QuestionQUESTION: Greetings
I’ll include the whole story so you’ll have all the info.
94 Maxima
3 liter VG30E SOHC
167000 miles
A few months ago, the engine began to run rough. Spark plugs were due, so I replaced them. The old ones looked great, nothing abnormal. Still ran rough. Replaced spark plug wires since they were also due. Still ran rough.
Connected timing light to each spark plug wire – all 6 wires triggered the light. Took spark plug wires off 1 at a time. Removing wires 1,2,3,5, & 6 made things worse, but removing #4 made no difference. Problem cylinder found. Logically assumed injector was clogged/bad. Ran a few bottles of Techron in fuel (not all at 1 time!). Wife said it did OK for a short time, then back to missing.
A week ago, wife said she barely made it home. Checked spark plug wires again with timing light – all triggered light. Listened to injectors with homemade stethoscope. No click at #s 3, 4, and 6. Bought Haynes manual.
PCM codes were 51 for injector circuit fault and 33 for O2 sensor.
Replaced all 6 injectors with Beck/Arnley remanufactured injectors (O-rings were included, and of course new air plenum gaskets and fuel filter). Could not afford new injectors. All PCM codes gone, except 55 – no faults detected. Ran great! I drove 5 miles or so up and down hills, gearing up and down, kicking it in and loving it! Wife said it had not run that good since we bought it (close to a year ago). I’m a happy shade tree mechanic!
Wednesday, she warmed it up in the drive, and when she went back out, it had stalled and wouldn’t start. I came home that night, and discovered it was out of fuel – AHHHH! Got gas, started up after a few seconds of cranking, but still ran rough. Listened to injectors – all 6 were ticking. Put timing light on all 6 spark plug wires – no spark on #1, intermittent on #3. All others triggered. It was raining all day.
Replaced distributor cap and button next day – this was also due, plus I had the cap off for the 4 days it took to replace the injectors (didn’t work on it for 4 days non-stop – had other stuff to do as well). Still ran rough.
Today, I did the timing light check again – did not trigger on 1, 3, 4, & 6. Others seemed somewhat sporadic. Some mentioned above occasionally triggered when either revving or decelerating.
I removed the distributor cap and button, opened the cover on the camshaft position sensor, and no oil or dirt – optical wheel looked very clean. Put distributor back together. (Learned that from this site, probably 5 or 6 hours of browsing!)
Checked distributor cap and button resistance – OK per Haynes.
Checked coil wire – OK per Haynes.
Bumped engine until pulley’s 0 degree mark almost at pointer, distributor button was 180 degrees away from #1 cap terminal, so I’m assuming it was on the exhaust stroke and timing belt has not slipped.
Coil primary and secondary resistance OK per Haynes.
Called local auto parts store – was told if I didn’t have a spark tester I could use an old plug instead. Coil wire and all 6 plug wires produce a yellow spark – I wouldn’t call it blue or white spark. Not sure if coil or transistor is bad? I think I should get a blue or white spark.
Engine starts quickly. No more than a second or 2 of cranking needed.
So what am I missing? After the initial joy of it running so good a few days ago, my mechanic’s heart is now very heavy! I’m over $500 into it now, and am trying to follow good troubleshooting methods to avoid unnecessarily replacing parts.
There are other tests yet to be performed in the Haynes manual, but I hope this is one of those “Duh” moments and am just overlooking something.
Thanks for any info!
ANSWER: Darryl,
I am thinking distributor here. You could remove it and disassemble and clean with tuner cleaner and dry out and reassemble and see if that works. It has been my luck with older Nissan cars that the distributor is the most common problem since it triggers both the injectors and the plugs. Also, if you have checked the fuel pressure and it is good then no problem there. But, if it is low or non existant after you start the car the air meter will probably be defective. You see, after the car initially starts the fuel pump gets power from the air meter if it senses air is flowing. If the air meter is defective or the air intake hose, the one from the air meter to the throttle body is loose or cracked, or if you have a large vacuum leak the car will die. All that work you did could have taken a vacuum line out since the age of the vehicle. I would check over all the vacuum lines to be sure... Email me back if you need more.
---------- FOLLOW-UP ----------
QUESTION: Thanks for the quick reply!
One thing to clarify - the engines starts rather quickly considering all this, and it does not stall at all while idling. I've let it run for 10 minutes or so while doing the timing light test. I have not tried to take it for a drive since I don't think it's strong enough.
I did replace several vacuum lines that cracked or were brittle.
The Haynes manual gives a test method for the Camshaft Position Sensor - remove distributor, reconnect the wiring, turn key to On, turn rotor slowly and watch the volt meter at various wires. Do you agree with that?
AnswerDarryl,
I would check the mass airflow sensor and the throttle position sensor using the Haynes Manual and a digital volt ohm meter. Also use the following to check the engine computer codes.
The ECU has a window on one side to view a red LED and a green LED - when checking fault codes, a red flash is worth 10, and a green flash is worth 1. So for example, the code to say that everything is functioning normally would be 5 red flashes and 5 green flashes - the code is 55.
The ECU has 5 modes of operation, for diagnostics codes, it has to be set to mode 3.
1. Make sure the screw next to the viewing window is turned clockwise.
2. Turn the ignition on
3. Both LEDs with flash once, then a pause, then a second time, then a pause, etc. etc. up to 5 times then will repeat the process. After is has flashed 3 times then turn the screw completely anti-clockwise. - this will select mode 3.
4. The LEDs will now flash codes. 55 means that everything is normal. The rest are written below.
5. When finished, turn the screw back to clockwise and the ECU will reset itself automatically.
Don't worry about the '5th cylinder misfire' and '6th cylinder misfire' or anything, the codes are the same for all Nissans.
11 Crank Angle Sensor/Camshaft Position Sensor.
12 Air Flow Meter/Mass Air Flow Sensor.
13 Engine Coolant Temperature Sensor.
14 Vehicle Speed Sensor.
21 Ignition Signal.
22 Fuel Pump.
23 Idle Switch.
24 Throttle Valve Switch.
25 Idle Speed Control Valve.
28 Cooling Fan Circuit.
31 ECM.
32 EGR Function.
33 Heated Oxygen Sensor.
34 Knock Sensor.
35 Exhaust Gas Temperature Sensor.
36 EGR Control-Back Pressure Transducer.
37 Knock Sensor.
38 Right hand bank Closed Loop (B2).
41 Intake Air Temperature Sensor.
42 Fuel Temperature Sensor.
43 Throttle Position Sensor.
45 Injector Leak.
47 Crankshaft Position Sensor.
51 Injector Circuit.
53 Oxygen Sensor.
54 A/T Control.
55 No Malfunction.
63 No. 6 Cylinder Misfire.
64 No. 5 Cylinder Misfire.
65 No. 4 Cylinder Misfire.
66 No. 3 Cylinder Misfire.
67 No. 2 Cylinder Misfire.
68 No. 1 Cylinder Misfire.
71 Random Misfire.
72 TWC Function right hand bank.
73 TWC Function right hand bank.
76 Fuel Injection System Function right hand bank.
77 Rear Heated Oxygen Sensor Circuit.
82 Crankshaft Position Sensor.
84 A/T Diagnosis Communication Line.
85 VTC Solenoid Valve Circuit.
86 Fuel Injection System Function right hand bank.
87 Canister Control Solenoid Valve Circuit.
91 Front Heated Oxygen Sensor Heater Circuit right hand bank.
94 TCC Solenoid Valve.
95 Crankshaft Position Sensor.
98 Engine Coolant Temperature Sensor.
101 Front Heated Oxygen Sensor Heater Circuit right hand bank.
103 Park/Neutral Position Switch Circuit.
105 EGR and EGR Canister Control Solenoid Valve Circuit.
108 Canister Purge Control Valve Circuit
