limp mode mod

[Rickie3]

Just an ordinary diode, fit the silver end away from the MAF sensor, and yes it does work

[Rumcajs]

Just an ordinary diode, fit the silver end away from the MAF sensor, and yes it does work

I'd like to know how it works because a diode is "electrical one way valve" and not a resistor. So my understanding is that at best it blocks the voltage/current one way and let it flow other. So what is changing?
Do you have a means of reading MAF signal? If you do, how is the diode affecting the value?

Cheers

[oddkid82]

So does this cut out the cold limp mode. I get limp mode on cold mornings only in 3rd gear going up a slight hill.

[mudski]

I'd like to know how it works because a diode is "electrical one way valve" and not a resistor. So my understanding is that at best it blocks the voltage/current one way and let it flow other. So what is changing?
Do you have a means of reading MAF signal? If you do, how is the diode affecting the value?

Cheers

Yeah I'm confused how a blocking diode will work.

[Yendor]

I'd like to know how it works because a diode is "electrical one way valve" and not a resistor. So my understanding is that at best it blocks the voltage/current one way and let it flow other. So what is changing?
Do you have a means of reading MAF signal? If you do, how is the diode affecting the value?

Cheers

A characteristic of a diode is it will also have a voltage drop of 0.5 to 0.6 across it.

So in theory you should also see this voltage difference at the ECU.

[Pokey]

Ok I just tested the diode theory. No limp mode at 20 psi. BUT very sluggish engine. I'm guessing with the lower maf voltage through the rev range the ecu is not allowing the required fuel needed.

[Rickie3]

A characteristic of a diode is it will also have a voltage drop of 0.5 to 0.6 across it.

So in theory you should also see this voltage difference at the ECU.

That is correct! EGR blocking increases the voltage to the MAF, the diode drops the voltage by 0.5 to within specs, but yes you will notice sluggishness, but me I can put up with that, far better than hitting limp mode

[Pokey]

I haven't blocked my egr yet as I'm waiting for a mod plate inspection from the transport dept and it won't pass with egr blocked. So with egr blocked plus diode , voltages should be back to nearly normal. Btw i can't live with a sluggish engine. After spending thousands of dollars chasing more grunt sluggish isn't an option. I have a diesel smart interface that caps the maf voltage just under limp mode but I'm not convinced that I'm getting full fuel delivery after the voltage cap. Still playing with ideas and probably doing what many have done before but I think these little Renault engines are capable of some serious pulling power if they are treated right

[mudski]

Will the transport dept actually check if the egr is blocked? They would only know if they remove the pipe.

[Rumcajs]

.............. I think these little Renault engines are capable of some serious pulling power if they are treated right

You will find that these are not Renault engines at all, just pure Japanese POS. ZD30 has very strong bottom end (crank, big ends, block etc) but the pistons are made from Rockford cheese. Therein is the problem as majority of ZD30s expire via hole in the piston.
If one could source cast iron "skeleton" type pistons you could push that engine to 200 hp easily.

Cheers