Rich until AC is on

[danielpalfrey]

Ok, I have a strange one, I have spoken to my mechanic and he is baffled. The car runs rich, but as soon as I turn the ac on the mixture leans out nicely, I also noted the more air was getting into the system with the AC on, TMAP live data shows this go from 30 to 40 when AC is on. The TMAP is new.

 

Does anyone have any ideas?

 

Dan

[BOF]

I have an idea but whether it is true is another matter: If you have an injector leak problem, it could be that the engine runs rich until it gets a little load, and thus a little more air.

Probably worth doing a leak off test.

 

[danielpalfrey]

Leak off test performed and there is nothing out of the ordinary.

I have been doing further tests, while driving the car barley touches 80 degrees (digital read out) if I idle the car up to 90 - 100 the car leans out.

My theory is that when the AC is on the car knows it is going to get cooler and has a "lower" running temperature so this leans the mix out.#

With the AC off the car is still running rich to Warm up as it has never hit running temperature. Maybe the thermostat is stuck open?

Does this sound likely or am I just plucking at straws?

Cheers

Dan