AFM 4AGE & oxygen sensor

wewerica
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AFM 4AGE & oxygen sensor

Postby wewerica » Sun Jan 17, 2016 2:22 am

Hello everyone,
I have trouble with my car. Its ae92 4AGE AFM bigport.
When I disconnect oxygen sensor i have the problem with power inside my car.
1. So my oxygen sensor is disconnected, ingnition switch is in OFF position car has power..
2. Oxygen switch disconnected, ignition switch is in ON position car does not have power and obviously it won't start...
3. Connect oxygen sensor and everything is back as it shoud be.
Any clues?

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Re: AFM 4AGE & oxygen sensor

Postby yoshimitsuspeed » Sun Jan 17, 2016 9:38 am

Why are you disconnecting your oxygen sensor? Were you trying to troubleshoot another problem? If so what was it?

What do you mean Oxygen switch?

wewerica
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Re: AFM 4AGE & oxygen sensor

Postby wewerica » Sun Jan 17, 2016 10:39 am

Im disconnecting oxygen sensor because I wont to install DIYPNP and LC-1 wideband.
I ment oxygen sensor sorry :(

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Re: AFM 4AGE & oxygen sensor

Postby wewerica » Mon Jan 18, 2016 3:12 am

What are those two pins for on AFM ECU?
HT & OX?
How they work?

When I remove O2 sensor, my car won't start..

http://postimg.org/image/5vgbydky7/

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Re: AFM 4AGE & oxygen sensor

Postby yoshimitsuspeed » Mon Jan 18, 2016 9:36 am

OX is the signal wire coming from the sensor to the ECU. It is the 0-1v signal that tells the ECU the AFRs.
HT is the heater curcuit. +b should actually be the hot side of the circuit and HT should be ground that the ECU switches on and off to control the temp of the sensor.
None of this should have anything to do with the rest of the power in your car.

Here is one place to start.
With the O2 sensor plugged in and the key on check +B for voltage at the check connector. Then unhook the O2 sensor and check for voltage again.

Aside from that I think you are going to be best off taking this from the other end and trying to figure out where your power stops with it unhooked. Basically just troubleshooting the system as you would if you hadn't made the correlation of the O2 sensor. So finding out where the power is and where the power stops when you turn the key on.
Since the only online wiring diagram I know of sucks real bad I am trying to make it more useable. I'll have it done and post back in a little bit here.

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Re: AFM 4AGE & oxygen sensor

Postby wewerica » Mon Jan 18, 2016 10:49 am

Better quality image. AFM pinout and wiring diagram.
LINK

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Re: AFM 4AGE & oxygen sensor

Postby yoshimitsuspeed » Mon Jan 18, 2016 11:27 am

Okay here is a diagram that has been tied back together better than any other digital ones I have seen. It is an AW11 diagram so there may be some small differences. Hopefully you have diagrams for your chassis.
But this will allow us to discuss the general idea.
http://www.matrixgarage.com/pictures/19 ... iagram.png

First off make sure you have power at your AM1 and AM2 fuses. Then move to your ignition. Make sure there is constant power at AM1 and AM2 where they go in to the ignition.
Then turn the key on and make sure there is power coming out of ACC, IG1 and IG2.
From here you just want to start chasing power downstream. If you have no power to the dash or anything else then figure out how far power goes in the circuits and figure out where it stops.
If the car won't crank then figure out if you have power on the ST2 circuit when you turn the key all the way to the start position. If so then see if you have power at the starter, both the signal wire coming from ST2 and on the big power wire coming from the battery.
Check all your grounds. Whenever you have strange behaviors more often than not it's ground related. Maybe your motor doesn't have any good grounds and maybe somehow the O2 circuit was providing an alternate ground.

Other than that just start chasing circuits and figure out where the power stops or where you aren't getting ground.

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Re: AFM 4AGE & oxygen sensor

Postby wewerica » Sun Jan 24, 2016 1:46 am

my friend have found the problem :)
the problem was ECU grounding, 3 pins on ECU are GND but none of them where connected to -
So the only GND pin on ECU was O2 GND, and when I disconnect O2 sensor I cannot start the car because it does not close the circuit...

Temporary we've grounded ECU so I can drive car, when I get some spare time I will check GND connections with the ECU.

Thanks everyone for help

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Re: AFM 4AGE & oxygen sensor

Postby jondee86 » Sun Jan 24, 2016 6:59 pm

Sounds as if these little blokes didn't get bolted down...

Image

They get clamped under one of the fixing bolts for the plastic duct that carries
the wiring harness on the intake side of the engine. The above picture shows
where it hides on an AE92, and it is easy to miss if you have had the harness off
the engine.

Image

On an AE86 the wires will come out of the taped up harness at the rear of the
head on the intake side as shown above.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

wewerica
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Re: AFM 4AGE & oxygen sensor

Postby wewerica » Sun Jan 24, 2016 10:30 pm

@jondee86 how did you know? :D
you're 100000% right. this little **** wasnt bolted to the intake manifold...
after engine rebuild I've replaced bigport head and intake with smallport and on this spot where bigport had screw smallport doesnt.
Found it yesterday and bolted. :D

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Re: AFM 4AGE & oxygen sensor

Postby yoshimitsuspeed » Mon Jan 25, 2016 9:17 am

Glad you found at least part of the issue but I would go through the system and make sure everything else is good. I wouldn't expect those grounds to cut power to the rest of the car which makes me think you may have other grounds missing or with poor connections.
Make sure you have good primary grounds between your batt, chassis and motor with good clean solid connections.
I like to have two large straps from the motor to the chassis just for a little redundancy. Then you will have your smaller ones as Jondee pointed out above. On the AW11 there is also another that goes from the strut tower to the intake mani but not sure if it has an equivalent on the longi cars though. If you don't have big primary grounds though then when you try to start the car the circuit will try to find the next easiest route and that can be one of these smaller grounds, the throttle cable, the most recent I saw was a steel braided brake line. That confused the heck out of the guy. Any of these things can melt, burn or even catch on fire so you really want to make sure you have sufficient grounding.