2008 Infiniti G 37 Idle Issues

[Joe A]

Thanks for considering to help!
I recently purchased a 2008 Infiniti with 50,000 miles and no warranty. I'm having issues with idle. From a cold start, vehicle idles at 1200 rpm and will adjust to 600 rpm after warm condition. Driving immediately upon idle at 600 rpm, vehicle shifts and drives and stops perfectly. However - after a period of time and distance, INTERMITTANTLY the idle will hover at the 900 to 1000 rpm range. This presents a problem while applying the brake to stop, and causes the transmission to "surge" while stopping. While experiencing this higher idle situation, acceleration within transmission from a stop is "jerky" until it shifts into 2nd or 3rd gear within the automatic transmission. After parking and allowing vehicle to set for a period of time, everything reverts to normal and perfect operation conditions.
It was suggested I clean the Idle Control Valve - I cannot even find this valve. Also suggested was an Idle Sensor may be suspect, along with a Transmission Speed Sensor. Is this a typical problem for these vehicles? Also someone stated that the Torque Converter may be locking up. I am at a loss to correct other than inspecting the Mass Air Flow Sensors which looked new, and inspecting the Intake Air Filters which were clean. Is it off to the Dealer time? Thanks for taking the time to read this post. Joe A

[joe603]

There is a procedure to reset the TB sensor in the FSM (link in my sig). I'd try that first. What does the car do if you put it in neutral when you feel this surging? If it goes past 1,500rpm then you should take it to a dealership (if the adjustment procedures don't fix the issue).

This is NOT a common problem with these cars. Good luck!

[Joe A]

Joe 603,
Thanks for the technical advice. Out of desperation, I at this moment am at an authorized dealer having my G37 serviced. Seems there was a service bulletin addressing this issue from Infiniti, and I just authorized to have the ECM "relearned" along with cleaning the (2) throttle body intakes. Quite, expensive - I just hope it cures the problem... Thanks again for your reply. Best regards. Joe

[audtatious]

Which TSB are they applying?

I don't remember a TSB requiring the TB's to be cleaned as they are quite sensitive. Below is a listing of TSB's for the G37.

http://www.infinitig37.com/Infiniti-G37 ... itins.html

[Joe A]

Audtatious, Thanks for the listing of TSB for my Infiniti. The specific bulletin that predicated the service today was: ITB07 - 048b - 2008 G37 Intermittent / Short Duration Small RPM Increase During Braking.
This TSB only applied to certain G37 produced before the stated date, and of course, mine fell in that category. $509.00 later, including replacing engine air filters, relearning idle, reprogram of ECM per TSB, and finally de-carbon of two throttle bodies, the issue is resolved. I was told I will need a new battery as CCA is below specs, but I refused that service today. I did think it thru and asked the question.. Should continuous 12 volt battery / or battery charger energy be applied while changing out the old battery and was told YES in order to maintain the ECM upgrade from today.. These vehicles are truly Computers on Wheels!!! Joe A

[audtatious]

Sometimes it is easier to let Infiniti deal with issues but dealer charges are always far more than I like to pay. The services in the TSB for the most part can be done as a DIY but sometimes time is an enemy. I hate to know what it's going to cost to fix my tilt steering as there is either a sensor issue or one of the two motors is hosed. I'm too old to be working under the dash to troubleshoot more than the switch itself.

[telcoman]

Audtatious, Thanks for the listing of TSB for my Infiniti. The specific bulletin that predicated the service today was: ITB07 - 048b - 2008 G37 Intermittent / Short Duration Small RPM Increase During Braking.
This TSB only applied to certain G37 produced before the stated date, and of course, mine fell in that category. $509.00 later, including replacing engine air filters, relearning idle, reprogram of ECM per TSB, and finally de-carbon of two throttle bodies, the issue is resolved. I was told I will need a new battery as CCA is below specs, but I refused that service today. I did think it thru and asked the question.. Should continuous 12 volt battery / or battery charger energy be applied while changing out the old battery and was told YES in order to maintain the ECM upgrade from today.. These vehicles are truly Computers on Wheels!!! Joe A

On my previous 06 G35 when it was time for a new battery the dealer price was within $20.00 of others. I let the dealer install a 700cca battery and everything worked after they replaced the battery.
They also washed and vacuumed my vehicle.

Telcoman

[joe603]

Glad you got the issue resolved...I just wish they could have only done the free relearn, before charging you for simple cleaning (that unless you're in the desert or like to drive on dusty trails, you probably didn't need). Next time, don't let the dealer clean anything or replace filters...probably $50-100 for a $20 aftermarket filters and who knows how much for spraying the throttle bodies with carb cleaner.

For the battery; just get a decent one from autozone and DIY.