watching

 

Paul any status on this yet?

 

I think Paul is still moving to NY. Be patient. ;)

 

Well, the last couple of days has been Scion central here at AEM.

Yesterday I confirmed the xB installation and played around with the O2 sensor spoofing. It's works well and you can now have the factory ECU perform it's closed loop tuning but to a differnt AFR value than stoich. The different target can be programmed based on engine RPM.

But, the best news is for you tC guys. I spend the afternoon with our 05 tC since I wanted to investigate the light load lean problems you guys have been plagued with. First off, the tC has a funky primary O2 sensor. It's kind of a hybrid current source sensor, not at all like the narrowband unit on the xB/xA or most every other car. It actually has more in common with a UEGO than an old narrowband. Of course, we designed and manufacture a truckload of UEGO current based O2 sensor kits so we naturally made the F/IC with the ability to bias current based sensors as well. I was eager to test it out.

In short, not only does it work, but it works much better than I could have hoped.

You will have a 21 RPM x 17 Boost table. In this table you put in a value representing the desired target AFR (it must be between 12:1 and 17.5:1). If the ECU is in feedback then the ECU will target on this value. If it is not in feedback then you use the traditional fuel map for adding fuel. I have been blasting the car all over town and am very, very pleased with the system. And remember, the ECU is being allowed to function in feedback as normal so the more you drive it the better it gets!

 

I just posted this on our forums but I figured it should go here also. Forgive the double post.

Custom O2 Feedback with the 05-06 Scion tC

Boosted Scion tC owners who want to enrichen the fueling at partial throttle settings when the factory ECU is in feedback mode can do so with the AEM F/IC. The factory ECU tries to run the engine at stoich (~14.7:1 Air/Fuel) when it is not at full throttle. However, forced induction tC's can make boost while still at partial throttle and the ECU is still in feedback mode. 14.7 is TOO LEAN to be running when under any appreciable boost and can cause stumbles.

The Scion tC has a uncommon O2 sensor style but the F/IC can still modify your target AFR's. First, it is assumed that you have the F/IC hooked up per the recommended connection diagram from AEM. It is also assumed that you have an independent AFR device to confirm the proper operation (It doesn't have to stay on the car but it is valuable during setup to confirm that everything is working OK).

Step 1:
Open the Setup dialog box
In the O2 sensor section (top right)
Load Input = MAP (Sets the Y axis of the O2 map to the internal MAP sensor)
Mode = Voltage (says the table will contain raw voltages)
Period = 250
Bank1 Hi voltage = 4.95
Bank1 Lo voltage = 0.0

Now open the O2 Map by either clicking on the icon with the big "O" in it or select "O2 Map" under the maps menu.

The O2 Map is a 21 RPM (X Axis) by 17 Boost (Y Axis) table. In each cell is the voltage you want for each operating point (The F/IC interpolates between the 4 nearest breakpoints for smooth transitions).

Set up the load axis by clicking on each breakpoint and setting it to whatever you want. You can also drag a bunch of them and it will interpolate between the end points. Do the same with the RPM. These two sets of breakpoints are unique to this table so changing them wont change them in other tables.

Enter the desired closed loop AFR target into the cells of the table using the following values.

AFR Value
17.4 = 4.0
17.0 = 3.9
16.6 = 3.8
16.2 = 3.7
15.8 = 3.6
15.5 = 3.5
15.2 = 3.4
14.9 = 3.3
14.7 = 3.2
14.4 = 3.1
14.2 = 3.0
14.0 = 2.9
13.8 = 2.8
13.6 = 2.7
13.5 = 2.6
13.3 = 2.5
13.2 = 2.4
13.1 = 2.3
13.0 = 2.2
12.9 = 2.1
12.8 = 2.0
12.7 = 1.9
12.6 = 1.8
12.5 = 1.7
12.4 = 1.5
12.3 = 1.4
12.2 = 1.3
12.1 = 1.2
12.0 = 1.1
11.9 = 1.0

So if you want 13:1 AFR in a particular point, put 2.2 in that point in the table. Some minor tweaking may be required but these values will get you VERY close. As long as the factory ECU is in feedback then these values will be used.

IMPORTANT:
If you just change the target AFR, the factory ECU will adjust the trims to achieve the desired AFR. BUT, if you make huge changes then you will get huge trim corrections and the chance of a check engine code for excessive trims. Dont forget to adjust the fuel maps to add the approximate amount you are requesting here. That way the trims will stay near zero!

 

so any prices yet?

 

wow, it looks real promising.

 

I'm certainly no expert, but isn't a 12:1 ratio a tad on the lean side? Or maybe not lean, but aggressive? I mean, it's no 14.7:1, but most of the AFRs I've seen around here are about 11.5:1. I know this isn't at WOT, but just curious about the system and possible problems.

Still looks kickass, though.

 

Remember, this is for partial throttle closed loop operation. 12:1 for 3-5 psi boost is plenty rich. Once you start running at WOT then you are open loop and can go to 10:1 if you want.

 

thanks for the update. I'm having my FIC installed and tuned on 6/26 and I will use the data you provided. thanks again

 

Is the PnP harness available yet from AEM for the tC unit? I'm going to have to pick one of these up!

 

It has been confirmed and is going into production. In addition to being available from AEM, they will be available from 3rd party vendors as well (Probably a heck of alot sooner than from us). We have already published the final hookup diagram for the 05-06 tC so any of them can make one right now. Or you can buy an extention harness from Boomslang, ASW etc... and hook it up yourself in a couple of hours.

 

can u use this piggyback to tune a treadstone kit ?

 

Ofcourse. Why would you NOT be able to?

 

just wondering dont beat me up lmao

 

LOL, sory bro, didn't mean to come accross like an ___. BTW, your screen name CRACKES me up!!!

 

I guess that's a no?

 

I am sure if you went to a good tuner that has dealt with AEM ems before then I am sure he or she would probably not be afraid to use this new unit, especially if he or she has tuned a tC before.

 

We're finishing up the harness right now and I will be testing the first unit in the states on my tC. We expect some very promising results.

(Yes I'd have the serial number to prove it haha)

 

Joe! i want one of these, and will be more then happy to be your guy's first customer for one! so hurry up and test it out!