I recently upgraded my computer to an i7-975 CPU and Windows XP Pro 64bit Operating System.Too start with, I did not notice the following problem, but it is possible that I just overlooked it and it has been there since my upgrade.First of all, I have lost my mixture control in both FSX and FS9 for leaning the fuel mixture. There is no response in either fuel flow or EGT temperature until I reach the cutoff point, at which point it does shut off the fuel. For years I have successfully used the CH Control Manager for mapping my CH Yoke in FSX. In FS9 this mapping is paired with the CMFS routine for the device.cfg file going long back before FSX was even released.I virtually never fly MSFS default aircraft with the exception of troubleshooting, which is applicable here. I have tried several third party birds both pay and freeware as well as the MSFS default Baron.1. In FSX when I startup with say the Default Baron (or Twin Bonanza), my Prop control seems to work fine. However, when I try to lean my mixture with the mixture lever, both the mixture lever and prop (RPM) levers move together (CH Yoke). Of course in this case, the mixture does lean but as a result of reduced RPM. I get the same exact reduction by only reducing the RPM with the Prop Pitch lever.2. If I download my CH map for FSX, the levers then work separately as they should, but leaning with the mixture has no affect with the exception that I can shut down the engines at the cutoff point.3. In FSX I went into my FSUIPC Joystick Calibration provisions thinking that this might be the problem and a new calibration might solve the problem. The response I get in FSUIPC when I try to calibrtate the Mixture lever is from the Prop Pitch (direct) in FSUIPC. When I try to calibrate Mixture (direct) in the FSUIPC Joystick Calibration section, I get no reaction at all from any CH lever.4. So I went to FS9 to see what I had.5. Yoke levers work properly.6. Calibration for mixture and/or prop pitch respond properly and with the proper identification.7. However, again trying to lean with the mixture lever has no affect until I reach the cutoff point at which point the fuel is cut off and the engines shut down.8. Tried the same thing with the keyboard commands. I get the same reactions with the exception that the mixture and prop levers do not move together when the mixture lever is moved in FSX. Of course they do not move together either in the mapped mode with the yoke.Note: I have checked and rechecked axis assignments and sensitivities in the FS provisions. They are normal and correct for what has been the case in past operation for years. I have never made axis selections and/or modifications within FSUIPC.Has anyone else been down this road, or have any idieas?Respectfully:RTH

Did you check your 'Settings/Realizm' to be sure that 'Enable auto mixture' isnt checked?

I've had problems like that in Vista64 using Saitek 64 bit drivers. In the game controllers applet all axis appear to be working correctly, but prop and mixture axis is not working correctly in FSX. After I uninstalled the Saitek driver and used the default MS driver the problem went away. I only use the Vista64 system for testing, so I didn't work on the problem any more than that.scott s..

Thanks loads Jay:I never knowingly fly that way, nor even thought of it.Both "Enable Automixture" and "Unlimited Fuel" were checked which is a no no in my book.Thanks so much. Everything snapped into place when I removed those checkmarks.I wish I could blaim this as a senior moment, but it was a dumb thing to forget.Greatly appreciate your reply:RTH

Thanks loads Jay:I never knowingly fly that way, nor even thought of it.Both "Enable Automixture" and "Unlimited Fuel" were checked which is a no no in my book.Thanks so much. Everything snapped into place when I removed those checkmarks.I wish I could blaim this as a senior moment, but it was a dumb thing to forget.Greatly appreciate your reply:RTH

Glad to help