Diode trick

[QuA]

Has anyone done a diode, mbc trick, 4bar FPR? Just reading on the forums and people are getting some really sick #'s without a chip.

Dyno's of 200whp without a chip?

QuA

[Aleks]

Re: Diode trick

huh? I'm not too sure what the diode thing is, could you explain a little more??

[Simon]

Re: Diode trick

Has anyone done a diode, mbc trick, 4bar FPR? Just reading on the forums and people are getting some really sick #'s without a chip.

Dyno's of 200whp without a chip?

QuA

alot of people wont give out specifics on how to do it because it is very dangerous to do if you dont know exactly what you're doing. mod at your own risk

[Khyron]

Re: Diode trick

I think it basically tricks the ECU into thinking your pushing half as much boost as you really are. So you double your boost more or less (which if done alone would make you lean), which is why you use the 4bar FPR (which alone would make you run rich). Sounds great on paper, but it's a balancing act for the entire rpm range - what balances at one rpm won't at another. And the biggest risk is if something goes wrong, the ECU puts you in limp etc so you don't blow crap. You're bypassing all that.

Plus, I don't see how a MBC, 4bar FPR and the extra gas + time and risk is worth less than the 500 bucks or whatever it costs for an Upsolute.

My opinions anyways...

Khyron

[Kor]

Re: Diode trick

Has anyone done a diode, mbc trick, 4bar FPR? Just reading on the forums and people are getting some really sick #'s without a chip.

Dyno's of 200whp without a chip?

Dangerous.

The "chip level" of about 15-16 psi is pretty much the highest you can safely run your stock turbo and expect it to have a long life.

[Kor]

Re: Diode trick

A better way to do this trick (IMO)

- Replace your MAP sensor with a 3.5 bar MAP sensor
- Replace your MAF housing with a VR6 one
- Larger Injectors

Essentially you would be scaling the entire system by 30%. The diode trick makes the ECU think you have only 14 psi of boost at all times, and it will not increase fuel beyond that requirement. A FPR will not help, since it will make you run really rich below 14 psi, hurting performance, economy, possibly causing damage too. I do not think that the "diode trick" is really going to work for a daily driver. Maybe it will work for 1 dyno run.

Even the above setup may not work.

[seanfournier]

Re: Diode trick

A better way to do this trick (IMO)

- Replace your MAP sensor with a 3.5 bar MAP sensor
- Replace your MAF housing with a VR6 one
- Larger Injectors

Essentially you would be scaling the entire system by 30%. The diode trick makes the ECU think you have only 14 psi of boost at all times, and it will not increase fuel beyond that requirement. A FPR will not help, since it will make you run really rich below 14 psi, hurting performance, economy, possibly causing damage too. I do not think that the "diode trick" is really going to work for a daily driver. Maybe it will work for 1 dyno run.

Even the above setup may not work.

I agree. Clamping (the diode thing) is not the best idea to follow but it does work. I'm clamped right now with 4.7V 5W. I don't get over boost codes anymore. A/F is actually real good too.

the way it works is the MAP sends accurate readings to the ECU all the way up to - this is where different voltages of the zener diode come into play - the pressure/voltage limit. The zener diode will not let a voltage signal greater than eg. 4.7V to be sent to the ECU. You could be boosting high enough for the MAP to be sending a 4.9V singal but the diode clamps it down to only 4.7V gets to the ECU.

Keep in mind that if you had your MAF disconnected this would probably be pretty risky business to try because then the A/F is quite dependant on just the MAP readings. Leave the MAF in, get a wide-band oxygen sensor, and clamp away.

[Khyron]

Re: Diode trick

I agree. Clamping (the diode thing) is not the best idea to follow but it does work. I'm clamped right now with 4.7V 5W. I don't get over boost codes anymore. A/F is actually real good too.

the way it works is the MAP sends accurate readings to the ECU all the way up to - this is where different voltages of the zener diode come into play - the pressure/voltage limit. The zener diode will not let a voltage signal greater than eg. 4.7V to be sent to the ECU. You could be boosting high enough for the MAP to be sending a 4.9V singal but the diode clamps it down to only 4.7V gets to the ECU.

Keep in mind that if you had your MAF disconnected this would probably be pretty risky business to try because then the A/F is quite dependant on just the MAP readings. Leave the MAF in, get a wide-band oxygen sensor, and clamp away.

The trick is finding a wideband o2 sensor that doesn't cost a fortune - what do you have?

Khyron

[seanfournier]

Re: Diode trick

The trick is finding a wideband o2 sensor that doesn't cost a fortune - what do you have?

Khyron

my wide-band unit cost me about $350 all said and done.

[Kor]

Re: Diode trick

my wide-band unit cost me about $350 all said and done.

Ouch.

On a related topic, I don't think replacing the MAP sensor will work, it causes too many problems under vacuum/idle. Simon's idea of using an audio compressor circuit is a good one (better than anyone has come up with on Vortex). Howver I have the feeling that finding such a circuit and making it portable is much harder than one would think (there don't seem to be many out-of-the-box components of this type available). It is a fairly complicated circuit with very specific requirements (from my perspective).

Some people on Vortex seem to think that the MAP is not involved in the fueling calculation. If this is true, then it may be totally safe to clamp the MAP sensor wrt fueling. There is still debate on this. Another issue is timing... but the ECU can probably handle that...

[Kor]

Re: Diode trick

If someone is thinking about trying this, check out this link:

http://www.teamfc3s.org/info/articles/fcd/diy_fcd.htm

A simple circuit for clamping the MAP, better than just using a diode. Finely adjustable, probably to about 0.05v, and cheap to build. I guess there could be danger in adjustability though

[seanfournier]

Re: Diode trick

If someone is thinking about trying this, check out this link:

http://www.teamfc3s.org/info/articles/fcd/diy_fcd.htm

A simple circuit for clamping the MAP, better than just using a diode. Finely adjustable, probably to about 0.05v, and cheap to build. I guess there could be danger in adjustability though

excellent artice. okay, someone ELSE go try it now

[Kor]

Re: Diode trick

excellent artice. okay, someone ELSE go try it now

I am still working on my MBC setup... its in the car right now, however I am having problems due to the weather. I adjust everything just right, then the outside temp drops or warms up 10 degrees and suddenly I am either underboosting or in limp mode... I am running a spring/ball MBC in parallel to the N75 with a pressure regulator before the wastegate.

I will probably try running it without the N75 next week, and I will also try to order a better relief valve that hopefully is more constant in different weather conditions.

If I can get my boost level nice and constant, then I will mess with the MAP to try to bump it up 1-2 psi. I don't want to remove my safeguards while my boost is bouncing all over the place.

[Khyron]

Re: Diode trick

my wide-band unit cost me about $350 all said and done.

That's pretty cheap - I've seen a few on vortex and they were all 500 US + for the sensor and a gauge. There's a nice LED slider that goes from green to red that would be nice to get (after more mods make it needed of course).

Khyron

[seanfournier]

Re: Diode trick

That's pretty cheap - I've seen a few on vortex and they were all 500 US + for the sensor and a gauge. There's a nice LED slider that goes from green to red that would be nice to get (after more mods make it needed of course).

Khyron

my wideband unit has provision for a autometer type gauge (0-1V) to show you the scale without having to read the numbers. Kinda like buying a CD player and then getting a tape deck to make tapes from CD