i have a problem with my engien. sometimes when i start up the car the car starts then turn of again by itself and this happnes sometimes. could it be from the SKUNK2 plenum i just installed or is this something else like low battery.

 

bump

 

Prior to shutting off, does your car idle roughly? If so, you may have a vacuum leak due to the spacer install. That was a spacer, right?

 

ya its a 5/8 skunk2 plenum spacer, i do have a play on the RPM during idel but only at startup. and as far as the plenum i have instaled it twise and i torqed the bolts i even have a gasket on the upper plenum.

 

Hmmm . . . I was going to mention the butterfly valve assembly in the throttle body, but you said that your idle is smooth prior to the engine shutting down.

 

what can be wrong with the butterfly valve i hear it open and close after shut down like normal.

 

bump

 

If you are idling smoothly, disregard the butterfly valve comment.

 

i cant think of anything that could be wrong. i took of the spacer and re-did the install and torqued all the bolts again and i still have that problem i cant think of anything. if the battery was bad then the car wouldent start at all right but im getting start then shutdown at the same time.

 

Maybe you could try the ECU reset procedure. Not sure though but it's worth a shot IMO. This stuff below is old so they may have a new method. I got this info back when I had an 03 coupe.

As taken Off the TechnoSquare Site for the 350z, should work for us too.
350Z ECU Resetting Procedures
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
with M/T depress clutch and hold it in.
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.

Accelerator Pedal Release Position Learning
Operation Procedure
with M/T, depress clutch and hold in.
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
with M/T, fully depress clutch and hold in
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.
with M/T, fully depress clutch, and hold in
5. Confirm 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.

 

i did a ECU. i just unhooked the Negative over night and got a reset.

 

any other thoughts?

 

Maybe while its running try to move the vacum hoses around and see if perhaps one might have a small cut that only leaks from time to time. Also if you need to hear for leaks you can take a piece of plastic hose and hold it to your ear(lol sounds funny) while you move the other end around the engine area to listen for leaks. Other then that, I would remove the spacer to see if the problem still exsists. Can't think of any other trouble shooting ideas at the moment.

 

if only cars could talk

 

They speak in a language called ODBII