Hi guys. I am trying to tune via wideband o2, but I have the weirdest problem. I cannot adjust fueling at all. It is just stuck at 0. It will not bulge at any set RPM level. I know the **** is not broken due to it being used for other functions, such as setting the desired RPM points. The password lock is not on either, because I can still alter RPM points, just not the fuel correction percentage. The car runs fine. Another important note is: my MAF sensor reading is constant at +4.8psi.

Please help. Thanks in advance.

 

Maybe you tapped the wrong wires for the maf.

 

I had a long conversation with steven88, trying to diagnose it, but we could not come up with everything. For testing purposes, I have unplugged the vafc from the middle plug, and the the car would not start. Doesn't that mean that the 2 maf wires are connected correctly?

 

I would just double check in the FSM wire diagram. It wont take long to do. Can you "reset" the vafc?

 

That doesnt sound right at all because I can start my car with it unplugged. It just wont rev past 2500 or so.

 

I am looking at this for reference.



Thanks for all the help so far, guys. We are getting somewhere.

EDIT: I'll try to reset it first.

 

You are right about this. If I unplugged the vafc, then it should be like I unplugged the MAF connector from the MAF under the hood. Or it should give massive hesistation, like what a bad MAF would give me.

 

I would like to omit the first unplugging test stated above. I must have left the ecu unplugged also when I tested it the first time while installing it.

I just tested it again. I unplugged the vafc and the car started fine. It DOES rev past 2500, like normal! From the two plugs, I unplugged just the bigger one (to keep power to the vafc) and all the readings go to 0, and the pressure reading goes to -15. What pressure readings do you guys get, in psi measurement, when it's functioning correctly?

 

Shouldn't it read voltage for the maf? I havnt messed with a vafc in a while so I dont remember.

 

It converts the voltage into a pressure reading. It can be set at different units. I'll triple check the wiring tomorrow.

Anything else would be helpful! Thanks, guys!

 

Unplugging a correctly installed AFC will be just like unplugging the MAF. SInce your MAF signal wire has been cut the signal breaks. If the airflow stays at one value its possible you cut a different wire to the MAF. But since I dont have a VAFC I cant tell you what the reading should be.


VAFC is for VTEC Hondas so it reads the MAP sensor pressure. SAFC reads MAF voltage but converts into % value based on MAF air flow. Running the VAFC on a MAF equipped car will work fine, but the air flow will always be displayed in pressure.

 

There is no one set pressure reading for the MAF because you can change the scale. Set the scale to +15 psi and tell us what you get then maybe someone can reference that for you. I would give you mine, but I have VAFC/MAF issues as well.

 

Oh yeah, and this is a good guide for initial settings if you want to check yours:

http://forums.maxima.org/showthread.php?t=461576


Some diagrams and discussion on the VAFC-II here as well:

http://forums.maxima.org/showthread.php?t=463936

 

Thanks so much guys. I got the problem fixed. When I first installed it a few weeks ago, I didn't count the pin 63 because there is a blank pin space there. So when looking/counting from right to left, I thought pin 61 was pin 62 for the maf! I spliced to the correct wire, so it works perfectly. I am in the process of tuning the car via wideband. It's fun. Thanks again.

THe pressure readings are: -12.7 psi when the car is off. Idles at around -2.0 and positive when reved.

 

did u cut the MAF wires or tap them

edited

 

You need to cut the MAF wires in order to intercept and alter the MAF signal via the AFC. I don't think there's any way around that, unless I'm misunderstanding the question.

 

It is tuned now on about 5 street pulls. It feels quite a bit stronger than better the tune. It was running rich before the adjustments. I will take it to the dyno to see how much power I'm making.

 

Well thats y i am asking cause if he didnt cut them his fuel corrections arnt doing anything ...well atleast they are only being corrected for a short period of time until the ECU corrects itsself......and are u tuning with a wideband or anythign to monitor air/fuel

 

He's using a wideband.

http://forums.maxima.org/showpost.ph...1&postcount=14