the diode mod

[hybrid_G4E]

it works fairly well for them?

Clamping the Map Sensor

taken from the same forum.
search for Diode Mod..

A diode is a very small electronic device with a voltage rating associated with it. What it does is regulates a voltage signal to its rating. For example, if you wire a 4.7 volt diode into a 5 volt circuit, the 5 volts enter the diode, and only 4.7 are sent out. The diode mod is a way to limit the amount of boost the ECU SEES. The ECU interprets voltage from the MAP sensor as boost. The max it is able to see on stock turbo programming is 5 volts. If it hits 5 volts, or if your boost level goes higher than what is spec’d, you’ll go into limp mode. By using a diode, you are regulating only the signal the MAP sensor sends to the ECU. By soldering in a 4.7v diode, the ECU will never receive higher than that voltage signal. 4.7v is equivalent to about 17psi. Therefore, if you want to run higher boost, once you hit 17psi, the ECU won’t know if you’re boosting higher than that by what the MAP sensor is telling it. Some tend to think a diode limits boost, where it’s actually limiting the boost the ECU sees so you can make more. It’s a very simple install

apparently a 4.3v diode will clamp at 11psi, which means our MAP wud never sees the boost cut as usual.

comments, anyone?

 

[dac69er]

its gotta be a zener diode to act like that. use a normal diode and its rather riskified.

 

[hybrid_G4E]

its gotta be a zener diode to act like that. use a normal diode and its rather riskified.

my bad!

yes it's the zener diode.

 

[spuddy]

At one stage I just put a Bleed onto the hose that goes into the MAP sensor, was running very close to stock sensor limits (think its 1.25bar) just used some copper brake line with a small hole drilled in it. Just so I'd not hit boost cut.

But if ur just lookin to raise the fuel cut, I think all FCD's are is a resistor to do something like wot u said.

 

[sdutton007]

If I put a zener diode on and set it to limit the boost the ECU sees to 12psi, wont the car run lean after that?

 

[GTti]

Yes

 

[GTti]

At one stage I just put a Bleed onto the hose that goes into the MAP sensor, was running very close to stock sensor limits (think its 1.25bar)

1 bar, it's a 2 bar MAP sensor.

 

[sdutton007]

is there any way to put one of these on and correct the fuelling WITHOUT a standalone ecu?

 

[GTti]

Not really, a FPR with a higher base pressure will do the job if it's just a couple of psi.

Not a RRFPR.

 

[HYBRID]

that diode wont work... fuel cut on the ep91 & ep82 is 4.15v

 

[dave123456789]

over here its a popular mod to remove fuel cut from cars, costs bugger all too.