Scion tC Forums banner
1 - 20 of 73 Posts

·
Registered
Joined
·
57 Posts
Discussion Starter · #1 ·
My Apexi S-AFCII has been on my tC for about 2 months. The installation went good and all the readings are correct.
Now, the problem i get is when i try to tune the thing. I will tune it and then after driving i will turn off the car. Later i will come back and start the car and at idle i am at 2000 rpm, the check engine light will appear and then the rpms drop to 400. When i drive the car the car shifts into second gear and at 2000 rpm the revs drop to 0 and the car dies. I don't know what the problem is. I have tuned AFCII before and nothing has been wrong. I have done many tunes on the tC and other people have done then on my car too. But, the problem seems to keep coming back. I was hoping someone could help me out, the more help the etter.....Thanks
 

·
Registered
Joined
·
1,866 Posts
Well from what I have been reading our ECUs correct whatever you do to them so if you try and tune it, the ECU compensates per se and tries to change it back...I think thats right in some round about way

Where is lo bux?
 

·
Former '05er
Joined
·
12,467 Posts
You can't make permanent changes to closed loop operation on a Toyota. It won't stick. TCCS uses feedback from the a/f sensor and will change the correction factor to reset everything you did. It's been like this pretty much forever with Toyotas, I first learned about it with MkIV Supras.
 

·
Former '05er
Joined
·
12,467 Posts
Does it use throttle position input? If it does, you can set a/f when throttle position is over 75% and it will work. I'm still not familiar enough with how the tC ECM works be absolutely certain, but this is what works for Supras.
 

·
Registered
Joined
·
11,881 Posts
Off the top of my head, tC ECU goes into open loop above 4000 RPMs.
 

·
Former '05er
Joined
·
12,467 Posts
I bet it doesn't at less than 75% throttle. I bet alot it doesn't.
 

·
Registered
Joined
·
57 Posts
Discussion Starter · #8 ·
Yes it uses a throttle position input . Later today i am going to check the codes and see what the code is saying is wrong. Then maybe i can figure out something. If you guys have any more ideas i will give them a try and see if they work and let you guys know. Thanks for the help.
 

·
Registered
Joined
·
57 Posts
Discussion Starter · #9 ·
Just got back for Auto Zone. The CEL was off when the guy came to check it but we were still able to get the code. The code is P0103 and the wording at the bottom is Maf-Vaf Low Input. The guy thinks it is a miss fire. What do you guys think it is? Could he be right, if he is how did an AFCII cause it? Also, what can i do to fix the problem?
 

·
Registered
Joined
·
11,881 Posts
Originally posted by fairladyz541@Nov 14 2005, 07:44 AM
Just got back for Auto Zone. The CEL was off when the guy came to check it but we were still able to get the code. The code is P0103 and the wording at the bottom is Maf-Vaf Low Input. The guy thinks it is a miss fire. What do you guys think it is? Could he be right, if he is how did an AFCII cause it? Also, what can i do to fix the problem?
According to the service manual:
P0103: Mass or Volume Air Flow Circuit High Input

Info: When any of these trouble codes are set the ECU enters fail-safe mode. During fail-safe mode, the ignition timing is calculated by the ECU according to the RPM and throttle valve position. Fail-safe mode continues until a pass condition is detected.

Trouble Areas: Short in MAF meter circuit, MAF meter, ECU.

Diagnostic Help: Check the air-flow rate by monitoring the MAF signal through the ODBII scan tool.

Value Malfunction
~0.0 Open in MAF power source, Open or short in VG circuit
~271+ Open in EVG circuit

P0103 is set when the MAF meter voltage is greater than 4.9V. Operating range is between 0.4V to 2.2V.

Going by my experience from the e-Manage Ultimate... there is either an error with your tuning via the SAFCII or a wiring issue. You can look at pg 05-91 in the service manual for a more detailed explanation, all of my information was ganked from this.
 

·
Former '05er
Joined
·
12,467 Posts
I agree 100%. Faulty wiring, or bad SAFC programming. Keep in mind the ECM expects certain values for certain operating parameters, and this ECM is a 32 bit device. It can do data sanity checks and not run out of processing power.
 

·
Registered
Joined
·
57 Posts
Discussion Starter · #12 ·
Is there anyone who has installed a SAFCII on a tC yet. If so, what wiring diagram did you use to connect the SAFCII. Looking to see if my wiring is right. If anyone has a diagram for me to check with that would be great, or if anyone has tuned one and they can help me with my tuning.
 

·
Registered
Joined
·
11,881 Posts
If you were misfiring... you'd know. Trust me. I had a misfire when I installed the e-Manage Ultimate. First thing was the car idled like complete <insert explitive here>, secondly... when you floored it... it'd barely move. I'm talking it'd be like a normal car trying to start in 4th gear. SSSLLLOOOWWWW. Also, misfire would throw codes P0351-P0354
 

·
Registered
Joined
·
11,881 Posts
Originally posted by fairladyz541@Nov 15 2005, 07:30 AM
Ok Thanks....So, what should I do know.....
Lots of things... could you PM me your AIM or MSN so that I can talk to you on there? I'll see what I can figure out.
 

·
Registered
Joined
·
179 Posts
If im not mistaken, WOT for the TC is above 63% TPS. So, set the hi/lo at 64/65% or something higher like 74/74%, and also try resetting the thing, it may have some settings you aren;t aware of. An SAFC2 is stupid easy to use, so triple check that wiring, you may have crossed the maf and tps wires or something.
Besides that, just try figuring out what is wrong by process of elim.
 

·
Registered
Joined
·
57 Posts
Discussion Starter · #18 ·
So today I tried to tune the AFC II again but the problem happen again. Now, I think its time to look for a shop. My shop cant figure out what to do so if anyone knows a place that can do it in the Indiana area let me know. Or if anyone has another solution for me.
 

·
Registered
Joined
·
57 Posts
Discussion Starter · #20 ·
GOT IT!!!!! Oh man does it feel good. I got the SAFC II to work on the tC and man does it help. The car now has some power. I love it.......I will tell you guys everything I did only if you guys want. I would go to the dyno but it snowed over a foot here in Illinois so i want to stay inside today. Let me know if anyone wants to know what I did or any other information.
 
1 - 20 of 73 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top