Running Maf And O2 Sensors On Single Turbo

[MJTru]

I just got me a Nissan R33 GTR. I Have Kyle from 6boost building me a manifold that’s a twin scroll T3 one. I’m planning on using a power FC (L-jetro) the manifold will have twin 38mm Tial waste gates and the turbo of choose is The GTX 3582r.

What I was wondering is how I will run the 2 MAF sensors and the 2 O2 oxygen sensors. For the MAF sensor I got a HKS divider pipe. This pipe goes from two MAF sensors to one collector, kind of like a y style fitting just much bigger.

Now how do I run the 2 oxygen sensors? Do I just weld the 2 bungs on the down pipe??

Or is there a way just to use one o2 sensor?

Thanks mate

[R31Nismoid]

If you can tune well enough you shouldnt need them.

I dont run them and have gotten 600-700km to a tank

Sounds like you already have the MAF sorted.

[MJTru]

If you can tune well enough you shouldnt need them.

I dont run them and have gotten 600-700km to a tank

Sounds like you already have the MAF sorted.

Yes i have the MAF sorted out, i'm using 2 30POO z32 MAF's. But i was just wondering if i tune the car and like you say don't use the o2's, wouldn't this make the car burn more gas at low loads. with the o2 turned off the car will run off the maps all the time (open loop) It wouldn't be able to be efficient?? It's all in the tune i guess.

In my head what your saying make sense, but I just cant get my head around it. At closed loop the car self adjust the fuel according to the inputs from the O2 sensors, and at some piont of WOT it goes to open loop and runs of the maps right? So in short my low end tune has to be good too. I would have to tune the whole map and not just the high loads points, But from low to medium and high spots.

Over the last five years i have really learnt how to tune all on my own with the help of SAU. If what i have mentioned is on the right track then i feel as if i can do it with somee time.

R31Nismoid whats the turbo set up your using to get the horse power goals. I'm looking at around the same power. Kyle from 6 boost mentioned to me that i should use a t3 split pulse manifold with twin 38mm tial gates, for the best response and power. He mentioned that i will get 20+ pounds of boost around 4500 rpms. I think that these numbers are with a fully build motor. I plan on building the motor myself, And my goals are about the same as yours.

Is there another parts of going single turbo i should know about??

Thanks Mate

[Hanaldo]

Yes i have the MAF sorted out, i'm using 2 30POO z32 MAF's. But i was just wondering if i tune the car and like you say don't use the o2's, wouldn't this make the car burn more gas at low loads. with the o2 turned off the car will run off the maps all the time (open loop) It wouldn't be able to be efficient?? It's all in the tune i guess.

In my head what your saying make sense, but I just cant get my head around it. At closed loop the car self adjust the fuel according to the inputs from the O2 sensors, and at some piont of WOT it goes to open loop and runs of the maps right? So in short my low end tune has to be good too. I would have to tune the whole map and not just the high loads points, But from low to medium and high spots.

Over the last five years i have really learnt how to tune all on my own with the help of SAU. If what i have mentioned is on the right track then i feel as if i can do it with somee time.

You're pretty much on the right track. With o2 feedback on, the ECU will target an AFR of 14.7. But you can get much better fuel economy by ditching them and setting up the cruise AFR's yourself. Mine are set to about 15.5:1 right now, could go a little bit leaner but I haven't got an EGT reading so don't want to push my luck.

[MJTru]

You're pretty much on the right track. With o2 feedback on, the ECU will target an AFR of 14.7. But you can get much better fuel economy by ditching them and setting up the cruise AFR's yourself. Mine are set to about 15.5:1 right now, could go a little bit leaner but I haven't got an EGT reading so don't want to push my luck.

Thats realy lean mate, The numbers i use are as follows

At max load i want about 12.2 knowing that at max load ten percent more fuel is the best for power and consumption as well as keeping the burn cool. I tend to use 12.2 or 12 for safety. Now at low loads i've always woundered whats the limit i can go and never went over 14.7. At medium lowed i use around 13. Now heres a good question. The egt gauge should tell you how hot things are getting. The next question is at what temp does the turbo and engine fail. That i dont real know I would guess around 900c.???? If i know that, then it would be fare to say i can lean it out untill i see a high EGT reading.???? Boy back to the tuning lessons. lol.

am i on the right track, keeping in mind that everyone that i talk to about tuning has there own ideas, and nothing seems to be solid stuff. I take it all in and reaserch the answers so all the answers really do help.

I agree that the ecu will target a afr of 14.7, but this is only at a certain point right?? ok so now that feed back is off and we are at high loads it will no longer target it to 14.7 but what i have in the maps right???

well thanks again mate.

[MJTru]

Can i tell the power Fc to target a differnt afr Like 15.5 rather than 14.7 ?????? or i have to tune the low to medium parts of the map????

[Hanaldo]

Can i tell the power Fc to target a differnt afr Like 15.5 rather than 14.7 ?????? or i have to tune the low to medium parts of the map????

You have to tune it, with o2 feedback on it will always target 14.7 because that's all the narrow band sensors are good for.

There is no danger running lean on low load as long as you keep the EGT's under control and the car isn't surging. But you have to make sure that your transient throttle enrichment is set up properly so that as soon as any throttle is applied the AFR's will jump back to an appropriate number. You will find a lot of people on here and other places will be running leaner AFR's than I am at cruise, I've seen as lean as 17:1.

Edited October 17, 2011 by Hanaldo

[MJTru]

You have to tune it, with o2 feedback on it will always target 14.7 because that's all the narrow band sensors are good for.

There is no danger running lean on low load as long as you keep the EGT's under control and the car isn't surging. But you have to make sure that your transient throttle enrichment is set up properly so that as soon as any throttle is applied the AFR's will jump back to an appropriate number. You will find a lot of people on here and other places will be running leaner AFR's than I am at cruise, I've seen as lean as 17:1.

I can remember seeing transient throttle in my heltech ps2000 but not in the power fc, i'll check again