Well, the time has come that I actually have to make a profile and ask questions. So far I've gotten through the past two years of owning a Z simply by using the search button, but that's no longer working. My name is Cliff, I drive a white, 2007 350z 6spd base model. Nice to meet everyone. Now, on to the issues I can't seemingly fix on my own lol.

Since this is my first post, I'd like to start by saying that this is not my first car, nor is it the first car I've ever modded. I've owned a few cars ranging from Evo's, to several 240sx's, SC300's, and even an SRT-4 (I know, you don't need to tell me), but this IS my first Z. I'm pretty mechanically inclined, so I like to think, although this problem has me stumped. Over the holidays I decided to install a ported Z1 lower manifold. Pretty simple, straight forward install that took me about two hours to do taking my time. In the process, I decided to clean my throttle bodies. Now before you flame me like the idiot I already feel I am at this point, I was ignorant to the fact of how sensitive these cars are. I used 'throttle body cleaner' to 'clean the throttle bodies' and in the process moved the butterfly plates manually to thoroughly clean the carbon off. I thought my car would appreciate this basic maintenance procedure; it did not. To add, I did not disconnect my battery.

After starting my car, the idle was surging all over the place, usually holding around 1500 RPM's, and the throttle was severely "lagging" on deceleration in between gears. After hours of searching through this forum and others, I tried everything. I manually did the throttle body learn probably 100 times. I reset my ECU multiple times, and even re-flashed my tune (UpRev) to try and fix it. Nothing worked. At this point I concluded that my throttle bodies were toast.

The next day (Thursday) I sourced a set of used, but good, VHR throttle bodies from a friend of a friend. After installing them (I disconnected the battery this time) I tried all of the relearning procedures again. Reset my ECU and re-flashed my tune again (I thought it might help), still not cured. I sprayed the entire motor with carb cleaner looking for vacuum leaks, but nothing changed. My AFR's are perfect during WOT, albeit slightly richer than usual due to colder weather, indicating that there are no vacuum leaks. Friday morning I decided to take the car to Nissan to have them force learn the throttle bodies with Consult. Immediately it fixed the issue and I was the happiest person around; however, the moment I turned my car off and restarted it, it was back to the usual high idle, RPM decal lag, and throwing the P0507 code.

Now, at this point the car has leveled off somewhat. After the car warms up immediately after a cold start, my idle is relatively normal around 850rpm and the RPM decel lag isn't as noticeable, but, the more I drive during one start, the worse it gets. After 20 minutes of driving it's back idling around 1100-1200rpm and the decel lag sucks.

After talking with my tuner, Z1, and another Z shop, we've come to a consensus that my ECU has a bug in it. I also found a specific UK site that suggested the same thing, confirming the theory, but honestly, I'm not 100% sold on it. So here I am, asking you, the forum members, if you have any other ideas. I know throttle body issues are common on these cars due to the immense number of hours I've spent reading about it at this point, but the solutions other people have had have done nothing for me. I need some fresh thoughts. I apologize for the essay, but I wanted to be as descriptive as possible. Thanks.