Dreidel

ok so after doing some research on the idea everybody is always wanting to convert to maf which according to most people cant be done without very expensive translators and stuff like that here is my idea

generally map (manifold air pressure) run the same voltages as the afm which is i believe 0-5 volts right (correct me if im wrong please) so does the map so if you could pinout the connector for the afm you could make a adapter for a map sensor (and not to forget the temp probe in the afm) then pop the temp probe out of a junk yard afm and place it somewhere of your choice in the intake plumbing so in theory this should work right?

i will probably try it out soon and if it works out i will do a write up

if anybody sees any flaws in my plan feel free to point them out please cause i hate that bulky ugly thing under my hood plus a cone filter right on the throttle body would look awesome on a 22re imo
on paper i think it sounds good what do you guys think

worshipmentor

iTrader: (3)

Curiously subscribing.........

Dreidel

ok so just priced a afm on ebay and dont know if i really want to spend 110 money on a "possibly, might work project" ya know... so it might take a while to find one cheap but there will be one eventually and either a write up link and pictures or a message saying need help!!! will appear

Dreidel

oh and if somebody could supply a pinout of the connector on the harness for the afm and a list of what each pin does please i have seen a pinout but all it say is like e1 e2 and stuff like that

worshipmentor

iTrader: (3)

The pin out should be in the FSM the is available digitally on the website.
As to an AFM to test with I have a spare stock one from a 22re (87) and one from a 3.0 (88). If you could make this AFM/MAP swap work I'd let you have one for shipping to experiment on BUT if you can't make it work I'd want $25 for the AFM.
Let me know.

MudHippy

1. MAP(Manifold Absolute Pressure)
2. Same 0-5V signal as a VAFM, but reversed. Starts low then increases as air flow increases. Whereas a VAFM starts high then decreases as air flow increases.
3. Doing this conversion with the stock ECU isn't going to be easy.
4. Doing it with MegaSquirt® would be much easier. But also much more expensive.
5. Don't forget the fuel pump switch.

EDIT:
2. The VAFM on a 22R-E uses a 0-12V signal. Starts low then increases as air flow increases.

Dirt Driver

1.) Especially without some way to alter the programming. VAM to speed density(MAP) or even MAF conversions have been done with mid-'80s Ford turbos, but there are numerous chip/tuner options for their EEC-IV system. Not the case with old Toyota trucks.

2.) Much more effective, too.

I'll add that putting a cone filter right on the TB will make the engine suck hot air from behind the radiator. The factory intake is already a "cold air" style. The gain from ditching the VAM on a relatively stock engine is going to small at best. Weigh what you have to gain against what it's going to cost in time and money and I think you'll discover that it's not going to be worthwhile.

Dreidel

the fuel pump switch is the temp probe isnt it to tell the pump when air is coming in right?

MudHippy

No.



See also the 22R-E VAFM section from the FSM.

And I was mistaken about the type of VAFM used on the 22R-E. It's actually the other type. With a 0-12V signal, that starts low and increases as air flow increases.


I'm not the expert on the 22R-E that I am on the 3VZ-E...

Dreidel

ok so if it operates on 0-12 why cant a maf be used with a fuel pump switch too

Dirt Driver

That would work if you found a MAF sensor with the exact same transfer function and output as the original VAM.

Numbchux

This seems like a lot of work, for some hotter intake air temps (i.e. less power).



A flow sensor measures (as the name implies) the volume of air going in before the throttle body. This is essentially a linear function that increases as the throttle opens and rpm rise.

A pressure sensor measures (again....) the air pressure in the intake manifold after the throttle body. This is not linear. An N/A engine pulls a vacuum with the throttle closed. Then when the throttle plate is opened, at low rpm the manifold pressure goes up to neutral, then as the rpms increase, the engine pulls more air volume in, which is more than can flow through the intake plenum, which means the manifold goes back into vacuum.



So, the programming has to INTERPRET the signal correctly, by calculating the flow rate based on the pressure, rpm, throttle position, and air temp. From your posts, it sounds like you just want to hook up a MAP sensor to the AFM signal wire.

Dirt Driver

I think transfer function is getting mixed up here with a graph representing measured airflow for a given engine. You'll find that the only one of these three sensors having a relatively linear transfer function is actually the pressure sensor, although VAMs can have either. MAF sensors have a quadratic response curve. Any graph of MAF and some VAM output for an engine isn't going to be linear for that reason and because airflow through an engine isn't directly related to RPM.