filetofit

http://angelfire.lycos.com/ab7/diymaplimiter

The first circuit is a MAP limiter. It electronically limits your MAP output so the ECU never sees more than 3 Volts. It eliminates the need for check valves, missing link etc. It can be used to run 450 cc injectors but the idle is rough. The second circuit allows you to run 450cc injectors, idle nicely, run as rich as you want at WOT, and incidentally it acts to electronically limit the MAP voltage that the ECU sees to 3 volts. I'm currently using the latter circuit with DSM 450cc injectors on an LS/Vtec turbo running 9 psi. I should mention that my closed loop is disabled however.


PS I'll send anyone who wants one a built circuit for $20.


[Modified by filetofit, 6:21 PM 7/23/2002]

chad

thank you much....this has been filed for further informational purposes!

filetofit

Fine, but tell me... how do you type one handed?

SlowB16

You splice into all three map wires right?

filetofit

Correct, actually to be precise, you tap into the +5 volts and ground wires, and you cut the signal wire and splice the circuit in between the MAP sensor and the ECU.

DJ0820

Can u run this with just an FMU?

Later,
Derek

filetofit

To run it with an FMU it would be setup as an electronic MAP limiter so you wouldn't throw a CEL.

ion_four

How do you have the closed-loop disabled? What kind of mileage do you get with that set-up? I plan on doing some serious driving and was probably going to use this...

Good job, man!

filetofit

I've got my closed loop disabled with an aftermarket chip in my ECU. The circuit doesn't disable closed loop. But if you're going on a long trip and you want great mileage, turn down the circuit adjusted MAP output voltage, you'll run lean so don't boost.

PS my mileage sucks (20 mpg) but I boost from every stop and hit 100 mph+ everyday on the way to work plus I've got disabled closed loop. With enabled closed loop you're mileage should be stock as long as you keep your foot out of it.


[Modified by filetofit, 7:27 PM 7/26/2002]

DJ0820

Wait, so your saying that with the 2nd circuit you can run the 450's driectly from the stock ECU?

Later,
Derek

filetofit

Correct, the second circuit does the same thing as the VAFC hack. It allows the use of 450cc injectors on a boosted engine by reducing the MAP sensor signal to the ECU. Also thereby eliminating CELs. More specifically it cuts the signal by about -20% at idle and about -45% at WOT. You can adjust this however.

technine

I'd be very interested in it, do you have any pics? How is it adjustable? Is there RPM individual settings that you can adjust or is it an idle adjustment and wot adjustment or leaniuor (spelling)?

filetofit

No pics, no digital camera. But it's about a two inch by two inch circuit board with a chip and three pots on it. It doesn't use RPM as an input it just tweaks the MAP signal by -20% at idle, -45% at WOT. So when the MAP sensor puts out 1 volt (idle) the ECU "sees" 0.8 volts. When the MAP sensor puts out 5 volts, the ECU "sees" 3 volts. It linearly interpolates points in between. I figure if people who are using the VAFC hack are just setting it to -50% across the board, it's easy to do that, you don't need a VAFC.