Error code 8, advice??

[fkn16v]

Anyone had trouble with ae86 4age error code 8. Air inlet temp.

I have followed as the toyota books says but its all still the same.

Any thoughts. Checked nearly everything imaginable, timing, wires etc etc

[fkn16v]

Sorry double post

[jondee86]

1. Resistance of sensor approx 2000 Ohms @ 20 deg C (measured
at sensor with wires disconnected).
2. Resistance of sensor circuit with sensor connected, measured from
ECU end while disconnected from the ECU 2000-3000 Ohms @ 20 deg C.
3. Voltage across sensor circuit with everything connected and ignition
switched ON 2-2.8 volts.

These tests tell you that the sensor resistance is in range, the wiring
has continuity, and the ECU is applying the correct voltage to the sensor
circuit. In theory, if you obtain the correct values, you should not be
getting a no. 8 error code. If you are, then you may have to swap in a
known good ECU to see if the fault is in your ECU.

Cheers... jondee86

[fkn16v]

Thanks Jondee ill look into it.

[fkn16v]

jondee86 Wrote:1. Resistance of sensor approx 2000 Ohms @ 20 deg C (measured
at sensor with wires disconnected).

Just tested this and got 2000ohms

jondee86 Wrote:2. Resistance of sensor circuit with sensor connected, measured from
ECU end while disconnected from the ECU 2000-3000 Ohms @ 20 deg C.

Did this also and got 3000ohms

jondee86 Wrote:3. Voltage across sensor circuit with everything connected and ignition
switched ON 2-2.8 volts.

Also this and got 2.8volts.

Is this test n# 3 correct thou Jondee, Toyota 4age book says between THA and E2 with IGN ON there shouldnt be any voltage between these 2. Which leads me too belive that something inside the ecu isnt operating properly.

jondee86 Wrote:These tests tell you that the sensor resistance is in range, the wiring
has continuity, and the ECU is applying the correct voltage to the sensor
circuit. In theory, if you obtain the correct values, you should not be
getting a no. 8 error code. If you are, then you may have to swap in a
known good ECU to see if the fault is in your ECU.

Cheers... jondee86

http://www.toymods.net/TechDocs/4age_book/efi/fi_45.jpg

Number 1 test on there states No voltage, but i have 2.8 volts with IGN ON

So far all efforts point towards a new ecu.

[jondee86]

Nah... you have good results for the tests you have done. If you refer
to the top band on the page, you will see that No Voltage in the third test
is the Trouble condition, and that the STD Voltage is 2.0-2.8.

The tests on that page are checking the ECU power supply and ground
in case there is no voltage across THA and E2.

Fault code 8 indicates Open or Short Circuit in the air intake temp
sensor circuitry. First reset the ECU (disconnect battery and then put
your foot on the brake pedal). If the fault comes back, it might be a good
time to check that all your sensor plugs and wires are in good nick. A
bad/loose connector or wire rubbing on a sharp edge, might be causing
an intermittent fault.

Cheers... jondee86

[fkn16v]

jondee86 Wrote:Nah... you have good results for the tests you have done. If you refer
to the top band on the page, you will see that No Voltage in the third test
is the Trouble condition, and that the STD Voltage is 2.0-2.8.

The tests on that page are checking the ECU power supply and ground
in case there is no voltage across THA and E2.

Fault code 8 indicates Open or Short Circuit in the air intake temp
sensor circuitry. First reset the ECU (disconnect battery and then put
your foot on the brake pedal). If the fault comes back, it might be a good
time to check that all your sensor plugs and wires are in good nick. A
bad/loose connector or wire rubbing on a sharp edge, might be causing
an intermittent fault.

Cheers... jondee86

I really wasnt looking forward to stripping the loom apart to find the fault.

And when i try somethign new i always reset the ecu, poor thing has been reset about 8 times already

[fkn16v]

Well well well i bypassed the loom completly for the tha and e2 wires straight from sensor to ecu and now i have no error in ecu, still running rich

Before with error code number 4 plug was normal but the rest of the plugs were black. Now with wires bypassed all plugs are black and she's still rough.

Ill keep digging, maybe not ecu

[jondee86]

If its overfueling, probably pay to check your water temp sensor as
well. There are only a limited number of things outside of the ECU that
can cause your engine to run rich... water temp low, air temp low, bigger
injectors, high fuel pressure, air leak in the inlet manifold, variable
resistor or O2 sensor. Thats all I can think of Good luck !!

Cheers... jondee86