ninerwfo

Hi folks, have just replaced my third O2 sensor in 6 months, only getting about 3 track days out of them. I am running MS3 PnP Pro with a 14Point7 Spartan2 controller on ethanol, using the Bosch LSU 4.9 sensor. When I talked to the guy from Bosch, he said two things I need to change are:
(i) move the sensor bung to the 10 O'clock position (the downpipe fabricator installed it in the 12 O'clock position), and
(ii) install a circuit (or even a simple switch) that delays applying power to the controller until the engine is warm and running.

Each time I have lost a sensor, it seemed follow a longer-than-normal cold start. So, it is my suspicion that I am indeed wrecking the sensors because they are being "thermal shocked" by water droplets coming down the cold exhaust at startup.

Currently, power to the controller comes from the ignition barrel (switched 12v as per instructions), BUT, this is most definitely powering the controller and heating the sensor at the first "click" of the key, when the fuel pump is priming.

With a track day coming up I have just bought and installed a new sensor - but I won't have time to make a power delay circuit - would it be okay to simply put a switch on the +12V power wire to the controller, switch it off, start and warm up the engine, then turn it on to power the 02 sensor once everything is warm and dry?

Also, is anyone out there running some sort of circuit that automatically delays power to the O2 controller until a certain RPM and/or temperature is reached?
Thanks.

HarryB

Yes, a friend has done this in his S2000, and I plan to do the same on mine. The simple way is to use a timer triggered by the ignition, to power on the WBO via a relay after a given time. The more complex but preferred way would be to trigger one of the ECU outputs based on a set of conditions (CLT and total run time?), which triggers a relay to power the WBO.

90LowNSlo

I don't know about delaying the power to the O2 controller (seems like bad idea but what do I know)...

But uh, I'll just leave this here: https://www.ebay.com/itm/DC12V-Time-...224?nav=SEARCH

acedeuce802

iTrader: (1)

You can use a relay with the signal tapped into the fuel pump signal. It won't delay the heating beyond when the engine cranks, but it least the O2 sensor won't be warming up before cranking.

DNMakinson

iTrader: (3)

Never had an issue with 4.2 sensor on Innovate LC-2 controller. I have regularly run KOEO to make tuning changes, or to allow for pre-heating to get AFR readings during the starting sequence. Also, when hot, to download SD card Logs. Same sensor and controller for 5 years. Sensor located about 30 inches from turbo exit, right after downpipe mates with rest of exhaust.