Maf Conversion Issues

[TOTGAS]

I need some help and information from those that are more knowledgable. I am building a custom efi system which requires an Air Temp Signal #2 off and a Maf signal. I am running a water/meth injection unit which has multiple triggers a) Air Temp B) RPM and an C) Vacume trigger, this is running inderpendantly of my ecu. Now the ecu requires a Maf signal. From what i have read on the net most Maf units have an air temp signal incorperated with them and the intake air temp is what dictates the mass air flow signal to the ecu. My water/meth injection is injected directly into the plenum chamber, which will give me a much lower air temp ( #A degrees) Yet my Maf unit is supposed to be located near my air intake box which wil give my ecu a higher Air Temp reading (#B degrees) Hence the signal to the ecu will not match the actual temp inside the plenum chamber. Q1 is there a Maf unit that does not have an air temp signal incorperated with it. Q2 or will i have to relocate my water/meth injection so that it injects prior to the Maf unit. Or does it not really matter and i am concerned for nothing ??? ny help and or information is good thanks

[George]

A few degrees error of air temperature reading won't make your engine run any worse, don't worry about it.

[TOTGAS]

Thanks George,
around the eastern coastal areas and down south it might not be to much off an issue. Although in central Australia and WA in the desert areas where the ambient air temp is a lot higher and drier (45c+) it might have a noticiable difference. Direct injection into the plenum will keep the plenum cooler, running 50% water and 50%meth, it comes out as a mist @250psi and on my hand it was very cold. I just don't want to make any bad mistakes, the BMW guys and their techies go right into Maf sensors and according to them and Bosch the maf sensors are calibrated to the vehicals intake design and requirements. Yet they could not tell me if a Bosch MAF Sensor would even work in my application, apparently a maf sensor isn't just a maf sensor, it needs to be the one designed for your vehical (mine never had one) it originally was a carbie mod.
Nice car watched the video, now that snow driving looks like fun even if it is a bit slow lol.

[RT40Corona4AGTE]

is there any reason you cant ditch the MAF sensor and use a MAP sensor and IAT sensor in the plenum?

If you are building a custom ECU then it would probably prove beneficial? Or do you mean you are running a factory ECU in a custom configuration?

More info required please? I am more then happy to help with this though.

[madmont]

As I understand it the MAF measures the airflow and the temp is measured and used by the ecu as a correction to give a trueer estimate of the air mass to which it has to add the correct amount of fuel. I cant see that it makes any difference to the air mass if it is cooled after it has been measured by the MAF . It will still be the same mass just a different volume.

[TOTGAS]

The ecu is a Dicktator from Sth Africa with a TP 100 igniter. Although it does require a air intake input, water temp input TPS input. With the TPS unit i do not believe them to be reliable enough on there own.
Later down the road i want to put on a 5-8psi s/charger.
With the water/meth injection unit i have a IAT unit located in the plenum.
So what would be better MAF or MAP in my situation, everything on and in this motor is brand new and not from china either at the moment it only has 1 1/2hr bench/run time and 27ks with a webber on her, now its efi.
Remembering that it is an 89 4y, with 96 Spacia efi, Sth African ecu, water/meth inject (usa) and custom air intake. She was built for reliability, with some extra grunt, and not to rip up the tar :-)

[RT40Corona4AGTE]

If the "Dicktator" (funny name for an ECU) can take a MAP signal, then go MAP sensor IMO.

[madmont]

My 1JZ has a MAP sensor and has the IAT in the air filter box. VN commodore has a MAP sensor and the IAT is on the manifold

[George]

TOTGAS,
the slow snow video refers to the period the car was fully stock and it was even different color :-) and quite dirty, though after a wash it's a matter of some 20-50km here )

As for the specialized MAFs. As far as I know you don't worry about MAF reading being correct if your MAF appears like tube with a sensor inside, so you are meant to connect round air ducts to both sides. However there are MAFs that are meant to be side-mounted into specific place of intake system of particular car. I think only the latter are sensitive enough to intake configuration.

Now for the MAP/MAF problem. Two mates specialize in tuning inline-fours (136hp stock at crank) into 180-300hp at rear wheels. They redesigned stock ECU, in particular it now reads one MAP instead of one MAF. According to their report, a MAP-driven ECU system in general has quicker throttle response, does not depend on air flow magnitude, and allows for different schemes of turbo pressure adjusting (blowoff, bypass system etc). However a system without a MAF has much less possibilities to self-calibrate, and thus it's very sensitive to such things as valve timing.

I have read some American forums on converting carby cars to EFI. Folks there went so far in making things simple that they just picked up MAF-driven EFI from an engine of appropriate displacement, installed everything, replaced water temp sensor with a potentiometer and went joyriding ) Keeping all this in mind, for a first experience without a need to push the car to the limit I would prefer a MAF.

[TOTGAS]

Thanks George

You have given me some serious brain food on this issue. Later on I intend to put on a small s/charger (no turbo) only 5-8psi max just for a little more uphill grunt, this is always in the back of my mind whilst I have been building this project.

Firstly I will get in contact with the makers of my ECU and ask for their "professional" opinion as to what direction to travel, MAF OR MAP. In a manner of speaking i am limited as to bolt on extras being as my motor is a lowerly 4y. Standard 91hp, on paper @ moment 120hp, I am now at the tuning stage. Hence the MAF & MAP issue and dizzy configuration, then the dyno to bring it all together.

I would say I have a lot more home work, thanks for your imput George very much appreciated

[George]

btw how do you plan to tune your system to the right AFR? (Innovate LM-1 for example). Will your system use oxygen sensor input?

[TOTGAS]

I purchased a AEM Wideband O2 + Gauge from SummiT Racing (AVM 30-4100) USA

[George]

Great! This increases your chances to successfully run MAP system. Ox.sensor (that for everyday use, not the wideband one) and short/long fuel trim ECU feature will be good companions as well.

[TOTGAS]

This was a complete kit, with a Bosch O2 sensor which i have already fitted, after doing some home work as to the correct placement of the O2 sensor.

I have not got to the ECU yet, they sent me the software and a couple of fella's sent me their maps, Just to get me going being as there are a few modifications out side standard done. I will have to eventually get it dyno tuned to bring it all together.

But i am old school so this is a huge learning process for me.

[TOTGAS]

I do have a question as silly as it my sound, if i run a MAP set-up and later a small super charger will a vacume gauge be any good to me or do i have to get a boost gauge ??