and the increased air density is certainly corrected for via MAF sensor temp readings. What this all works out to is in cold weather you may see 9 psi as opposed to your normal 8 PSI and the MAF will max however at the same 9 PSI in warmer temps the MAF will read it without error.

 

HKS Vpc will get rid of your maff, so will a HKS vpro

 

I actually thought about the VPC but I thought it was getting discontinued from HKS product line. I would be interested in doing a V Pro but I think I'll hold off on anything like that till my built motor goes in.

 

The unichip- clamps voltage on the MAF, no worries there..

 

Hey Kevin, as some others have mentioned, the UNICHIP, UTEC, and EU are all using MAP sensors to tune the engine. So no reason to change out the MAF sensor.

Best of luck!

 

i picked up another stock MAF a little while ago. This year I am going to experiment with the FCONs dual MAF capability. I would prefer the car to run MAFs if they dont max out at the HP level.

-charles

 

I have a question regarding this. If the MAF's max out at like 9psi, then what happens when your boost spikes? Does your ECU not know what to do and you run lean?

 

Good experiment... Seen some of your dual intake ideas...

Please keep us posted..

Cheers Amy -

 

OK, I read the Email from GRD wrong I believe. Here is what they told me:

"The unichip uses maf voltage to control fueling therefore the complete system is limited by the maf size"

Reading this again I'm left believe that the Unichip adjusts the MAF voltage to control fuel based on what it is reading on its MAP sensor. So, nothing I could do the MAF would fix anything (short of reflashing the ECU with a new fuel table).

This sucks, I was thinking I was almost done and only had one big purchase left (clutch). Now, it looks like I'm going to go with the UTEC or something similar. Does anyone know if there is a market for a used Unichip?

 

MAF's max out at a certain voltage which after taking in account the housing size is how much air the ECU can actually meter. It has nothing to do with PSI other than the fact that the more boost you run the more air will be sucked in at a certain RPM. Example 15psi at 3,000 rpm will most likely not max the MAF out(limp mode because of the voltage to RPM correlation is another thing), while 12psi at 6,000rpm most likely will. Another is at 3,000rpm and 8psi it is sucking in far less air than 8psi at 6,000rpm even though the boost is the same. A MAF sensor measures just what it says Mass of the Air Flow. Hope this makes sense.

 

Kevin, in addition to clamping the voltage, the UNICHIP adjusts fuel by adjusting the MAF voltage. So you are correct, in that at some point...probably about 500whp, you will not have enough resolution to make the adjustments to the MAF in order to enrich fuel. If you are running larger injectors, you will be starting with -50% MAF voltage, which give you quite a bit of tuning room...all the way to 50%.

But, IMHO, on a high powered motor, such as they one you have built, I would definately be looking at a UTEC for tuning purposes. It's feature set is far more robust that the UNICHIP, and it acts as a full stand-alone, with full control over fuel and timing...no exceptions. Even if you find a larger MAF, controlling fuel via MAF offset on the UNICHIP is a less precise method of tuning.

The UTEC with MAP sensor is about $1050, which makes it a very reasonably priced approach.