MAF limit reached @ 14psi

[Kooldino]

Ok, so I just made 250whp @ ~5K RPM hitting MAF voltage limit. 250whp is swell and all, but what bugged me is that I couldn't make power after 5K RPM due to the fact that my MAF freaked (says my OBD - II tool) due to the fact that it reached it's maximum voltage (4.7v?).

So in short, it kinda sucks that I can't rev my car out.

I need a cheap and EASY way to fix the problem.

I could go ghetto and wire a resistor in line so that it never reads past the point (we'll call it POINT X) that freaks out the MAF, now making the ceiling POINT X. Only problemn there is, that off boost, when I'm at say...2.5v, just driving along, it may now tell the ECU it's at say...2.2v, and thus run me lean. In short, I'd have to re tune my ENTIRE fuel map.

Ideally, what I'd LIKE to do is get a device that just acts as a voltage clamp. Something that inputs voltage and outputs the same voltage, EXCEPT in the case where the input voltage exceeds POINT X. In that case, it would simply output POINT X. Ya dig?

I could get a bigger MAF and retune the entire car, but that could be a PITA.

Any ideas?

 

[azian6er]

dont know about it but Joe P FCD?

-B

 

[boostisgood]

I think something along the lines of a voltage activated rheostat of some sort would work. I have not played with electronics in ages, so I could not tell you exacts on how to build, but it can be done at Radio Shack.

 

[Kooldino]

dont know about it but Joe P FCD?

-B

Doesn't that just lower the pressure that the FPR sees?

 

[Kooldino]

I think something along the lines of a voltage activated rheostat of some sort would work. I have not played with electronics in ages, so I could not tell you exacts on how to build, but it can be done at Radio Shack.

Go on...

 

[azian6er]

Doesn't that just lower the pressure that the FPR sees?

Definately not, that is the FPR. Thefcd tricks the maf so it doesnt see all the voltage. i bet it would work great for you.

-B

PS do a few searches on the fcd, it will help you out i think.

 

[boostisgood]

you would need to build some sort of mini chip type deal. A chip with an emprom burned into it that it will not adjust the rheostat until it sees like 4.69 volts. then it will not allow it to increase past that point. You will not hit the limit on it, and once you let off the throttle and the voltage drops, it will let go the rheostat to an open position to allow the corect voltage the MAF is putting out to goto the computer.

Like I said though, Its been years since I played with electronics, and I think that would work for you though if ya built it.

 

[Mr. Win]

pm'd ya

 

[PaulMP3]

maybe you could use a boost activated switch, that when in boost closes the normal route of the wire sending it throught the resistor. this way you could adjust the boost switch to come on at say 8-10 psi, and it wouldnt affect you off boost fuel maps.

 

[p5sundevil]

we cant use 3rd gen rx7 MAFs can we? I heard the TT MAF was set to 350whp max out or something....i know the BP guys can do this but I heard the fs couldnt for some reason.

otherwise i dont know.

 

[Kooldino]

maybe you could use a boost activated switch, that when in boost closes the normal route of the wire sending it throught the resistor. this way you could adjust the boost switch to come on at say 8-10 psi, and it wouldnt affect you off boost fuel maps.

I was thinking that yesterday. Basically using one of the FM clamps. But that's assuming that it only outputs POINT X volts.

 

[Kooldino]

OMGHI2U

http://forums.nasioc.com/forums/showthread.php?s=&threadid=40026&perpage=25&pagenumber=1

 

[Bigg Tim]

Ok, so I just made 250whp @ ~5K RPM hitting MAF voltage limit. 250whp is swell and all, but what bugged me is that I couldn't make power after 5K RPM due to the fact that my MAF freaked (says my OBD - II tool) due to the fact that it reached it's maximum voltage (4.7v?).

So in short, it kinda sucks that I can't rev my car out.

I need a cheap and EASY way to fix the problem.

I could go ghetto and wire a resistor in line so that it never reads past the point (we'll call it POINT X) that freaks out the MAF, now making the ceiling POINT X. Only problemn there is, that off boost, when I'm at say...2.5v, just driving along, it may now tell the ECU it's at say...2.2v, and thus run me lean. In short, I'd have to re tune my ENTIRE fuel map.

Ideally, what I'd LIKE to do is get a device that just acts as a voltage clamp. Something that inputs voltage and outputs the same voltage, EXCEPT in the case where the input voltage exceeds POINT X. In that case, it would simply output POINT X. Ya dig?

I could get a bigger MAF and retune the entire car, but that could be a PITA.

Any ideas?

The stock limit is 5v. I am hitting just over 4.9v now so maybe your readings are a little off, but either way you need to do something. The bigger MAF will do the trick but I agree on it being a PITA!!! Doesn't the turbo module have some type of ressitor in there to "cut" the MAF votlage?? I thought that's how you tune the stockers?

 

[SpicyMchaggis]

does a exhaust manifold that catches fire make extra power?

 

[Kooldino]

I don't have a turbo module.

I know it's a 5v sensor, but I'm told that anything past 4.8v makes it freak out. Perhaps one of the Beavis brothers can chime in here?

 

[Kooldino]

does a exhaust manifold that catches fire make extra power?

yes. it has firepower.

 

[SpicyMchaggis]

excellent..fire spewing from my exhaust wins the hearts of all the ricers.

 

[Little Beavis]

Dana, you're still running a MAP aren't you? If you ran the MAF through the tuner, you could clamp the voltage (it does this for you), then you wouldn't freak your ECU and you could still tune the way you've always done.

The turbo module does have a resistor in it, but in order to get it to read the MAF, you need to put a 1k resistor in parallel with the MAF signal (not sure why), so the module just does this for you. On a stock setup, just wire the resistor in parallel to ground and feed it into the tuner.

So, the solution for you is to use what you've already got????? Or am I missing something?

Edited for further clarification. Run the #88 MAF wire through the tuner. With the proper setting you can prevent the stock ECU from ever seeing anything above 4.7V (if you choose to set it there). Meanwhile the stock MAF will read higher (not sure how much higher, but I have had readings over 5V before with some of my experimenting). Anyway, the problem you are having can be prevented.

 

[starflare21]

excellent..fire spewing from my exhaust wins the hearts of all the ricers.

even better... colored fire spewing from the exhaust. lol

 

[SpicyMchaggis]

hmm, i dont know about that..but it is a neat little trick.