Technical Bravo t-jet o2 lambda problem

[Maxcrysis]

Hello,Ihave weird problem with my bravo searching for simillar problem but i cant find it.Long story my bravo was tuned 4-5 years ago and run flawess until now.The ecu don't want to switch to closed loop.The car hasn't check engine light or error codes for lambda sensor.
I buy two new sensors,doesnt work.The sensor was tested on diffrent car working perfect.
New ECU,same thing.
I Checked the pins of the lambda plug:
pin 1 power 14v
pin 2 PWM ground working(tested with bulb)
pin 3 Ground
pin 4 signal
The signal voltage stay at 450mv constant

 

[bugsymike]

Hello,Ihave weird problem with my bravo searching for simillar problem but i cant find it.Long story my bravo was tuned 4-5 years ago and run flawess until now.The ecu don't want to switch to closed loop.The car hasn't check engine light or error codes for lambda sensor.
I buy two new sensors,doesnt work.The sensor was tested on diffrent car working perfect.
New ECU,same thing.
I Checked the pins of the lambda plug:
pin 1 power 14v
pin 2 PWM ground working(tested with bulb)
pin 3 Ground
pin 4 signal
The signal voltage stay at 450mv constant

Is it possibly the original tuned setup used a competition Lambda sensor with a wider range and you have fitted a standard sensor?
Can you compare with the original one?

 

[Maxcrysis]

The car was tuned with the stock lambda sensor,nothing special.Last year pop up some error codes for lambda but I deleted the code and the sensor start working again and then stopped,no error codes change sensors and nothing.I suspicious pin 3 on lambda connector,it is always show ground doesn't matter if the car working or not.Is this normal?

 

[bugsymike]

The car was tuned with the stock lambda sensor,nothing special.Last year pop up some error codes for lambda but I deleted the code and the sensor start working again and then stopped,no error codes change sensors and nothing.I suspicious pin 3 on lambda connector,it is always show ground doesn't matter if the car working or not.Is this normal?

I don't know specifics for your car , usually two wires are the heater wires (1 and 2?)and the other two (3 and 4?)are for the lambda readings.
The low signal 450mv unchanging seems strange.
Are you able to check those wires at the ECU as well as at the O2 sensor as I have had rotten wires just a short distance from the ECU on a Fiat Grande Punto, it looked good on the outside.

 

[eeeno]

Have you been checking the voltage with OBD from live sensor data? Also check that the obd monitors have passed for lambda and catalyst for example. ELM- bluetooth fault code reader thing is a must-have if you want to find out if something's not quite right. Most of the time ECU will tell you and set a fault code but the thing is you need to be able to interpret it properly. Sensors usually last the lifetime of the car and very rarely some sensor may fail.

For example lambda may fail if the engine runs with poor spark plugs for a long time; wrong fuel mixture, coolant or oil deposits... It also kills the catalyst.

Also checking engine coolant temperature sensor may be a good idea because with old cars it used to be the key sensor which set the car to run in closed-loop. It may take a longer trip for the monitor to complete and if it fails it'll set a fault code. Other engine trouble is possible too, ECU's compensating for something. 1st lambda shows a range of voltage, take a note of the high and low values. 2nd one should remain fairly constant. Google knows the normal range for these.

 

[Maxcrysis]

The second O2 is turned off when the car was tuned because the exhaust system is catless.I checked the voltage from obd 2 and watching for fuel compensation (short fuel trim and long fuel trim) stay 0 because it is stay in open loop.I know how voltage looks like from lambda 1.Something is off and i think it is wire related.I checked wires to the ecu connector and they are all good,still not sure for 3 lambda pin connector what need to be.