zener diode mod

[96 420a-t]

Any one heard of using a 4.3v zener diode between the ecm signal and ground wire to limit the voltage the ecu sees from the map. I see that many people are doint this on dodge cars. Any one have any thoughts or experience?

 

[VelocitàPaola]

Any one heard of using a 4.3v zener diode between the ecm signal and ground wire to limit the voltage the ecu sees from the map. I see that many people are doint this on dodge cars. Any one have any thoughts or experience?

They typically use one reversed biased Zener diode and two forward biased signal diodes for the voltage drop. It works, but it's a very quick and dirty circuit. You ideally want something adjustable that buffers the voltage. Real FCD's aren't expensive these days, so there's no reason to mess around with this hack unless you're really in a pinch.

 

[96 420a-t]

I'm unemployed and all I can find on egay is 120+ dollar fcds.

The way I saw just used one. Hooked between signal and ground. For 1.59 I'm gonna try it.

 

[silvreclips]

You can get them for about 20$ all day long. I know guys on 2gnt sell them

 

[96 420a-t]

I looked and was unable to find any. I'm just at the point where I'm throwing parts at my car. I am getting soo frustrated with this car I'm ready to set fire to it and cut my losses.

 

[96TurboGS]

Here’s something to get you started:

Voltage Clamp

If you don’t have the proper test equipment or know how, you may want to leave it to someone who knows what to do. Again, cheap solutions.

 

[96 420a-t]

I tried that messed it all up and burnt the shizz out of myself soo many times.

 

[96TurboGS]

So, I went ahead and made the circuit a while ago and it runs fine. Maybe you were shorting something with a low pot value or maybe a supply line? Don’t mind the first pot before the first comparator, it’s just there so I could simulate the voltage. It’s clamping the voltage:

 

[96 420a-t]

Wow. Not even going to attempt that.