I am running a ms3x with a Bosch 4.9 wideband sensor and in the last two years I have gone through three wideband sensors. I am using real Bosch sensors and when they die it will just go full lean after startup. Any ideas why this is happening or if anyone else has had this problem?

 

Mayba wanna specifiy your setup and where/how it was installed(orientation and distance to engine)

 

You've left out the most important thing - which controller/gauge you are using.

 

It is an AEM typical gauge.

 

I don't have that measurement on me. It is a decent distance from the engine. The downpipe from the turbo does nearly 90 degrees down and then the sensor is roughly 2' back.

 

Are you using spark cut (rev limiter/launch control/flatshift)? As this will quickly kill sensors.

 

I meant naturally aspirated or turbo with much higher exhaust temperatures. Distance can be an issue with turbo.

Same for the orientation, at the wrong angle it can cause condensation which will kill any sensor over time.
https://wbo2.com/lsu/position.htm

 

That post reminds me of an interaction I had on here around a year ago. Was having the same issues as OP except maybe even more frequently. It was sometime during winter/spring when it was cold and wet most mornings here. Made a thread and a fellow user instructed to wait 15-20 seconds after a cold start to turn the sensor on. Solved my issues.

"The sensor is manufactured from high temperature ceramic substances (modified Zirconium Oxides, etc.) and, although quite robust when used correctly, it is susceptible to thermal shock. This can occur if droplets of a liquid are sprayed onto the hot surface, as can occur during engine startup when water (that is produced during combustion) condenses on cool exhaust components."

 

I believe that's 90% of why AFR sensors die prematurely on aftermarket applications. Would be quite easy to program a logic output to trigger power (through a relay) to your AFR; "wait x seconds after engine is running and if CLT<x" or sth.

 

If you have it in the exhause manifold then you might want to put lower down, like just below the downpipe. Pointing downward to help ensure it is not sitting in any fluids.

 

In the manifold? People put them in the manifold??? lol