Gen 6 FCD + Extra's for the SW20 Turbo

[Tronic]

The FCD I developed a year or so has evolved to a final product that I will try and squeeze into a single box solution if there is any interest.

Fuel Cut Defender - Now has exactly the same Voltage from the Turbo pressure sensor to the ECU right up until just before fuel cut then it's clamped constant to prevent cut. This is better than any commercial product that made it to market.

Boost activated fan switch - Kicks in you IC fan at 5psi and runs until your off boost on a "timer". The higher the peak boost the longer it runs after you stop boosting.Works independantly to the engine bay temp sensor.

Boost activated Fuel Pump switch - Kicks in you fuel pump relay and bypasses the fuel pump resistor pack at 10 psi. Gives you another 4 to 5psi of fuel pressure to give you safer fueling to 15-17psi of boost. The AFR on mine at 15psi is now down to 11.9:1 with this feature.

Install is power and cutting two wires and splicing into two wires all in the area of the ECU in the boot. 8 wires total, it could not be easier. Connector design will allow conversion back to stock in under 30 seconds if required for fault finding/testing or if the unit is removed.

Shame I didn't finish developing it 10 years ago.

[freebird]

Sounds good, are you going to be selling these and if so what price?

[Malcolm]

Not trying to be a hater, but I have a couple of questions:

Fuel Cut Defender - Now has exactly the same Voltage from the Turbo pressure sensor to the ECU right up until just before fuel cut then it's clamped constant to prevent cut. This is better than any commercial product that made it to market.

Isn't this what a zener diode FCD does? Or is there a voltage drop across the zener that you have eliminated with yours?

Boost activated Fuel Pump switch - Kicks in you fuel pump relay and bypasses the fuel pump resistor pack at 10 psi. Gives you another 4 to 5psi of fuel pressure to give you safer fueling to 15-17psi of boost. The AFR on mine at 15psi is now down to 11.9:1 with this feature.

Isn't this how the standard system is supposed to work?

[Tronic]

Tried the zener diode mod at the beginning. It didn't work for me. Some aditional circuitry was required. Nothing too complicated, just basic electronics but like many things it took a while to perfect. The ideal solution is to have the same Voltage from the Turbo pressure sensor getting to the ECU until just before fuel cut and then have it clamp or flatline to prevent cut.

No the fuel pump relay only works to give you more fuel pressure (about 4psi extra) on a cold start for about 6 seconds, after that it's always off and the resistor pack cuts the Voltage to the Pump to about 10.5V. The flow rate of the fuel pump is HIGHLY dependant on the supply voltage. By turning the relay on again at the maximum stock boost the fuel mixture is made richer. It is easy to check the voltage to the pump at the FP+ in the diagnotic box. When I finally have to replace the pump I will be also adding a thicker wire from the relay to the pump connector and also double the wires in the tank. This would be good for another 1 or 2psi and you want to be at the maximum fuel pressure spec when new as it will only decrease with age.

[Malcolm]

No the fuel pump relay only works to give you more fuel pressure (about 4psi extra) on a cold start for about 6 seconds, after that it's always off

This is contrary to what I've read about the operating of the fuel pump relay since I got my first 3sgte powered car 10 years ago. Do you have anything to back it up? I've never bothered to monitor the behaviour of it before (and in my car there is no resistor anyway).

I don't get why the zener diode mod didn't work for you, it did for me on my Celica but now I just run the MAP sensor with no boost line attached (no good if you want the stock gauge to work, but otherwise the easiest way to boostcut freedom)

[vvega]

same here malcom .. also i found my fuel pump voltage changed Dependant on load
how ever he is right .. it does give full voltage for a few seconds on startup ... found this out when i forgot to plug in my resister pack ... the car would die after a 6 seconds ... but would continue to run if you jabbed the throttle lots

also the zener diode trick does exactly what you claim yours to do ... meh i dunno .. just pull the hose .. most successful method ever

[freebird]

Which hose are you guys talking about and what effect does it have, should the disconected ends be blankes off?

[vvega]

the hose that connects to the map/pressure sensor .. and yes you block the end of this hose
so basically .. pull it off the sensor then block the hose were the sensor nipple would normally go in
this has 2 effects
one .. your factory boost guauge will no longer fuction .. and 2 .... you will no longer have a boost cut of any kind ...
remebering that to much boost will kill your engine

[Benckj]

remebering that to much boost will kill your engine

Most important point. By disabling some of these features you remove protection which was designed to save your engine in the event something goes wrong.

[vvega]

lol way to much facebook benckj .. i just went to like your post

[Tronic]

No the fuel pump relay only works to give you more fuel pressure (about 4psi extra) on a cold start for about 6 seconds, after that it's always off

This is contrary to what I've read about the operating of the fuel pump relay since I got my first 3sgte powered car 10 years ago. Do you have anything to back it up? I've never bothered to monitor the behaviour of it before (and in my car there is no resistor anyway).

I don't get why the zener diode mod didn't work for you, it did for me on my Celica but now I just run the MAP sensor with no boost line attached (no good if you want the stock gauge to work, but otherwise the easiest way to boostcut freedom)

Yes a voltmeter in the FP+ of your diagnostic box when you first start your car and a fuel pressure gauge. I'm really not sure why Toyota went to all the added expense of the resistor pack and relay, perhaps someone else here can explain the logic behind it.

Well there is working and there is working when it comes to the actual electronics. Did you monitor the voltage for the TPS to the ECU after you fitted the Zener ? probably not because you had fuel cut you thought it was working, however you no longer had a Voltage that ramped up from 1.67 V at idle all the way up to 4.2V and then flatlined the way it should if you want to acheive a FCD function.

More boost is great, as long as there is the extra fuel to go with it. Sure the stock fueling is rich at 10 psi but you find out very quickly it is no longer rich at 15 psi. Obviously another 4 psi of fuel pressure from 10psi onwards is of assistance to keep it on the rich side. Yes you can argue it's crude, but hey it's a stock ECU without the luxury of playing with the fuel map but it still beats your engine going bang.

Also if you keep the stock IC, Which IMO is perfectly good for up to 200Kw if you upgrade the fan on it and run the fan while under boost you end up with some intelligent electronics that saves you a whole pile of money on things you don't need to get some pretty good dollars per Hp gain.

I'm not going to get into an argument about the why's and why nots of the other methods of acheiving fuel cut other than to say that because it appears to be working doesn't mean it's working as it was intended to work, after all its your car so do what you want with it.

This project has always been aimed at those on a budget wanting to get the easy to get initial Hp gains and because I get a great deal of personal satisfaction out of design & build both electrical & mechanical. Anyone can give their car to someone else along with a pile of money and say build me a beast, but there is no challenge in that for me, the challenge has always been to find the most power I can get out of a stock appearing car while doing all ther work myself with $2000 to spend.

This FCD is just one of the the results of the challenge.

[vvega]

sorry tronic but my dyno testing of mr2's dose not follow what your saying

[Tronic]

sorry tronic but my dyno testing of mr2's dose not follow what your saying

Yes well I suppose I'm a bit of a perfectionist. The idea is to maintain the integrity of the signal from the Turbo Pressure sensor as much as possible while still acheiving the FCD function.

So you did a side by side comparison on a dyno of all the ignition and fuel mapping ? or was it just power ? The Dyno is about as useful as a flamethrower to light the candles on a birthday cake when it comes to working out small changes in power.

Sorry I will always maintain the Turbo Pressure sensor does more than just drive the crappy stock boost guage and to derive the point of fuel cut because of the characteristics of the output signal from it.

[vvega]

injector duty, fuel pressure /flow .. ignition curve egt's and afr's

and your right .. but after 20 runs .. statistically there was nothing that showed there was a different pattern

my testing showed the fpr relay clicking over at about 15% duration to deliver full voltage

there was a reason i invested so much money in pico testing and logging gear .... i like to be 100% on the money

[Tronic]

injector duty, fuel pressure /flow .. ignition curve egt's and afr's

and your right .. but after 20 runs .. statistically there was nothing that showed there was a different pattern

my testing showed the fpr relay clicking over at about 15% duration to deliver full voltage

there was a reason i invested so much money in pico testing and logging gear .... i like to be 100% on the money

I stand corrected the fpr kicks over at between 1 or 2 psi of boost on a test drive I just did.

That simplifies the design somewhat with less to get in the box.