Exhaust Noise On Cold Start Up - keywords 4.6 air LD8 L37 leak pump secondary

This PI was created to include 2007 model year. Please discard PIP3546.

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

Some customers may comment of a pulsing noise from the engine that occurs during the first minute when starting the engine after sitting for several hours. This noise may be mistaken for an exhaust leak or AIR pump noise. It is actually normal combustion noise caused by aggressive fuel and spark to heat the catalytic converters in order to meet more stringent 2006 model year emission requirements.

This is normal engine noise, and no repairs should be made in an attempt to improve it.

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.