adeste

So here is the story. My 97 maxima died on me while driving it (engine just shut off - no weird noises or shutters/shaking when it happened). I was able to get it restarted, but it died again about 3 seconds later. I had it towed back home and ran a few tests to figure out the problem.

Here is what I know so far:

-When I try to start it, the engine turns over, but there does not seem to be any combustion in the engine.
-Only 1 code for knock sensor, which has been there for years.
-Battery is good with 12.4V. Also, I hooked it up to a charger when cranking the engine so it would stay charged during testing.
-Fuel pressure (tested with gauge) is good and all spark plugs smelled like gas.
-2 coil packs were bad - no spark, but weirdly enough they passed the resistance test.
-All spark plugs are good (tested by plugging them in to known good coil packs and getting spark)
-I tested every cylinder coil pack connector and they all have battery voltage on the power wire and continuity on the ground wire. The signal wire on each connector had about 400mV when cranking (no clue if this is good or not).
-Cylinders 1,2,4,5 have no spark when a known good coil pack and spark plug are connected to them.

Other things to note:
-My car has had intermittent hard starting problems for several months now
-My tachometer does not work - it started having erratic needle movement and then had now gone 360 degrees around the dial and rests on the back side of the stopper peg.
-I replaced my crankshaft position sensor (pos) a few weeks ago, which seemed to help with the hard starting

I tested all of the cylinder coil pack connectors by taking a known good spark plug and coil pack and connecting them to each cylinder one by one and cranking the engine. I know that two of the coil packs are bad, but I don't know why cylinders 1, 2, 4, and 5 have no spark when there is a known good coil pack and spark plug connected to it and wires at the connectors seem to be good? If I am getting spark in 2/6 cylinders, then my crankshaft position sensors and cam shaft position sensors should be good right?

Any ideas on what could be wrong and how to fix it?

vqmaxman

The first thing here you should do is pull the codes than check from there. I think it must be a short in the harness or coils. I feel as if you might have the p1320 ignition signal code verify and check the whole process. I am leaning towards the signal from the ecu to the harness are not going through. I do know they had a tsb on this harness or short your talking about theirs a harness that mounts over the struts towers pass side. Those tend to break and flex alot so get that looked into also since this is a electrical issue.

JvG

This makes sense.

It would be well worth it to read that TSB.

One could replace the bad wires and solder in new ones.

I had a Volvo 145 once with a similar issue.

I disconnected the plug to the ecu . I ran a jumper wire from the ecu plug to its destination on the sensor. I connected the jumper wire to the wire at the sensor with an short jumper cable with alligator clips on both sides. Then I touched the leads from an ohm meter to the long jumper wire and also to the connection at the ecu connector.

There will be an individual color coded wire from the ecu connector to a given coil

Experiment on an coil which still works.

let's say that the wire from the ecu to one of the coils is black with white tracer. You would see such a wire color at the coil You would see the other end of the same wire at the ecu connector. I'll call it Bw.

1. run a wire from under the hood at the coil connector , through the car door, and all the way to the ecu connector. I'll call it RED wire.

2. Attach a short wire with alligater clips to the coil plug. You might need to shove a paper clip or something into the injector connection. Attach alligator clip to that. Attach the other alligator clip to the RED jumper wire.

3. Now go to the ecu connector in the car. Touch one probe of the ohm meter to the Bw wire at the connector. Touch the other probe to the RED jumper wire.

4 a good Bw wire from the ecu to the coil will read close to 0 ohms.
a faulty one would read higher ohms. A broken wire would read infinity ohms.

do the same procedure on all coil wires. Probably 12 tests need to done

now let's say the Bw wire shows 0 ohms.

1. Find the wire bundle at the strut.
2. Unwrap it.
3 test the Bw wire at each side of the strut. It will probably read Infinity ohms.
4. Cut the Bw wire at the forward end of the strut.
5 touch one probe of the ohm meter to the cut wire, and the other to the coil connection. It should read 0 ohms. This would confirm a broken wire at the at the strut.

I understand that Nissan sold a repair kit of color coded wire and connections which replaced the bad section.. I'd buy that if it's still available. Otherwise, solder in some other wire. Cover the splice with brush on insulation.

This procedure will take quite some time, but should save your car.





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adeste

I did the test for all ignition coil wires to the ecu. Tested ECU pins 1,2,3,7,8,9 to their respective signal wire on the coil pack plug and all wires had continuity with resistances ranging from 0.4-0.6 ohms. Based on this it seems as though this part of the wire harness is good? Any other ideas?

JvG

I'm certainly not a tech, but I'd say the wires appear to be in good condition

A further test would be to wiggle the wire bundle in the suspect area near the strut while the engine is running. The engine should sound the same way as you are doing the wiggling. Sould the engine start sounding better or worse, suspect the wire bundle.
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CMax03

iTrader: (3)

Possible defective crankshaft position sensor.... Check each coil pack connector for 12 volts during cranking...