Intermittent no start and stuttering under acceleration

Hi,

The problem starting sounds like it is related to the transmission range sensor. If the vehicle doesn't recognize what gear it is in, it won't start.

With the codes you have, the U codes are specific to the CAN bus system. There is a break down of communication between the modules which can be associated to the non communication with the range sensor/transmission control module.

I don't know what kind of scan tool you have but I'm going to provide the diagnostics for both of the U codes you have. The U1000 is the one I can break into the transmission related issue. I will provide that first. The attached pics correlate with the directions.

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2003 Nissan-Datsun 350Z V6-3.5L (VQ35)
Transmission Control System
Vehicle ALL Diagnostic Trouble Codes ( DTC ) Testing and Inspection U Code Charts U1000 Transmission Control System
TRANSMISSION CONTROL SYSTEM
DTC U1000 CAN COMMUNICATION LINE

Description
Controller Area Network (CAN) is a serial communication line for real time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent malfunction detection ability. Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation (not independent). In CAN communication, control units are connected with 2 communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only.

On Board Diagnosis Logic
- This is an OBD-II self-diagnostic item.
- Diagnostic trouble code "CAN COMM CIRCUIT" with CONSULT-II or U1000 without CONSULT-II is detected when TCM cannot communicate to other control units.

Possible Cause
Harness or connectors (CAN communication line is open or shorted.)

DTC Confirmation Procedure

NOTE: If "DTC Confirmation Procedure". As been previously conducted, always turn ignition switch "OFF" and wait at least 10 seconds before conducting the next test.

After the repair, perform the following procedure to confirm the malfunction is eliminated.

WITH CONSULT-II

pic 1

1. Turn ignition switch "ON". (Do not start engine.)
2. Select "DATA MONITOR" mode for "ENGINE" with CONSULT-II.
3. Start engine and wait for at least 6 seconds.
4. If DTC is detected, go to "Diagnostic Procedure" below.

WITH GST
Follow the procedure "WITH CONSULT-II".

Diagnostic Procedure
1. CHECK CAN COMMUNICATION CIRCUIT

With CONSULT-II
1. Turn ignition switch "ON" and start engine.
2. Select "DATA MONITOR" mode for "A/T" with CONSULT-II.

Pic 2

3. The "CAN COMM CIRCUIT" is detected.

Yes or No?
Yes >> Print out CONSULT-II screen, GO TO 2.
No >> INSPECTION END

2. CHECK CAN COMMUNICATION SIGNALS

With CONSULT-II
1. Turn ignition switch "ON" and start engine.
2. Select "CAN COMM SIGNALS" in "DATA MONITOR" mode for "A/T" with CONSULT-II.

>> Print out CONSULT-II screen, go to "Precautions When Using CONSULT-II".

Pic 3

CAN Communication Signals

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2003 Nissan-Datsun 350Z V6-3.5L (VQ35)
CAN Communication
Vehicle ALL Diagnostic Trouble Codes ( DTC ) Testing and Inspection U Code Charts U1001 CAN Communication
CAN COMMUNICATION
DTC U1001 CAN Communication Line

Description
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent error detection ability. Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation (not independent). In CAN communication, control units are connected with 2 communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only.

On Board Diagnosis Logic

pic 4

On Board Diagnosis Logic

DTC Confirmation Procedure
1. Turn ignition switch ON and wait at least 3 seconds.
2. Select "DATA MONITOR "mode with CONSULT-II.
3. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

EC-CAN-01

pic 5

Wiring Diagram

Diagnostic Procedure Step 1

pic 6

Diagnostic Procedure

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As far as the drivability, it could be related. You mentioned there are aftermarket converters on the vehicle, so I don't know if other things have been modified. If you can, let me know what the short term fuel trims are so I can see of the sensors are working and how the PCM is reacting.

Take care,
Joe

No problem. I have to be honest, with the right equipment it shouldn't be too hard to find. However, without it, it can become a nightmare. If you can follow the procedures, it should lead you to the issue. Please note that the U1000 can be specific to the trans and the engine. Since you mentioned the issue with the park indicator, I feel that is the direction you need to go. Certainly, that will cause the starter not to engage.

Let me know if I can help. I'll try my best from here. LOL

Take care,
Joe

Where are you hearing the clicking while the shift indicator is flashing? Take a look at the attached pic. The item I circled is the park position switch and the park interlock switch. Could the sound be coming from that area?

By the way, the fuel trims look good.

Joe

Hi,

Do me a favor. Check to see if it is the shift lock relay. You should be able to feel it by placing your fingers on the relay. I attached a pic below.

If that is the relay, switch it with a different one having the same part number. Or here is a link that explains how to test one:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know.
Joe

Hi,

It is possible that by removing and reinstalling the relay it is not making a good connection. See if that changes. As far as the fuel trims, they look good. For some reason I have no column to hear what is happening and I can't quite see the RPM's on the scan tool.

Joe

Did the RPM's skip on the scan tool or anything when you felt the misfire? Without codes, it is going to be tough. I have a feeling the relay had a bad connection with the start issue. Lets hope that is resolved.

For the misfire, you have checked the basics such as fuel pressure, for vacuum leaks, and also have you checked wiring to the crankshaft position sensor? Also, you did scan the entire can bus system, correct?

One other question, what RPM does that seem to happen?

The reason I asked about the RPM's is because if the crank sensor stops sending a signal, you will lose spark. Also, the RPM signal would be lost. Check the wiring to it. The sensor itself may be going bad. Take a look through this link:

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

Interestingly, a faulty sensor may not set a code. I attached a pic below of the sensor location. It is a bit vague. LOL Let me know if it helps.

Joe

It's below the bank 1 throttle control actuator. Here is another pic that may be more helpful.

Per Alldata:
"The crankshaft position sensor (POS) is located on the oil pan facing the gear teeth (cogs) of the signal plate."

Joe

Hi,

That is correct. You would see the tachometer jump because it would lose signal.

With no codes and nothing seeming out of the ordinary (other than the problem), we may have to wait until it gets worse. You are certain that all grounds to the body and engine are good, correct?

Joe