Rough Running On Initial Cold Start - Reprogram PCM

This PI was superseded to update model list specifics. Please discard PIP3956B.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers may complain of an intermittent rough running concern that lasts less than 1 minute after they cold start the engine. Once this occurs, it will not occur again until the vehicle cold soaks with the engine off for at least 4 hours or more. Typically, no DTCs will set when this occurs but it is possible that a P0300 and/or P1400 may set if the concern lasts long enough.

If the SI diagnostics do not isolate the cause of this concern, reprogram the PCM with the latest TIS2Web calibrations and re-evaluate the concern. The calibration titled "New calibration to address cold start idle surge and hesitation, when using fuel with low volatility properties", or any that follow, is designed to address this concern.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.