Afc and map sensor

[Likklekilla]

I would like to know when u use an afc and bigger injectors do u have to use check valves on the map sensor or missing link? I dont know how true it is but some say that the stock onda map sensor can take up to 11psi so why use Missing link or check valves?

[beerbongskickass]

You don't need check valves when your using larger injectors and the afc. Something about the larger injectors scaling the map sensor voltage so the car doesn't see boost. Try a search because I know TurboEF9 posted a few times about the afc and he knows his shit.

[turbobrain]

This is your boy jason, no u don't have to use a missing link when you use a afc with bigger injectors with up to 10psi. I took off my missing link when i statred using the afc with big injectors. The map sensors is what the afc use to change the air/fuel curve.

[TurboEF9]

So far, everyone has been correct.

You do not need check valves, or a missing link with an AFC and larger injectors.

What happends, is the AFC interceps the MAP sensor input signal, scales it back by the user defined percent, and feeds that "hacked" signal to the ECU. By doing this, the MAP sensor can use it's full voltage range (0-5v), and the ECU will never know the MAP sensor is seeing positive manifold pressure (indicated by a voltage reading above ~3.1v). This is why you do not need check valves or missing link. An AFC *must see* positive manifold pressure voltages from the MAP sensor to properly scale the signal voltage and give the correct fuel compensation.

As for the "limit" everyone talks about when they say, "how much can your MAP sensor handle", is not the physical limit, but the limit in how much pressure it takes to get the MAP sensor to it's maximum voltage reading. Once it reaches this limit, it will no longer increase voltage, and there will be no difference in fuel flow.

For instance, a stock OBD0 MAP sensor will read ~9.5psi. This means, the diaphram in the MAP sensor has reached it's upper limit, and the voltage is just about 5v (it will never truly reach 5v because of the physical design of the MAP sensor.. blah blah blah). OBD1 I believe is about 10.5psi @ ~5v. I don' tknow OBDII..

[FC_Drifter]

you certinly know your shit. Good explanation

[oscarmayer]

i think it depends on the yr car. With my obd-2 ecu I was forced to use a missing link (check valvec actually) to keep my map from seeing boost. Not sure why it was as earielr cars did not haev this issue, but I suspect it has to do with some new programmign and sensor monitoring capabilities of the obd-2 ecus. Much like being able to go to autozone now and get a cel light off a obd-2 ecu car and not an obd-1.

[TurboEF9]

Sorry, but no.

Your MAP sensor is a seperate entity from your ECU, and all Honda MAP Sensors are 0-5v throwing CEL at ~3.1v. The ECU may do "other things" with this information once it has it, but the if you install your AFC correctly, the ECU will never know the information was altered. Maybe something was wrong with your install? ..your AFC? ..your MAP sensor? I don't know. But I have installed plenty of customer's AFCs on OBD2 vehicles, all performed flawlessly.

Being able to use a scan tool on your ECU is a feature of OBD2 ECUs.

[botemarc]

so far great posts, now a question to you guys...
my current setup is a d16z6 head on a6 block...
i also have a jackson racing supercharger to be installed....
I recently finished wiring my vafc to my ecu. now with the JRSC comes the Boost Timing Control box which i also wired to the ecu and also a MAP Controller. Now, my question is, would the MAP and the VAFC not work well with each other...will one break the other...i have read that the Boost has no effect on the VAFC, so I am not worried about that....any reply from you genius men would greatly appreciated...i am planning to do the afc hack also, and I just want to make sure that the MAP Controller dont interfere with anything on my setup....thanks

ps...turboEF9, i'm really needing your "mind" on this...thanks

[TurboEF9]

Well, from what I understand, the MAP controller for Jackson Racing is an AFC of sorts. It's basically a MAP signal scaling device to allow the use of the Jackson setup on the motor with thier FMU, and no modification to the ECU (I.E. running code that has been rewritten to support boost.).

Now, the issue here is the the V-AFC, it seems, is what you were going to use to keep the CEL at bay. If you want to use both, I would 0 out the V-AFC, and use it for minor fuel correction, and wire the Boost Timing Control, and the MAP Controller up as they are supposed to be. Using the Jackson MAP controller to keep the CEL away.

Essentially using the V-AFC not as a "hack", but as it was intended; for minor correction of fuel. As if the car were NA.

...did that make and any sense, or do I need to clarify?

[botemarc]

Thank you very much for the reply...i understand the basics of what you said. So basically, it is safe to run the VAFC, Boost and MAP controller at the same time. Now my next issue is, i will be using the 450cc dsm injectors hoping that i can do the afc hack and i do not have the JRSC FMU because it didnt come with it when i bought it off of my friend. What settings or how would i setup the vafc for this kind of engine setup. If you have already any setups that I could use for the vafc, then i would greaetly appreciate it if you can share it with me. I know that every car is different as with my case too....I have just installed my new Comp Cam 59300 camshaft with AEM cam gear....i know this needs some timing to be done. But lets take these questions one at a time...let me know what you think again, as I really rely and believe your knowledge about these issues. thank you very much.