2005 Infiniti G35 Coupe Fuel Trim Too High

Hello I own a 2005 Infiniti G35. The long term fuel trim for bank 1 shows 6% at idle and 13% at 2500 rpm while the bank 2 long term fuel trim show 2% and 11% respectively. The oxygen sensors show (bank 1 upstream) .3 volts at 65 mph and .6 volts on bank 2 upstream at 65mph. I'm getting a catalyst running inefficient on my scanner and I need to find the root causes.

This is a symptom of an underlying problem. There is no vacuum leak because when accelerating long term fuel trim increases. Any suggestions on what I should be looking for that could be the root causes of this catalytic converter problem.

Answer:

Look into possibly a defective or contaminated MAF (mass air flow) sensor and/or low fuel pressure faults. More than likely your Infiniti G35 is running lean causing the ECU to increase fuel trim. This condition may cause a false catalytic converter efficiency code and is considered a "fake" breathing problem.

If fuel trim is high at idle AND at 65 mph diagnose further for a vacuum leak behind the throttle plate.

We also recommend ensuring your Infiniti's oxygen sensors are working properly by administering a propane enrichment test. Check that O2 voltage switches below .02 to above .09 when propane is added. Note the rear oxygen sensors should produce a relatively flat .45 volts during steady load.

posted by SmogTips Support