rpms almost don't go up when shifting from drive to park

[areznik]

Hey guys, I noticed something strange. Lately, my rpms are not so stable neither in park nor in drive. More interesting is that when I shift from drive to park, the needle sort of raises but then slowly reaches the same rpm level as in drive. It also produces noticable vibration. The rpms in idle and park are about 550. Usually I had about 600-650 in drive, and +50 in park. About two months ago I flushed the engine by doing the BG service. Also, the idle was adjusted by the dealership. Two weeks ago, I cleaned the idle valve and this problem appeared afterwards.

Any advice or suggestion will be greatly appreciated, Andre.

[Q45tech]

Is the air bypass screw on the IAC 2.5-3.5 turns out from the bottom. What is condition of PCV valve and all PCV hoses [clean inside]?

[areznik]

The air bypass is 2.5 turns out. I struggled with it because for some reason it was easy to screw it in but very hard to unscrew, but eventually I made 2.5 turns.

I assume that the air system should be clean because I have done the BG service at the local nissan dealership. They remove the air filter and then spray the BG carbon cleaner into the TB while the engine is working. Shouldn't this take care of the pcv valve and air lines too?

[Q45tech]

No, the BG TB spray doesn't take care of anything but the front of TB, the plenum and runners. You still have to manually clean everything else.

You may need a few more turns out on IAC, till you get everything clean...........obviously it's not getting enough air.

[areznik]

Q45Tech, you were right! I made another turn out and the idle is fine now. The only problem with the idle that I noticed is when the engine is warm and I turn the egnition off and then on, the idle in park seems to bounce +/- 10 rpms and is a little bit lower than the usual. If I drive the car, then stop and put the gear in park, the idle is perfect. What's up with this? I read Wes's article about idle, and you pointed to the temp coolant sensor (whose conn #2 is responsible for supplying coolant temp to ECU). So, I pulled the connector out and then in. The wires were all clean.

Is there anything else? Oh, you mentioned PCV valve. I replaced this one about 12k ago (about 18 months ago). How can I check if this valve is good when I remove it?

Thanks, Andre.