My 2000 Maxima idles rough for exactly 30 seconds then idles smooth for 30 seconds. I've timed it and its exact. It sometimes dies during the rough idle period. Any ideas as to the problem? Engine light has not come on and no codes.

 

Interesting. If it was my car, I would check the battery voltage and see if it also goes up/down in sync with the car irregular idle. Of course, the next question is "What is the cause and what is the effect?", but checking the voltage is a place to start.

 

Do the RPM's jump up and down when this happens? Could be the IACV.

 

I already replaced the IACV and TPS. I'll check the voltage and see if the irregularity is in sync. Thank you for the suggestion.
If the car is not warmed up the engine dies when put into gear.

 

I was thinking MAF, but i dont know why it would happen every 30 seconds.

 

Use a code reader and check live data. Look specifically at the O2 sensors and see if their readings consistently change with the idle.
I'm going to assume you've got a vacuum leak.

 

I do hear a slight whistle in the engine. I thought that it being exactly 30 seconds that it switches from smooth to rough idle, might help pinpoint the problem.

 

My daughter's car is doing the exact same thing did you ever figure out what it was?

 

Crazy thing is iVe got the same issue right now and still can’t solve it, been ongoing for like 2 months now

 

we must get to the bottom of this! lol

 

Is the air conditioner compressor turning on and off?

 

That was the 1st thing I thought of when reading all of this. I think low coolant can trigger the compressor to go on and off.

 

My 2000 was doing the same thing but only when is was below 40°F. I replaced the IACV with a cheap 1 from Amazon. Actually made it worse. Bought the Hitachi IACV & it fixed it.

 

AC is off
However, I'm getting a code for random multiple cylinder misfires. Prior to this I had an ECM failure. The ECM was sent out and repaired and I also replaced all 6 ignition coils and spark plugs. Obviously to get to the back three cylinders the intake had to come off so even though I'm pretty sure everything got hooked back up I'm hoping a vacuum line got left off somewhere. Wishful thinking of course though lol