I bought a used 350z (2003 version) in Feb'13. At the beginning, there was a problem with the engine vibration and the mechanic had rectified it by replacing the ECU.

Soon after that, there is a bigger problem arised - the engine dies off automatically few seconds after starting. Then got to try a few times with cranking sounds but some times engines will ignite and some times not. This problem occurs every morning or after idle for few hours.

My mechanic has already done the engine relearn via computer, checked the mass air flow sensor, converter, crank & cam shaft sensors but still cant solve it. There is no check-engine-light and the error code is P1121 APS circuit.

Do you have any glue to solve it? The car is in the workshop for a month already and frustrated for not able to enjoy such a nice car since i bought it.

 

damn man hope u guys are able to fix it. Btw how many miles on the 03

 

First,is the "mechanic" working on your car familiar with the 350Z?
My first thought was to check the cam position sensor.You are
saying that there is no CEL but a error code?The code you are
providing is related to the throttle actuator.Has your mechanic checked
everything in this "drive br wire " circuit?I'd start there.

 

My mechanic self claimed a Z specialist but now i doubt his capability after this experience.. It is strange that there is no CEL but the engine problem still persist.. Sometimes if lucky the engine can start and have to hold at 2k rpm for about 5 minutes, then the engine will run smoothly. But once the engine stop for few hours or every morning, the problem will emerge again.

Do you guys know what wrong with my Z?

Some other expert told me that i need to do the engine idle relearn manually after changing the throttle body, is that right?

Odometer shows 55km.

 

you need to reset new throttle bodies after installation

 

As mentioned by JCity, and ZleeperZ the problem seems to arise from your throttle position sensor and the fact that they need resetting or recallibrating. This should solve your problem. I'd be inclined to take your Zed to a true Zed specialist who knows what they're doing as your mechanic appears to be hoping that if the CEL doesn't show then all is well when it obviously isnt.

 

check your vin with nissan and see if you got your cam or crank position sensor done. does it misfire at all?

 

I'd still start with the cam sensor.This is a common problem.How did your "mechanic" test the sensors(there are two)?Its strange that you are not getting a CEL.By your description of how your car is running,it sounds like the
cam sensors.Some guys just replace both.Don't know what the cost on
cam sensors is in your country or,the availability.I'd recommend getting
OEM sensors vs aftermarket.Nissan sensors here run about $100+ ea.USD.

 

if throttle body was replaced then thats the issue there. the problems you are saying can be 100% directly related to the TB

 

Thanks for all the advices.

My mechanic had already tested the cam and crank shaft sensors from another working condition Z car, but the problem still persist.

ZleeperZ, do you know how to reset the car after TB installation?

 

Went to the workshop today. The mechanic has replaced the throttle body and reset the TB with scan devise (Carman Scan Lite). But the engine still persist where it will stop few seconds after starting especially in the morning or the engine is cool. Sometimes, if got luck, the engine does not die off if the mechanic hold the acceleration at 2k rpm for 5min. Once the engine gets hot, then the problem disappear and engine can start & run smoothly. But the problem emerge again once the engine gets cold.

Any possible solutions?