Closed loop tuning with SMT6


New Member
Here are the relevant pages from the SMT6 application notes regarding closed loop tuning. Has anyone had any experience with setting this up? Toys, Weasy you guys have played with the SMT6 haven't you?


New Member
I did some more research and found that the SMT6 can either alter the airflow signal OR it can alter the O2 output but not both in the same unit - 2 units would be required so it's a no-go.

The SMT7 however can alter both if that's compatible with the 1UZ.


Ya, On this v6 it has 2 lambda o2 sensors. I just disconnected the rear bank o2 sensor & fed the front bank signal to both of my ECU inputs.
On an N/A engine I'd feel different, but on mine, I got to where I liked running:
Lambda - analog
Extra injector - fueling
Ignition timing
Having the lambda o2 slide way lean at the onset of boost is priceless AFA smoothe transition into boost goes - where the ECU would normally be in closed loop. No-retuning - ever
Which just goes onto of the fact that the extra injector makes the ECU happier because it's easier to dial in so the ECU won't freak out (not to mention tune & setup than larger injectors) when you ask for a lot of fuel in what would normally be closed loop. (i.e. a turbo will always come on boost long before the car get's out of closed-loop, so you're fighting fuel trim & factory programming every time you hit boost.)

Compaired to just tuning the AFM... It's superior when you've got extra injector<s> to make-up any big missing fuel. I think far superior. I never missed tuning the AFM on mine, after I went from tuning the AFM to tuning the lambda signal.

You can also take the triggerable output & run that to a relay to flip the TPS's actual signal (VTA) going to the ECU, to the (VC) i.e. the power supply for the TPS & air meters. This accomplishes sending the ECU the maximum allowed voltage for the tps. - Why is that handy to do?
Because most Toyota ECU's wait for 75-80% open throttle (VTA) before going open-loop. Trigger the relay off a MAP, or boost pressure switch as soon as you get into boost - You'll get open-loop earlier & have an easier time getting a great tune that won't be fighting the ECU every time you have boost in closed loop.


New Member
Thanks! Rob (uzz32soarer) is having problems with the closed loop tuning with his C's supercharger kit so the switch to open loop would probably be the way to go.


New Member
Apparently the SMT7 has more tables so you can tune closed loop and open loop in the 1 unit however it has a totally different setup and may not be compatible with the 1UZ... best to email Perfect Power for a full run down.


The smt6 has:
1 analog/frequency output (For changing a voltage, or frequency based signal. i.e. a narrowband o2 sensor / maf/afm/map sensor, or like a speed sensor)
1 driver circuit (For driving injector<s>, or a pulsed solenoid, i.e. n2o, or say a vvt oil pressure solenoid, or a boost solenoid)
1 ignition frequency hicky, for changing a few different types of ignition signals, OR driving a coil directly.
1 triggerable ouput (actually input, it's a switchable ground, triggered by various things) for tripping a relay (which can turn on/off whatever you wanted)

the smt7 has all of that, plus a second analog/frequency ouput
It can also map the analog/frequency outputs to help tuning - useful in doing a MAF to MAP swap...
more inputs
you can hook it to a wideband & have it help you figure out what changes you need to make to get the engine to do what it wants. (Or a narrow band if that'll suit what you're trying to do)
It has more inputs to scale your tuning too
A way to add more types of ignition pickups
3 triggerable outputs

That's just what I know off the top of my head. They both:
Can log all data when connected
Live tune (Blah FTC's suck! LoL! What annoying little things!)
Have switchable maps
Have more than just 2 tuning paramiters (I.E. the common RPM * TPS table - which is *very* useful once you actually start using them)

They're just neat little things.

*the* signle absolute best thing I can tell you to do. Is download the smt6 software, and download the smt7 software.
Register here and download.

There is alot you can do with them. Especially that smt7. It's just crazy.


New Member
Thanks fellas, so the SMT7 simply has a few more functions then the SMT6, but both are good units....that is my take....


New Member
I really appreciate the fact that you can advance or retard the timing with these units, unlike the Apexi piggy back ECU I am running now that only does the A/F ratio tuning....

Outstanding breakdown and write up Toysreme, you are the man...........


New Member
Hi, are you guys running stock transmission? Is it possible to ground or open the o2 sensors via relays or transistors to force open loop so as to keep normal load signal for desired transmission shift pattern and transmission line pressure. I know this would log codes but if all else works it would not worry me.
My SMT6 was supplied by Bullet without MAP sensor, AFM and RPM signals are currently modified depending on TPS load input. Any ideas would be great so I can finally get dyno tune done.


New Member
If you change the load input from TPS to MAP the easiest way to force it into open loop would be to flick the TPS to wide open throttle.

It's been a while since I used the SMT6 but I'm sure you could use one of the output wires to do the job when it comes on boost.


New Member
Sorry to bump this extremely old post, but are these tuners around anymore. I have a few questions about Perfect Power setups. Especially the Lambda tuning :)