Air/Fuel ratio adjustment?

[///Mariani]

Is there a way to adjust or reset the fuel air ratio. I just got the MAF sensor in and with a cold air intake she idles fine but the slightest tap of gas and she dies. My guess is that its running leaner than the computer wants, because without the MAF, it runs fine, a little low on power i think though. Is there a way where the computer can learn whats going on and enrich the mixture a bit? I have the remote electric FPR 3.5 bar I think. Stock e30 318 fuel pump, S52 OBD2 intake. I figured the computer would adjust by using the FPR to adjust to more air comming in. I honestly dont know how it works.

[e30rapidic]

maybe your MAF is on backwards?!? Check the directional arrow

[///Mariani]

I have it to where the arrow points aft of the car, toward the throttle body. Im assuming that is correct? I figured with the airflow is correct.

[328ijunkie]

^correct.
MAF is either wrong or you have VAC leak

[///Mariani]

Ok, so I did some troubleshooting and here is what I have so far. First ill start by saying that my intake isnt fully completed as in I had to improvise with and autozone intake boot just to test some things out, so I dont have an ICV line port to go inline with the MAF. Inno some of you will point directly to that, but will that matter? I will get the OE boot eventually but for now, I just stuck a mini filter on it and left it to the side. Like I said it idles fine but dies when gassed. So checking for leaks, none were apparent where the intake meets the head, but I did notice that even when the throttle body is closed, I get a significant amount of suction from that thing. So much so that I have to use force to get it to let me go. All improvisation aside, is that normal? I even took all ducting down to just bare throttle body and same thing. The damn thing nearly pulls me in. And this is with absolutely no throttle actuation and ICV isnt inline. It will still hold idle also(with no MAF). When I do give it some throttle, It will die as soon as. So then I put all the ducting back on including MAF but left the filter off and of course ICV is dangling on its own and blocked airflow again, this time at the MAF, and it instantly dies even with no throttle applied. It sucked my hand in too before it died. Then I tried giving it throttle without the filter, MAF was still installed, and it revd up, struggled a bit but kept going, then I let i go and it dies. Did it a second time and it tried to rev again, struggled a little, then died while still having throttle pull. With the filter on it dies the instant i pull throttle. I would like to think that the ICV not being inline with the MAF would be the problem, but it idles just fine with or without the MAF hooked up. So I guess my questions are, Do I have a real problem with that suction being at the throttle body with no pull, or do I have to get the computer reflashed for a different fuel air mix, or am I just causing problems for myself by no having the ICV hooked up in line with the MAF?

[328ijunkie]

Sorry but yes. Do a little reading on how a MAF system works. In addition to what a vacuum leak is as youve just created a massive one.

[///Mariani]

Are you saying that because the ICV is drawing air elsewhere, that the computer sees it as a leak? Im sorry but you have to dumb this down for me and beat it into my head. My motor swapping skills have dulled since the last time ive never done one.

[nyChris]

All the air entering the intake needs to be metered by the MAF, or the engine will not run properly, or "die". In your scenario it sounds like there is air entering the system after the MAF, which is causing un-metered air to enter the engine. Due to this un-metered air, the ECU has no idea how much fuel to provide the engine to reach a proper air/fuel mixture.

Echoing 328ijunkie, you should do some research on how electronic fuel injection works.

[///Mariani]

Ok will do. Thanks for the clarifications. And please bear with me.

[///Mariani]

That was crazy enough to work, thanks guys. The computer definitely adjusted the mix, because when I let off of the gas, I get popping out of the exhaust. I just did a small test drive because Im only running headers out of the motor until I can get it to a shop and complete the exhaust and I dont want to do any damage.