Drive by wire problem!

Hey guys, lately I've been struggling with a problem with the drive by wire.

Some info:

Engine make: Toyota 1JZ GTE VVTI ETCSI

Stock ECU

The problem is that when I switch on the ignition, the throttle butterfly opens once and then the motor in the throttle body shuts off completly and I get no throttle input when I press the pedal. Once I switch off and on again, the same thing happens.

I have replaced the APP sensor and the TPS and it still doesn't work. So I have suspected that it could be the throttle motor/actuator. I have replaced that motor with a working throttle body motor and it still didn't work.

I have tested a working 2JZ throttle body and it works perfectly fine, I can hear the motor working and the butterfly opens with throttle input but the bolt pattern doesn't match with my intake manifold, so I can't use that.

So my question is, if I changed all the sensors on my 1jz throttle body, why doesn't it still work and a 2jz throttle body works?

If anyone could help me I truly appreciate it because I've been trying to fix this problem for months now.

Please ask if I left some info out!

Thanks

First thing I would do is test all the sensors, even if there are new they could still be bad.

Can you move the sensors over from the 2jz throttle body, or at least compare readings?

Are the pin outs the same? Check to make sure someone didn't modify your harness to use a 2jz throttle body. 
 

Any error codes?

In reply to No Time :

I have moved the motor and the TPS from the 2JZ throttle body the APP sensor doesn't fit with my 1JZ throttle body but I have purchased a brand new one and it still didn't work. The pinouts for the 3 connectors (TPS, APP, MOTOR) are all the same.

As for the harness it's not modified because the engine is swapped on a different car and the harness was purchased brand new and I have used the car successfully with this harness for over 2 years. I inspected it and it still looks new with no loose contacts.

In reply to Keith Tanner :

Yes, when I tested the first time I had this error code: P1128 - Throttle Control Motor Lock Malfunction

After words I replaced the APP sensor and the code was gone and it started showing a different code which is this one: P0120 - Throttle/Pedal Position Sensor/Switch 'A' Circuit 

In reply to Jvella36 :

Get your hands on a factory manual and look up the codes. They'll give you much more specific information than generic code definitions. 

In reply to Keith Tanner :

I will try that

Unplug the sensors and look at the mating (harness-side) connector, making sure that all contacts are unbent and free of corrosion.

Any chance the connectors are swapped? I know your car isn't a Honda, but Honda K-series drivetrains have a nice little "gotcha" in that the MAP and TAP sensor connectors are exactly the same and near each other, so it's easy to cross-connect them. To make sure you learn your lesson, Honda put the power on different pins, so you have the added bonus of blowing up the MAP sensor if you power it up that way even briefly. Ironically, the car will actually start and run that way, further confusing things... but I'm over that.

In reply to kb58 :

I have checked the harness side connectors, they look brand new (the harness is  like 2+ years old only). I have tried wiggling the wires a bit just incase one of them came loose but they are all tight.

I have checked if I mixed up the connectors but its impossible to mix them because they have different pinouts.

Do things work(for idle) with the throttle pedal assembly disconnected?  I'm wondering if the throttle itself is working as it should, and it's getting signal from the pedal assembly to go full?  Especially if this setup did work.

When someone says "test the sensors" I always take that to mean find what the appropriate voltage range is and test that. 

In reply to WonkoTheSane :

You have to press the throttle all the way for it work a bit, only the last bit of throttle works and it works badly like misfiring and by time if I try to drive it like that the throttle stops working all the way. I press on the pedal and nothing happens. As for idle I guess it holds it alright.

In reply to z31maniac :

I tested with a multimeter. The throttle motor got no power going through it only the first few seconds when I switch on the car then it cuts power.

What does the resistance measure through the two motors (1JZ and 2JZ)? 

Is there any continuity between motor pins and throttle bodies? 

Is the reading the same for the TPS when installed on the two throttle bodies? I.e. is the closed and open measurements the same on the 1JZ and 2JZ?  What is the spec?

Have you check to see if the throttle plates move freely without the motor installed? 

If you're testing the 1JZ mounted on the engine, you might want to try unbolting it and positioning it the same way you're testing the 2JZ to see if it's a weird grounding issue. 

In reply to No Time :

The resistance measure the same for both throttle body motors around 15 ohms and the motor also got a clutch in it and its resistance is around 4.8 ohms. 

I cannot perform any other tests because the 1JZ throttle body doesn't give me a chance to get readings since the motor and tps aren't getting any power. Even on with the scan tool it reads "Throttle Motor - OFF".

I have tried testing it unbolted as well incase there's a loose contact or something but still nothing.

It sounds like the ECM has some error check that's getting tripped and throwing that code, which also results in depowering the sensor.  I would guess some characteristic between your 1JZ and 2JZ throttle bodies is different.  How many pins on the throttle body motor itself?  Power, ground, drive voltage?  It could read the same impedance depowered and then have a short when powered, for example.  Then the ECU then sees this on the drive circuit and shuts it off.  

All drive by wire throttles have two throttle position sensors that the computer uses to cross check.  It sounds to me like when the computer does its throttle sweep self test, it sees a discrepancy and fails safe, meaning doesn't let the throttle work.

If the 2JZ throttle works, but not the 1JZ, it looks like they have different TPS strategies and it doesn't like one of them.  It'd be nice if everyone followed the Bosch way of having one sensor start at 4.5v and go down, the other start at .5v and go up, so that both sensor outputs always add up to 5v, but that isn't the world we live in  

I had a thought to wonder if you were using the BMW pedal or the Toyota pedal.  Without this information, part of me wonders if the swap wiring uses the BMW pedal but the BMW pedal is only electronically compatible with a 2JZ computer (two differing position sensors in the pedal, as well) and you actually have a 2JZ computer.

In reply to Kendall Frederick :

Yes it could be the ECU but it's weird that the other throttle body works fine. The motor have 4 pins (2 for the motor itself M+ M- and other 2 for the clutch C+ C-)

In reply to Pete. (l33t FS) :

I am using BMW pedal but its an E36 it didn't come with DBW.

Maybe I missed it, but has this car ran fine with the 1jz throttle body and just recently stopped?   
 

if so, then something broke/came loose.  If not, can you make the 2jz tb work?

In reply to jfryjfry :

The 1jz throttle body used to work fine until it slowly started acting up for example, rpm sticking to 2k then goes back to normal after a few seconds until it stopped working all together.

I could make the 2jz throttle body work but I would have to replace the intake manifold because it doesnt fit with the 1jz one but I would prefer to know what the issue is with the 1jz throttle body. I have replaced the sensors and still doesnt work.