14point1 lambda sensor acting up.

[Yves]

I have the following : when driving I noticed the engine was running rough. I checked my lambasensors (have a sensor in each of the 8 exhaust tubes) and sure enough number 4 EGO would peg to the other end as if I had a dead cyl. The cyl however was firing as the exhaust tube was as hot as the others. I reasoned that the ego was making the cylinder way to rich, so I shut off my ego control (set up as per cyl pid control).

Now the sensor seems to act normal when starting up, meaning showing a reading of in the 13 range and after a couple of seconds in the 16 range. Then it goes to very lean (+19). When starting up the cyl seems dead, but sometimes it fluctuates back to normal readings for about half a second and then returning to dead lean.

Checked the wires but nothing abnormal there.

Not sure what this could be. Bad sensor, bad lambda module.

PS : the ego's are all connected through a iox.

thanks for the input.

[Yves]

Meanwhile I switched sensors and it's definately the sensor which is bust. Does this happen often with a Bosch LSU 4.9?

[Toma]

Meanwhile I switched sensors and it's definately the sensor which is bust. Does this happen often with a Bosch LSU 4.9?

Yes, these sensor are killing me.

A couple years ago, I switched over all my LSU 4.2 dyno widebands, to the "better" 4.9, and sensor life was killing me, as is that they skew rich with a little age. Day to day, I was using an AEM, a Techedge 3e1, and a Ecotrons.

I got so frustrated, i am now using my old standby "lab grade" NTK sensors from ECM. (afm1600, afm1000) and a ballenger afr500v2 with NTK As well.

I am looking into going back to 4.2's. I just emailed 14point7 actually, asking if he will still build 4.2 units.

[Yves]

d*** that's really bad news

[Toma]

d*** that's really bad news

Yeah, just talked to 14point7 and he will not support the 4.2 anymore.

A few guys I talk to that do a lot of E85 and methanol tuning are killing the 4.9 routinely, and I just spoke to syvecs, and then Life Racing, they do no support the LSU internally at all with their ecus, NTK only.

Id buy 4 more NTK controllers, but the sensors need to be mail ordered for me, and the day to day ones I use are $180 each.

I'll have to order the AEM 4 channel ASAP before they redesign it, as its still 4.2.

[nathaninwa]

Aem's failsafe still runs the 4.2. Think they'll redesign the 4 channel setup? Could be worth a call into aem tech this week

[Yves]

Any ideas what makes them so fragile ?

[DaveEFI]

Any ideas what makes them so fragile ?

Did you follow the guidelines as to sensor positioning/fitting? A wideband IIRC can be cooked if too close to an exhaust valve and not raised out of the direct exhaust flow.

My 4.2 is 6 years old and still fine. But is fitted after the two exhaust banks combine.

[Yves]

This one was right before the collector. I have a WB in each exhaust pipe. So it's roughly some 25' from the exhaust valve. It's approximately in the 10 o'clock position (no other way to mount it in this tube). There is another one just like this one and that one is holding up fine as well as the other 7.
Seeing the comments I'm wondering how long they will keep going.

[DaveEFI]

This one was right before the collector. I have a WB in each exhaust pipe. So it's roughly some 25' from the exhaust valve. It's approximately in the 10 o'clock position (no other way to mount it in this tube). There is another one just like this one and that one is holding up fine as well as the other 7.
Seeing the comments I'm wondering how long they will keep going.

This might help. It reckons on a minimum of 1 metre (40") from the exhaust valve - or space the sensor out of the direct flow.

http://wbo2.com/lsu/position.htm

[Yves]

It's on a longer bung and not directly in the exhaust stream