Tuning and O2 sensors

[adrian k]

Right so the tuning saga goes on with my XR8, had it down at Ford today to their ECU guru to see why the SCT flash tuner wont talk to the car. Turns out there is something funny with the ECU, its in some mode that wont allow them to write to it, but this is the 3rd ECU that has done it, so it must be something else in the car. Any ideas?? they have logged a tech support request with Ford Aus, but given its an AU, they doubt any support is still available.

I got them to check why it is running rich while they had it. Couldn't find anything out of the ordinary, but he commented that with the Herrod headers, the O2 sensors where only reading the rear two cylinders on each bank (one branch of the Y), and so weren't seeing the whole picture. Firstly how big an issue could this be, and poeple out there with after market headers, where are your O2 sensors located?

[b2tf]

Originally Posted by adrian k

I got them to check why it is running rich while they had it. Couldn't find anything out of the ordinary, but he commented that with the Herrod headers, the O2 sensors where only reading the rear two cylinders on each bank (one branch of the Y), and so weren't seeing the whole picture. Firstly how big an issue could this be, and poeple out there with after market headers, where are your O2 sensors located?

I dont know how they would be able to narrow down what cylinders it is and is not reading - my understanding is that the 02's actually read the oxygen levels in the exhaust therefore what's coming out of the cylinders as such probably couldn't be differentiated being that far 'up' the exhaust system.

My difillippo 4 into 1's retain the 02 sensor in the factory position, i did have to extend the wiring loom for the passenger side one about an inch but that was done by cutting the tape that holds the loom behind the engine in the bay back a bit and just allowing the wiring for the sensor to go down that little bit further.

[adrian k]

Originally Posted by b2tf

I dont know how they would be able to narrow down what cylinders it is and is not reading - my understanding is that the 02's actually read the oxygen levels in the exhaust therefore what's coming out of the cylinders as such probably couldn't be differentiated being that far 'up' the exhaust system.

My difillippo 4 into 1's retain the 02 sensor in the factory position, i did have to extend the wiring loom for the passenger side one about an inch but that was done by cutting the tape that holds the loom behind the engine in the bay back a bit and just allowing the wiring for the sensor to go down that little bit further.

na, what he was saying is that because the O2 sensor is only in the flow of the rear 2 cylinders in each bank rather than a mix of all 4, that the feedback to the ECU could not be accurate. makes some sense give that the rear cyclinders tend to run hotter than the front ones.
either way its too rich, i get a big waft of fuel/exhaust smell when i pull up to a set of lights.

[b2tf]

Originally Posted by adrian k

na, what he was saying is that because the O2 sensor is only in the flow of the rear 2 cylinders in each bank rather than a mix of all 4, that the feedback to the ECU could not be accurate. makes some sense give that the rear cyclinders tend to run hotter than the front ones.
either way its too rich, i get a big waft of fuel/exhaust smell when i pull up to a set of lights.

Yeah i gather that but if your sensors are still in or close to the factory position how can that be the case?

How old are the sensors?

[adrian k]

Originally Posted by b2tf

Yeah i gather that but if your sensors are still in or close to the factory position how can that be the case?

How old are the sensors?

Assume they are original.

The factory position for the sensor is after all 4 header pipes meet, but with the HMS headers, it only were 2 headers meet, so its only half the picture.

[Stav]

If your cylinders in your engine are in good condition..spark and fuel is all perfect then it wont make a big difference.

[STINKY NINJA]

Get new sensors if they are original because they would almost be stuffed if your car has done over 80000-100000km

[CRAIGAU3220]

Originally Posted by adrian k

Assume they are original.

The factory position for the sensor is after all 4 header pipes meet, but with the HMS headers, it only were 2 headers meet, so its only half the picture.

Get your self some new ones, mine were only 64000km and they were lazy on cold start.....symptoms were lumpy,fuelled up rich idle on cold start and hunting idle more often than not.

[adrian k]

yeah, probably money well worth spent.

[b2tf]

Yeah this is where I was going with asking how old the sensors are. Mine have done 85,000 and the thing is running richer every day. Time for newies.