General High fuel consumption and lambda sensor

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General High fuel consumption and lambda sensor

James, how did you put the new O2 sensor on? Did you use some copper grease or other kind of grease? Because you are not supposed to use grease or to tighten the sensor very much. The sensor needs some fresh air to enter trough the thred, to work correctly. That's what I found about them after I've replaced mine and I did use cooper grease, and unfortunatly the after cat sensor is completley stuck now, even with the grease. I find the info with the space for air a bit strange. I seems to me that if the space is not seald, air would't go inside the exhaust, it would be the other way around, exhaust fumes would be pushed out there.
When you put the tester on the car again, check the value for "Engine load" and how many steps is the idle motor opened. That could be the problem, the idle air control valve (IACV). If it is bad it causes bad fuel/air ratio and the ECU keeps trying to make the ratio right again and there you go, you are in a vicious circle. Bad IACV can even give bad O2 readings, without the O2 sensors being bad. See how it goes with a new MAP sensor and have the IACV in sight, if the problem persists.
 
James, how did you put the new O2 sensor on? Did you use some copper grease or other kind of grease? Because you are not supposed to use grease or to tighten the sensor very much. The sensor needs some fresh air to enter trough the thred, to work correctly. That's what I found about them after I've replaced mine and I did use cooper grease, and unfortunatly the after cat sensor is completley stuck now, even with the grease. I find the info with the space for air a bit strange. I seems to me that if the space is not seald, air would't go inside the exhaust, it would be the other way around, exhaust fumes would be pushed out there.
When you put the tester on the car again, check the value for "Engine load" and how many steps is the idle motor opened. That could be the problem, the idle air control valve (IACV). If it is bad it causes bad fuel/air ratio and the ECU keeps trying to make the ratio right again and there you go, you are in a vicious circle. Bad IACV can even give bad O2 readings, without the O2 sensors being bad. See how it goes with a new MAP sensor and have the IACV in sight, if the problem persists.
I'm afraid that there is no possible way that allowing fresh air in through the tread is correct. It has a copper crush washer pre installed for a reason.
It is supposed to be an air tight seal.
I've fixed it now. I was actually the cat itself that was faulty.
Live data helped. It would only happen at just over 3000 revs. The gasses were getting between the cat and the pipe it is pressed into.
I spoke to the head diagnostic guy at fiat dealership.
He said it is a hard one to spot of you don't know but they have a weakness there
New cat fitted and been great for a few months now.
Thanks for everyone's help
 
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