Infiniti Q45 Rough Idle Diagnosis

Resolving Rough Idle
By Jesda Gulati

Fuel Injectors – Bad gas or regional mixtures tend to result in
early injector failures. A fuel smell in the cabin also hints
at injector problems. Non-OEM injectors are not recommended.
Learn how to test your injectors

Fuel System- Purchase a can of BG44k
from Infiniti of Scottsdale and add it to a 3/4 tank of gas.
Repeat this in 2 months. Chevron w/Techron can be used every
3000 miles if BG44k is not available. However, despite being
the best off-the-shelf choice, it is not nearly as effective
or cost-efficient. Gas-line water remover (such as Heet or
GasDry) ought to be added to every tank of fuel that contains
ethanol.

A fuel rail flush typically costs around $130 at a dealer.

Electrical – A bad
alternator, battery, battery cables or terminals will fail to
properly charge the battery and can cause idle
fluctuations. Optima is the preferred brand of battery for the
Q45. A temporary fix is to charge the battery using a separate
charger, or have a place like Autozone
do it for you.

MAF Sensor
– Steps on how to clean it for $3. A failed MAF (mass air
flow) sensor or MAF connector can cause
fluctuating idle, stalling, and bucking at any speed. The MAF
connector changed in 1995. A MAF or connector can be purchased
from Scottsdale Infiniti. A used MAF may work as well.

Throttle Body – Steps on how to partially clean it for $3.

Auxilary Air Control – How to clean the AAC for improved idle and
cruise.

Knock Sensors or KS
Bad Gas
Seafoam
Oxygen Sensors or O2 Sensors
Crank Angle Sensor or CAS
Throttle Position Sensor
or TPS