I recently changed the knock sensor on my G35 coupe. Then when i went to turn it on after i put everything back my G was in limp mode. I couldnt rev past 1,500 rpms. I got it scanned and codes P2135, P0222, and P0123 came up. I then switched the throttle body and now my car starts but then the rpms drop and the car turns off. Help!

 

Does your car still throw a code/codes? If so go from there.......

 

I havent scanned it after that. But ive read online that its MAF problems. I think i might just end up taking it to a shop.

 

Have you gone through the ECU re-learning steps so the new throttle body can get calibrated?

 

I tried but its confusing. Do you think that can really be the reason my car not turning on?

 

You mentioned two different problems here.

Is the car not "turning on" as in, dash lights don't illuminate, fuel pump is not priming, engine is not cranking?

Or does it not stay running as you alluded to in your first post ?

 

Well yes it does turn on but doesnt stay on. So i meant to say do you think if i do that my G it will actually stay on and not turn off when the rpms drop.

 

OK. Thanks for that. I found this thread over at the 350z forums and it sounds very similar to yours. Try the following and let us know if anything changes.


Accelerator Pedal Release Position Learning

Operation Procedure
1. Make sure that the accelerator pedal is fully released.
2. Turn ignition switch “ON” and wait at least 2 seconds.
3. Turn ignition switch “OFF” wait at least 10 seconds.
4. Turn ignition switch “ON” and wait at least 2 seconds.
5. Turn ignition switch “OFF” wait at least 10 seconds.


Throttle Valve Closed Position Learning

Operation Procedures
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch is “ON”.
3. Turn ignition switch is “OFF” wait at least 10 seconds.
Make sure that the throttle valve moves during above 10 seconds by confirming the operating sound.


Now do the ECU Reset:

Operations Procedures

1. Confirm that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.
2. Repeat the following steps (2a and 2b) procedures quickly five times within 5 seconds.
2a. Fully depress the accelerator pedal (HARD).
2b. Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the CEL starts blinking.
4. Fully release the accelerator pedal (while the CEL is still blinking)
5. Wait about 10 second.
6. Fully depress the accelerator pedal and keep it for more than 10 seconds.
7. Fully release the accelerator pedal (The CEL light will continue to blink).
8. Turn ignition switch to “OFF” position and now you can start the car. The CEL light should be gone.


P0123
http://www.nissanhelp.com/diy/obd_codes/p0123.html

P0223
http://www.nissanhelp.com/diy/obd_codes/p0223.html

P1122
http://www.nissanhelp.com/diy/obd_codes/P1122.html

P2135
http://www.nissanhelp.com/diy/obd_co...35_nissan.html

 

It's hard to say how the ECU will react to a Fly-By-Wire throttle body it hasn't been calibrated to. Recently, I picked up a '04 350z (basically same as the G35 under the hood) and the car would start and idle, but as soon as you touched the throttle it would die. I had no CEL codes. I replaced the MAF and throttle body per recommendation of a knowledgeable source, went through all the steps for the ECU to calibrate the throttle body, and the car now starts, runs, and the throttle response is normal.

You might want to purchase a can of MAF cleaner, clean your MAF, then go back through the ECU calibration steps for the new throttle body. Those steps are critical to get the timing correct.....so it takes a few tries to get it right.

After the calibration, clear your CEL codes and see if the car will start and run correctly.

Here is the process borrowed from another forum:

From Technosquare website:

Please read all instructions and be familiar with them before any attempts.
A stop watch or an analog clock with a second’s needle will be useful.

ECU Resetting Procedures

Timing is extremely critical. If it is NOT DONE within the specify time, the ECU will not reset and the Check Engine Light (CEL) will continue to remain ON. A stop watch or an analog clock with a second’s needle will be useful.

Operations Procedures

1. Confirm that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.
2. Repeat the following steps (2a and 2b) procedures quickly five times within 5 seconds.
2a. Fully depress the accelerator pedal (HARD).
2b. Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the CEL starts blinking.
4. Fully release the accelerator pedal (while the CEL is still blinking)
5. Wait about 10 second.
6. Fully depress the accelerator pedal and keep it for more than 10 seconds.
7. Fully release the accelerator pedal (The CEL light will continue to blink).
8. Turn ignition switch to “OFF” position and now you can start the car. The CEL light should be gone.
If the CEL light continues to remain ON, repeat the above steps. Timing is EXTREMELY critical to resetting the ECU.

Edit: Added the "Easy Method" for ECU Reset

The Easy Method:

After experimenting with different timing, and reading posts by other members, I've come up with a condensed method of doing this reset. This method works EVERY time, even w/o a stopwatch. I've used this method successfully a dozen times, or so, now w/o a watch. After a few times, you won't need a watch or instructions. You'll get so darn good at it, you'll find yourself doing it while waiting at a traffic light.

Timing is not as critical with this method...no stop watch needed. Just count in your head...one-one thousand, two-one thousand, etc, or use stop watch. The most critical step is step #3....wait 10 sec, instead of 7.

1. Ignition "ON", count to 3.
2. Depress/Release pedal 5 times...hard and fast.
3. Count to 10 (not 7!) and fully depress pedal
4. Count to 12 (SES should be blinking), release pedal
5. Count to 10, depress pedal
6. Count to 10, release pedal.
7. Turn off ignition, then start engine. Done!

Accelerator Pedal Release Position Learning

Operation Procedure

1. Make sure that the accelerator pedal is fully released.
2. Turn ignition switch “ON” and wait at least 2 seconds.
3. Turn ignition switch “OFF” wait at least 10 seconds.
4. Turn ignition switch “ON” and wait at least 2 seconds.
5. Turn ignition switch “OFF” wait at least 10 seconds.

Throttle Valve Closed Position Learning

Operation Procedures

1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch is “ON”.
3. Turn ignition switch is “OFF” wait at least 10 seconds.
Make sure that the throttle valve moves during above 10 seconds by confirming the operating sound.

Idle Air Volume Learning (Throttle Position Learning)

It is better to count the time accurately with a clock.

Operation Procedures

1. Perform “Accelerator Pedal Released Position Learning”.
2. Perform “Throttle Valve Closed Position Learning”.
3. Start engine and warm it up to normal operating temperature.
4. Turn ignition switch “OFF” and wait at least 10 seconds.
5. Conform that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.
6. Repeat the following (steps 7a, 7b) procedures quickly five times within 5 seconds.
7a. Fully depress the accelerator pedal (HARD)
7b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the Check Engine Light (CEL) stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the CEL is ON.
10. Start engine and let it idle.
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure the idle speed and ignition timing are within the specifications.

 

Alright thank you and ill keep you up to date if anything happens.

 

I found out what was wrong. The throttle body harness was ripped and i connected it and relearned the throttle body and my G is running again!

 

Nice work!

 

Thanks for the help though 👍🏻