Surging during low speed driving - just after cold coolant light off

[pjensen641]

I've searched the forum and TSB's. Anyone have a throttle surging issue while driving low speed (40mph) when the engine is just warming up? I notice a very subtle up and down surge of power and rpms. Its noticeable on the tach, maybe about 100 rpm max cyclic surging. The frequency is about one cycle per second. Almost as if the ECU was giving the throttle body a sinusoidal wave form. I have noticed it twice now. Temps have been in the 0-20 degree F range here lately. I notice a very subtle acceleration and deceleration of the vehicle when this occurs too. Never noticed it when the car is fully warm.

If you haven't already figured it out, I am an engineer

 

[Nodnerb]

I have actually noticed this a few times too. It is very subtle. I actually haven't taken note of the tach but I can definitely feel the surging.

 

[rimsy]

I had this occur yesterday morning - pretty cold morning (for the UK at least) and found it rather startling as the roads were damn icey! As you say only seems to occur at lowish speeds. I have my CX5 in for its first service soon so will mention it to my dealer.

 

[pjensen641]

I've only noticed it once more since i posted, and only for a very short time. Honestly, I'm not as sure that is was surging this time as I was last time. I had my OBDII scanner running but not logging and couldn't see any fluctuating numbers as far as MAP or timing. Hard to tell without data logging though. Maybe just a small instability in the ECU algorithms at extreme temperatures.