Knock sensor unit location

[Turbone]

Well, my FSM says its in the instrument panel

Has anyone ever come across it?

For EA82T's only.

[idosubaru]

Knock sensor for EA82T?

 

threaded into the top of the block towards the rear, near the bellhousing mating area. it will be threaded into the block with a wiring harness plugged into it. i believe they lean more towards the passengers side if i have to take a guess but are close to center.

[idosubaru]

what year/vehicle, i think some EA82T's don't have a knock sensor.

 

if you're familiar with the knock sensor on XT6's or any EJ engine, they're all about the same location.

[Turbone]

Gary, its the knock sensor unit. Its the brain or control unit for the knock sensor.

[ausubaru92]

On 3 Plug ECU, 1985/86/87.5, Flapper stlye AFM EA82T's there is a knock control unit that is mounted in the left hand front guard. The knock sensor has 2 wires that go to the unit in the guard, along with wires from the distributor and coil.

 

On 4 Plug ECU, 1987.5+, Hotwire style AFM EA82T's the Knock control unit is built into the ECU. The knock sensor has only one wire and goes straight to the ECU

[Turbone]

On 3 Plug ECU, 1985/86/87.5, Flapper stlye AFM EA82T's there is a knock control unit that is mounted in the left hand front guard. The knock sensor has 2 wires that go to the unit in the guard, along with wires from the distributor and coil.

 

On 4 Plug ECU, 1987.5+, Hotwire style AFM EA82T's the Knock control unit is built into the ECU. The knock sensor has only one wire and goes straight to the ECU

 

Thanks, I was afraid of that :-\

I have a 89.5 and have never seen anything inside the dash that looked like a control unit, except for the ECU.

If I'm going to be upgrading my injectors, I probably need to get another ECU. I'm running rich, even at idle. I've replaced the knock sensor twice and still get a knock code.

[Gloyale]

Gary, its the knock sensor unit. Its the brain or control unit for the knock sensor.

 

It's only on the flapper system cars. Later models it's built into the ECU.

 

On the early ones, the unit is attached to the far end of the dash, behind glovebox on the passenger side. You almost have to unbolt that side of the dash and pull it forward to access.

[idosubaru]

I've replaced the knock sensor twice and still get a knock code.

maybe you could check the wiring or clean the threads in the block with a tap?

before going to any trouble i'd wrap the threads of the sensor with about 10-20 wraps of plumbing tape. taking care to wrap in the proper direction so it doesn't come off as you thread it back into it's place.

[Cougar]

Turbone,

 

Have you checked to see it the coolant sensor for the ECU is working ok? This may explain the running rich trouble.

 

For the knock sensor trouble, have you checked the wire connection resistance between the sensor and the ECU to make sure it is ok? The sensor itself may read about 500,000 ohms referenced to ground.

[Turbone]

Wouldnt I get a code if the coolant sensor wasnt working right?

But thats fairly new also.

I have about 15K on this engine and I have alot of new sensors on it.

I havent checked resistance yet on the knock sensor.

But the ECU is original, from 89. I have another available and might try a quick swap.

[Cougar]

You will not get a code if the resistance of the sensor is within limits. Some folks have had problems with the sensor showing the engine is always cold so it runs rich. You can see if the voltage changes across the sensor as the engine warms up. That is one way to check it. If you don't see much change in voltage as the engine wams up then the sensor isn't working correctly.

[presslab]

Thanks, I was afraid of that :-\

I have a 89.5 and have never seen anything inside the dash that looked like a control unit, except for the ECU.

If I'm going to be upgrading my injectors, I probably need to get another ECU. I'm running rich, even at idle. I've replaced the knock sensor twice and still get a knock code.

 

Yes, the knock wire goes to the ECU.

 

I too had a knock code on my 88 turbo. It turned out to be the wire in the engine harness! Check it for continuity and short to ground. I ran another one and that fixed the code.

 

On the subject of knock sensors, mine was false triggering at high RPM, probably due to my 150k mile engine. I put a 470k resistor in series with the signal wire to desensitize it. It's been working great.

 

I upgraded my injectors (280ZXT) with a simple mod to the MAF and a relay for the O2 sensor in my "Turbo o2 sensor" thread.