CSI rough down low

[Nigt3]

Hello, I have a 850csi (which I love) the car stays in Germany mostly and i’m In the uk so it doesn’t getting driven very often, apart from holidays. I’m in Germany now and have just took the car for a run and down low in the Rev range 1000-1600rpm when accelerating there is a slight miss/roughness that wasn’t there before. Any ideas where to start with the problem??
Thanks in advance

[shogun]

are the 2 batteries fully charged?

[Nigt3]

Shotgun, thanks for reply. Wokke done some work on the car and he reduced it down to one battery, the battery was completely flat and I had to jump start the car today, could this be anything to do with the problem?

[8eights]

Both sides of the engine running at idle?

[Nigt3]

Yes

[shogun]

low voltage can cause problems. Low voltage will set for example EML on the M70 in limpmode if it drops below 11V for more than 90sec. Low voltage will also cause problems with the IKHA (heater/ac), memory for seats/steering and transmission will go into limp mode.
Maybe you drive it a bit so that the DMEs go back to normal.

[kiwiCSi]

A similar issue on my CSi some years back, was traced to one bad plug wire.

[Nigt3]

Thanks for reply’s guys, will be looking into this soon!