Bit of an odd one bare with me and I'll try and explain it.

 

Bit of background first; Car is at stage 1 (decats, apexi filter, Blitz SBC, i'll get to ecu in a mo).

 

I ran the car with the original stock ECU and was getting code 34 and NO reading from the left hand o2 sensor. I put the det down to upgrades and standard ECU. But I was a bit confused about the dead o2 sensor.

 

Anyway, today I changed the ECU to a JWT chipped one and set the TPS to 0.46v. Ran Conzult again and was getting code 55, which was a relief. The timing also settled at 15 from 23 once the engine had got up to temp.

 

Now the odd bit; The lefthand o2 had come to life but the voltage reading on it was jumping about all over the place :wacko: Is this a sign that the sensor is dying and should be replaced, or do I have another problem?

Code34 does not mean Detonation. It means the ECU is not receiving a signal from the Detonation sensor. The problem is either the sensor itself or the wiring/connectors between it and the ECU.

 

Code34 is reset everytime you turn of the ignition, and is often an intermittent fault. If you have reset the ECU error codes with conzult then you will need to take the car for a drive and up to boost to trigger a code34 if its still occuring.

 

While the car has code34 issues then the ECU runs with Safety maps and reduced boost. Since your using an EBC then it cant control your boost but it can still use the Safety fuel and timing maps, significantly affecting performance. Although some aftermarket ECU's have been known lack safety maps.

 

O2 sensors, run as a open loop system at idle, which means at Idle they will not register, and the ECU uses standard oxygen data.

 

The o2 sensors must be tested at 2000rpm+ where the system operate in closed loop feedback mode, and their voltage should swing from low to high (lean to rich) about once a second.

Edited July 16, 201114 yr by Yowser

Code34 does not mean Detonation. It means the ECU is not receiving a signal from the Detonation sensor. The problem is either the sensor itself or the wiring/connectors between it and the ECU.

 

Code34 is reset everytime you turn of the ignition, and is often an intermittent fault. If you have reset the ECU error codes with conzult then you will need to take the car for a drive and up to boost to trigger a code34 if its still occuring.

 

While the car has code34 issues then the ECU runs with Safety maps and reduced boost. Since your using an EBC then it cant control your boost but it can still use the Safety fuel and timing maps, significantly affecting performance. Although some aftermarket ECU's have been known lack safety maps.

 

O2 sensors, run as a open loop system at idle, which means at Idle they will not register, and the ECU uses standard oxygen data.

 

The o2 sensors must be tested at 2000rpm+ where the system operate in closed loop feedback mode, and their voltage should swing from low to high (lean to rich) about once a second.

 

Thanks for that, makes sense. The bit I'm confused about is the ECU reading code34 and conzult not showing any voltage on the 02 sensor for two days, I tried unplugging cleaning the connector etc but still nothing. As soon as I replaced the ECU for a chipped one then the code 34 vanishes and hasn't come back and the o2 is showing voltage but it is not steady and is spiking about 3 times a sec (approx)?

Unfortunatley the car can't be taken for a drive yet as I've still got a lot of work to do on it.

 

Should I just bite the bullet and replace the o2 sensor based on the odd readings from conzult? The right o2 is holding a steady voltage and not moving.

IIRC the O2 sensor plug and the det sensor plug are around the same location - top/back of engine bay. May be worth checking they're plugged into the right connectors ;)

IIRC the O2 sensor plug and the det sensor plug are around the same location - top/back of engine bay. May be worth checking they're plugged into the right connectors ;)

 

Have done mate :)

"The o2 sensors must be tested at 2000rpm+ where the system operate in closed loop feedback mode, and their voltage should swing from low to high (lean to rich) about once a second."

 

Did you do that? You're supposed to see the voltages bounce back and forth when you hold it at 2000 revs, that shows a healthy O2. You say the right is staying at a voltage, is that at 2K revs?

"The o2 sensors must be tested at 2000rpm+ where the system operate in closed loop feedback mode, and their voltage should swing from low to high (lean to rich) about once a second."

 

Did you do that? You're supposed to see the voltages bounce back and forth when you hold it at 2000 revs, that shows a healthy O2. You say the right is staying at a voltage, is that at 2K revs?

 

Not yet, will do in the morning. Just finding it a bit odd that the voltage on one is stable but the other one is all over the place.

I've no idea about the voltages but the way to test them is at 2k revs as above ;) And I'm sure there's a reason for testing them at 2k revs think it's to do with getting them at operating temperature

Couldn't sleep again last night :blink: so I read the Conzult manual from page to page a few times. I now have a better understanding of the signals I should be getting etc..

 

I got Conzult on today and brought the revs up to 2100. Right hand o2 was pulsing nicely but left hand stood at a steady 0.32v and didn't move.

 

So, unless I'm reading it wrong, the left hand o2 is faulty and needs to be replaced. ECU diag code was 55 so the ECU can talk to the sensor.

I'd make sure the connector is nice and clean but it does look like it needs replacing.

 

If you want to check it's reading the O2 sensor, just unplug it/plug it back in with conzult running

I'd make sure the connector is nice and clean but it does look like it needs replacing.

 

If you want to check it's reading the O2 sensor, just unplug it/plug it back in with conzult running

 

The connections are nice and shiny mate :sailor: I'll get one of Mr F's nice new o2 sensors and get it replaced.

 

Thanks for your help bud.