My 2004 Nissan 350z stalls at idle and rides rough when in gear

I was driving on the highway today, and when I turned onto the exit ramp and put the car in neutral I noticed my gear shifter shaking back and forth pretty violently. I looked down at the tachometer and saw it idling at less than 200 rpm’s in neutral. I got to the light and my car stalled. I turned it back on and I had to feather the gas pedal just to keep the car running. I was able to make it to my local car mechanic with one foot on the gas pedal and my hand on the e-brake. It runs a little rough when in gear but at least it keeps the rpm’s up enough to stay running. The check engine light never came on. My guy said that he didn’t have the appropriate diagnostic machine, but he’s afraid I might need a new throttle body and a new computer which may cost 1000’s of dollars. I think the code he told me that he found was P0506. He sent me to a guy that deals only with Japanese cars, but they won’t be able to look at my car until Monday.

Any thoughts? Hopefully something that doesn’t cost 1000’s of dollars. And if I replace the throttle body does that mean I have to replace the computer too? Is there something that I did or that I didn’t do that I should have been doing that could have caused this to break?

This is going to be a long weekend,

It could be something simple (to fix, maybe not simple to find) like a vacuum leak. Beyond doing some basic testing for vacuum leaks, it probably makes sense to replace the PCV and the engine air filter. You might get lucky. If not, next step would be a test to see if the cat is plugged. All those things are relatively inexpensive. After that & becoming potentially more expensive, probably remove the throttle body for a bench inspection. Maybe all it needs is a basic throttle body cleaning job.

After that, throttle body replacement and/or PCM replacement would have to be considered.

Any idea of what a typical price for a throttle body replacement and a PCM replacement would be? Ball park? I live in Woodstock GA.

This car requires a scan tool capable of two-way communication with the car to set the idle. If the battery has gone dead or had very low voltage then the idle learn procedure must be completed using a proper scan tool.

Don’t jump into any parts replacement until the throttle has been cleaned and the idle learn procedure performed.

Replace the battery first if it is weak.

Also check the vacuum lines. The last time I saw this a line had fallen off.

No issues with my 2007Z yet but my 2003 Murano which has similar engine (3.5L) had similar problem (would not idle properly) and it had throttle body problem according to dealer.

Turns out it was a bad air flow meter. It was a quick fix and my 350z is purring like a mountain lion.

Thanks for your posts and big thanks to Long Brake and Tire and The Toy Shop in Marietta GA.