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2JZGE Na-T TT Ecu Mod

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Old 04-02-14, 09:20 PM   #1546
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Okay so I adjusted the TPS but it didnt work. I got the voltage on the yellow wire to read .68V with the key on engine off. It took longer for the surging to start (about 45 seconds) but it is still present. From start up, the idle will be high like normal (around 1000rpm) and then it will slowly drop to around 590rpm and then start surging. I don't know what else to do if my TPS is "in spec". Should I set it at .65v, or .70v? What else can cause surging idle, a few seconds after start up?
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1997 SC300 AUTO: NA-T, 6262 Driftmotion Turbo, TT ECU, Single 3" exhaust with muffler delete, Megan Coilovers, XXR 530's F: (18 x 8.75 +20) R: (18 x 9.75 +20)
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Old 04-02-14, 09:23 PM   #1547
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Quote:
Originally Posted by SCereal View Post
You have the TPS installed correctly? There's a trick to it as I recall. I think it's orient it clockwise past where the screw holes line up, put it on then turn it counter clockwise until you can screw it in, adjust from there. That way it catches on the tab in the correct orientation. there's a video on youtube about it.

Just a thought since you having trouble with it and I recall reading about it being tricky.
I haven't taken it all the way off to see if it was installed correctly, but I would assume the throttle would be really high if it were. I remember that when you put it back on , you have to rotate it so that the throttle is actually closed before you put the screws in.
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Old 04-02-14, 10:36 PM   #1548
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Default na-t tt ecu issues

I have a mk3 supra 2jz na-t. Did the tt ecu mod and after working out a few bugs it ran soooo good! It was still breaking tires loose well into 3rd 'auto' But I had some ebay intercooler couplers that messed up and leaked off my boost, got that fixed but now it doesn't run near like it did???? Checked codes and have o2 welded in bung yesterday, but haven't wired it in yet. ais code have one must be bad got it used, that's it except speed sencer. It only makes about 8 psi and kind of falls down ? sputters something under boost. Like not enough fuel or something? Still runs pretty good but nothing like it did at first, I want to go back there! Help please
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Old 04-03-14, 07:38 AM   #1549
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Originally Posted by BuffNStuff View Post
Is it 12v or 5v power into the resistor to the pin for the VSV?

*Found it. It is 12v power (PIN A31) to the 1kohm 1/2 watt resistor, into pin B40.*

I got both the EGR VSV and the IACV VSV wired up and those codes are gone!!

All that remains code-wise, are the 2 transmission codes, and the traction control code. THANK YOU.

I tried adjusting the TPS but I am scared. When I rotate it, it does change how the car idles. Either it will slow down or rev higher and faster. I am scared because it starts to go really lean after about 20 seconds of this surging. I dont really have enough time to fiddle with the TPS before I have to run and shut the car off.
Awesome, glad those codes went away easily. Is your MIL light even on now with just the trans codes or do you have to put the scanner on to notice?
You want it in the position where it slows down and will then try and idle low. sometimes so low that it can't keep the engine on, but that is the right position. IF it idles too low in this position, then you need to open up the butterfly valve some with the adjustment screw. It is best to set idle on a warm motor.

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Originally Posted by BuffNStuff View Post
Okay so I adjusted the TPS but it didnt work. I got the voltage on the yellow wire to read .68V with the key on engine off. It took longer for the surging to start (about 45 seconds) but it is still present. From start up, the idle will be high like normal (around 1000rpm) and then it will slowly drop to around 590rpm and then start surging. I don't know what else to do if my TPS is "in spec". Should I set it at .65v, or .70v? What else can cause surging idle, a few seconds after start up?
What do you mean by surging. your start up idle should be 1200 rpm's, and it should settle to 700 rpm. sometimes with this mod you do need to open the throttle body some more just because the GTE throttle body is a little larger in size, well that is my theory anyways. My car would idle at like 500 sometimes or so low it would shake and I thought it would turn off, so I cracked it open till it warm idles at 800 and now its perfect start up is 1200 and then it works down to 7-800 like stock. I did have to adjust the throttle body though. IF its too low and shaking its probably the same thing. If its hunting and swinging rpm's up and down like 4-500 rpm swings then that might be something else.

Quote:
Originally Posted by p00rbob View Post
I have a mk3 supra 2jz na-t. Did the tt ecu mod and after working out a few bugs it ran soooo good! It was still breaking tires loose well into 3rd 'auto' But I had some ebay intercooler couplers that messed up and leaked off my boost, got that fixed but now it doesn't run near like it did???? Checked codes and have o2 welded in bung yesterday, but haven't wired it in yet. ais code have one must be bad got it used, that's it except speed sencer. It only makes about 8 psi and kind of falls down ? sputters something under boost. Like not enough fuel or something? Still runs pretty good but nothing like it did at first, I want to go back there! Help please
The 02 needs to be wired in, I think you were lucky it was running so well without it. It needs it. Also what code do you have, AIT? you need to get one or a resistor to bypass it but I would get an actual one online I am using a generic aem one. you can also use a GM one.
speed sensor shouldn;'t have a huge impact on it unless its auto then I am not sure it will shift right. check your coil connectors maybe something came loose or you still have a boost leak you didn;t catch. check all the couplers, and only use T bolt clamps. you can use the other ones temporarily but they tend to break or work loose.
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Old 04-03-14, 10:36 AM   #1550
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Buff is your A/C working or did you need to relay it?
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Old 04-03-14, 11:50 AM   #1551
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Yea it is definitely surging. Rpms swinging up and down from 600 to 1300. I have not hooked up my A/C yet. Yes the CEL is still lit with the 2 transmission codes.

Scratch that, I didn't even look to see if my a/c already works. All the controls work and the screen for the climate control works. Air comes out of the vents, next start up I'll see if the compressor kicks on
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Old 04-03-14, 01:40 PM   #1552
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Okay so I made a discovery. The A/C works great. Exactly like it did on the stock ecu. Compressor kicks on and it's ice cold. While doing this, I noticed the car was not surging. I even pulled the car out of the garage and let it idle pull up and down the block, no surging idle even when stopped and in park. But as soon as I turned off the A/C, the idle dropped and the car stalled.

I am not sure how to diagnose this because usually, someone would have trouble with stalling when they turn the A/C ON not off. The only thing I can think of is that the surging is cause by the ECU thinking the A/C is on when it is not, so it idles up but it cant find the right rpm to stay steady at because there is no drag of the A/C. Then when I turn the A/C on it feels the drag from the compressor, and finds the correct rpm. Do you think this is possible? If so, I should be able to wire something up to make it realize when the A/C is off.

*Just a note* Transmission seems to be working just fine. Havent had a chance to drive over 5mph yet, but it seems to work. Just thought I would confirm that even with the CEL Transmission codes, it seems to shift fine.
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Old 04-03-14, 03:39 PM   #1553
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Okay so I went out and tried to set my base timing with the A/C on. Turns out that in order for it to idle without the surging up and down rpms, the A/C has to be on AND the transmission has to be in gear. If it is in Neutral or Park, the surging happens. I cant even set my timing because of this.
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Old 04-03-14, 04:40 PM   #1554
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I tried unplugging some sensors 1 at a time to see if the surging would stop. First I tried the TPS, but that didnt work. Next I tried the IACV and the surging stopped, but the idle skyrocketed. I dont know how high, probably 3000rpm. Could the IACV be my issue? I unplugged the IACV and took it off. It was dirty and had soot on the tip of it. I couldnt get the 3 screws out to look inside. Those screws are made of butter, and I am pretty sure they use lock-tite on them. I sprayed some throttle body cleaner on it and cleaned off what I could from the outside. put it back on and the car is still surging at idle. This is really frustrating.
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Old 04-03-14, 05:15 PM   #1555
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Default o2's

ive been looking all over this thread for o2 wiring all kinds of talk about it.... I want to wire 4 wire o2's with my jdm tt ecu. my car is running so rich it is having miner explosions in exhast. thanks Never mind I found it. in case anyone else needs it....blue is signal goes to pin 48 on 80 pin, white is ground, the two blacks are for the heater. one is switched 12v, the other goes to pin 71 the ecu controls heat circuit by switching the ground.

Last edited by p00rbob; 04-04-14 at 12:05 AM.. Reason: found answer to question was asking
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Old 04-04-14, 11:21 AM   #1556
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Did you get your sensors wired up? Did that fix your issue?
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Old 04-04-14, 11:42 AM   #1557
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Its good news that its working right in gear with the a/c on, that means its probably just an adjustment most likely on the throttle body. you are using the stock throttle body and intake right?

When you hit the a/c button as far as the ecu is concerned it just increases the IACV valve duty a few %, as in it cracks it open a little more.
If its settling down the idle in gear and not hunting, but hunting with no load or skyrocketing when you disconnect the idle valve, my only thought would be that your throttle body may be cracked open too much because its hard to have enough air to support 3k rpm even when warm and the idle valve is fully open. So if you get too much air in the system and it cannot idle down to a range with the IACV, the stock ecu may try and do advanced things like swing the timing to get in range, except its not very good at it when its so far out.

can you tell me when you first start the car what rpm's it is at? is it above 1400rpm's?

I am gonna PM you my number next time you are working on it let me know and I will try and help out, you are so close its unreal. sometimes its just the tps connector or something is cracked also, but I have noticed there is a need to make small adjustments to the warm idle when doing the tt ecu mod because of the difference in throttle body size and I think each ecu has slightly different parameters.
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Old 04-04-14, 11:58 AM   #1558
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Messing with the IACV effected change so that seems significant to me. Testing procedures are as follows:

resistance between B1-S1 and S3, B2-S2 and S4 should be between 10 and 30 ohms according to the manual.

you should also hear a clicking sound immediately after stopping the engine.

apply battery voltage to terminals B1 and B2 and repeatedly ground S1-S2-S3-S4-S1 in sequence and observe that the valve moves to the closed position.

apply battery voltage to B1 & B2 and reverse the sequence and see that it opens.


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I tried unplugging some sensors 1 at a time to see if the surging would stop. First I tried the TPS, but that didnt work. Next I tried the IACV and the surging stopped, but the idle skyrocketed. I dont know how high, probably 3000rpm. Could the IACV be my issue? I unplugged the IACV and took it off. It was dirty and had soot on the tip of it. I couldnt get the 3 screws out to look inside. Those screws are made of butter, and I am pretty sure they use lock-tite on them. I sprayed some throttle body cleaner on it and cleaned off what I could from the outside. put it back on and the car is still surging at idle. This is really frustrating.
Ali makes a good point too, 3k rpm i dont think is possible with the throttle blade fully closed.
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Old 04-05-14, 07:35 PM   #1559
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I will play with the idle screw on the throttle body and see if it makes a difference. I'll also note the rpms on cold start up. Maybe I'll also try messing with the tps some more, as that also had SOME effect on the surging. (Either slowing it down and smaller range or rpm, or higher reving. This will have to wait till Monday because I have a company event tomorrow in PHX.
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Old 04-06-14, 04:20 PM   #1560
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great let us know how it goes, the slowing it down and smaller range or rpm is the correct tps position, and then if its too low increase idle via the throttle body.
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