changed my spark plugs the other day at my fathers house.
we didnt unplug the throttle bodies just pushed them aside.
advanced auto sold me the wrong plugs, i went to return them and when i got home my father had cleaned the throttle bodies with a tooth brush and carb cleaner.

so i didnt think anything of it until the car was turned on and my idle was at 2k and the check engine light came on.

so did the relearn and the light went off but the idle stayed high.
did the relearn where you hold the engine at 2k for a few min....
it calmed the idle down a bit but it isnt right.

now im not sure why but i have a few other problems as well.

if i am slowing down the engine is fine above 2k rpms, but once i go below that the rpms jump back up to 2k every few seconds and the car surges.
but if i stop the car the idle goes to 1k and stays.
also the car when i put it in drive, it will accelerate through 1st gear and then gain speed in second but not shift to third, all on its own.

and other problem is when going down the street, it goes fine at speed, but if i let off the gass it grabs hard and decelerates quickly. if i put it in manual mode in the same situation the tq converter lets go and i coast. when the cruise control is on the car does not do it either, only when in drive.

please help i know its a laundry list and prob no help but i love this car and need it to work correctly

any questions please ask. any advise please give

thanks

 

I replaced spark plugs last week and I am getting the SAME EXACT ISSUE. I did not clean the throttle bodies however. But, I did disconnect the MAF sensor and take off the TBs. When I turn my car on, it will initially idle at 2k, then drop down to 1k-1200rpm range. My driving symptoms are the same as yours as well... My friend at the Infiniti Dealership hooked up the computer to my car, and read the code as an Idle issue. So, we tried to adjust the RPMs of the idle and the lowest it would go to is 825 at complete Idle. keep in mind that I do have the UPREV tune, but I used to idle at less than 825rpm before the spark plug change anyways.

 

This could be your problem...this is from the following throttle body cleaning diy thread:

https://g35driver.com/forums/v36-diy...le-bodies.html

Do not disconnect the harness connector! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It's very important to NOT disconnect the harness.
If it is disconnected, and the butterfly is moved while cleaning;
the ECU will lose the closed or zero position of the sensor.
If that happens the car may not start or may run poorly.

If the cable is disconnected you have to perform a
"THROTTLE VALVE CLOSED POSITION LEARNING" procedure for the ECU.

 

^ could be but its not a problem even if you did, just do the pedal reset method and it will take care of the idle situation. Also the car starting up at 2k and then slowly dropping to 1200 and then finally to ~700rpm is totally normal on cold startup for our cars.

Maybe if you disconnected the battery the car is relearning your driving habbits, i suggest you check and make sure that all your harnesses, hoses and connections are back on the TB and MAF, then redo the TB reset and then drive the car for a day and you should be alright.

Also you do NOT want to use toothbrush or other abrasive things on the TB plates since these newer plates have some sort of teflon type coating on them that you dont want to scrub off so its better to use a lint free towel or MF.

 

so its been a little while. ive done a few diff resets to the computer and tb's
the car got better and better with time. i may have just freaked out the system a little bit.

the only problem i am still getting is my transmission still grabs hard betwwen 40 and 65mph it wont "let go" when i let off the gas.
any suggestions?