[Tmck]

My 340xi used to be way quicker than it is now. I currently have basic bolt-ons CAI, DP with BM3 tune and xHP as well. When I put my foot down from a stop, 1st and 2nd gear basically goes all the way to redline before upshifting and it just doesn't accelerate as fast anymore. Before my shiftpoints for 1st would be aro
I don't know if this is a contributing factor but recently my ambient temp sensor shorted and my car is now reading the outside temp as -40F, my AC basically doesn't work and it throws a CEL.
Could the lag be caused by the CEL?

[Skyhigh]

There are too many unknowns and too many variables in your post to be able to draw any conclusions.

- "Doesn't accelerate as fast anymore" - this is a subjective statement. Best to put some objectivity to it and make measurements. 0-100 time? 100-200 time? Have you logged it?
- You then start talking about changes in the upshifting, which directly points at xHP.... tried flashing back to stock? Looking at your xHP settings? Gearbox parameters?
- And then you drop a CEL in the equation as well.... what do you think - can the cause of a "Check Engine Light" have an impact on the Engine itself or is it just an amber light?

Start with fixing the obvious.

[johnung]

Originally Posted by Tmck

My 340xi used to be way quicker than it is now. I currently have basic bolt-ons CAI, DP with BM3 tune and xHP as well. When I put my foot down from a stop, 1st and 2nd gear basically goes all the way to redline before upshifting and it just doesn't accelerate as fast anymore. Before my shiftpoints for 1st would be aro
I don't know if this is a contributing factor but recently my ambient temp sensor shorted and my car is now reading the outside temp as -40F, my AC basically doesn't work and it throws a CEL.
Could the lag be caused by the CEL?

No way to narrow down your issue from the limited information that you provided. It could be caused by many things.

In the past when I have felt a reduction in power, once it turned out to be a bad tank of gas that logs showed was causing a lot of ignition timing corrections. Another time it turned out to be that I needed new spark plugs and coils.

[njdangelo]

Originally Posted by Tmck

My 340xi used to be way quicker than it is now. I currently have basic bolt-ons CAI, DP with BM3 tune and xHP as well. When I put my foot down from a stop, 1st and 2nd gear basically goes all the way to redline before upshifting and it just doesn't accelerate as fast anymore. Before my shiftpoints for 1st would be aro
I don't know if this is a contributing factor but recently my ambient temp sensor shorted and my car is now reading the outside temp as -40F, my AC basically doesn't work and it throws a CEL.
Could the lag be caused by the CEL?

At the very least we will need codes to be able to even begin diagnosing.
Have you tried the obvious first step of reflashing trans tune and bm3? When did the problems start? Why not fix the ambient air temp sensor as More than likely that is playing into your problems.

[Tmck]

Originally Posted by njdangelo

At the very least we will need codes to be able to even begin diagnosing.
Have you tried the obvious first step of reflashing trans tune and bm3? When did the problems start? Why not fix the ambient air temp sensor as More than likely that is playing into your problems.

I have an appointment made for Thursday to get it replaced. I've tried re-flashing both bm3 and xHP even clearing the code but nothing seems to work. If it is the sensor I'll make an update with it if the problem goes away.

[njdangelo]

Originally Posted by Tmck

I have an appointment made for Thursday to get it replaced. I've tried re-flashing both bm3 and xHP even clearing the code but nothing seems to work. If it is the sensor I'll make an update with it if the problem goes away.

I think it will remedy the issue. If your engine thinks it's -40 out it's going to try and run hot to get itself to safe operating temp. One way to do that would be high rpms

[Tmck]

Originally Posted by njdangelo

I think it will remedy the issue. If your engine thinks it's -40 out it's going to try and run hot to get itself to safe operating temp. One way to do that would be high rpms

Also the code was P0073

[G.Newt]

Originally Posted by Tmck

Also the code was P0073

Don't use generic P codes. BM3 will give you the BMW-specific codes. Take care of the CEL and take some logs of your car running. You're asking strangers on the internet to speculate without data. We're helpful strangers lol, but a log would be mint to help see what's going on with your car.

[Tmck]

Just an update. I made the appointment to get my Temp Sensor fixed at my local Midas since my dealership is over an hour away. Happy to say the issue went away and the car is back to what feels like full power.

The actual error codes that triggered the CEL are 10B105 and 10B106