Hi All!
I own Saab 9-5 (MY03, 2.3t, AT) and there is problem with AFR - till 4000 rpm the mixture is too lean (14,7) on WOT. It seems like the car do not want to pass from Closed Loop to Open Loop and runs under the oxygen sensor control. From 4000 rpm till cut off on WOT the mixture is very good (AFR 11-12).

It seems that it is very hard or even impossible to get in Open Loop mode on WOT. I was observing the Xacc (throttle opening level) and it reached 100%. I have been also observing mreq against mair parameters and they were equal and reached 1178. I am talking about Open SID indications.

The car was checked on different BINs, so it is not a software, but hardware problem! Then we've checked hardware: ECU, fuel pump, FPR, MAF have been replaced. Fuel lines have also been checked. Fuel filter is brand new. Oxygen sensor seems to be right. All indicators observed in open SID seem to be correct. Probably, there are no vacuum leaks.
Please, help me to solve this. Do you have any idea what is wrong!?

Regards,
Kuba