Water Injection and Lambda Sensor

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Hi Everyone,

I've got a turbocharged Volvo which has been running WI for nearly a year now. The car was running fine until recently, it was found to be running very lean (AFR 13.5 at full load open loop; I gather it should be in the low 11s). All fuel components eg. MAF, fuel pressure reg, fuel pump etc. were changed but no change at all to AFR. Injector duty cycle is around 100%. When running closed loop, AFR is 14.7.

Yesterday, it was found that both lambda sensors were giving inaccurate readings. At WOT, the sensor before the CAT was registering a very rich mixture ( 2V over what it should read) and the sensor after the CAT was registering a very lean mixture. Both were well out of normal accepted values and it has been suggested that both sensors may have been contaminated.

I am running a system 1s with 0.6mm jet and would like to know whether its possible that some of the atomised water (from windscreen reservoir, hence mixed with screenwash) may have gone straight out the exhaust valve and onto the lambda sensor, thereby causing inaccurate readings when the pump suddenly kicks in and lowers the intake charge temp.

Has anyone come across a situation like this before? I am really stumped because nearly everything to do with the fuel supply has been changed but not made any difference. The car is detonating severely (even with the WI system working) and I'm having to be very careful when driving it. Any suggestions or advice will be greatly appreciated.