Q45 (1st Gen): Rough Idle Diagnosis

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Resolving Rough IdleBy 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.</font></p> 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 CASThrottle Position Sensor or TPS