poor_red_neck

1987 Nissan Stanza...

This is the engine that uses 2 plugs per cylinder with two coils.

Driving down the road one day it just cut off. Called a buddy with a tow-truck. After about 20 minutes it would start again. Ran long enough to drive it onto the flatbed then cut off. Got home and it ran just long enough to get it off. Since then it has not run.

I know its spark.

Fuel pump works, new fuel filter injectors test out fine. Its the ignition that's the problem.

I've tested and replaced the following:

ECU
BOTH Coils
BOTH Ignition control modules/Power Transistors (that's what nissan calls them)
Crank angle sensor
Distributor cap and rotor
Both EGI relays.
EGI 15A fuse.

Basically everything related to the spark.

I don't get it.

I took my old distributor off, and did the old trick I knew:

Put the ignition to the run position, and spun the distributor with a drill (off the vehicle).

Normally, this would "trick" the car into thinking that it was running, so you could see the injectors firing with a LED tester I made.

With this car, it doesn't do that. The fuel pump does come back on, I never bothered to check the injectors because the problem is not fuel related.

If I turn the crank angle sensor really slowly, the coil will fire at the markings for TDC of each cylinder (there are numerous dashes cut out, and 4 dashes cut out at 90 degrees). It will only fire the coil if I rotate it slowly, then stop once I get past one of those TDC marks. If I turn it by hand or by drill, the coil will not fire until I stop spinning.

So... I don't get it.

The crank angle sensor is sending a signal to the ECU. The ECU is sending a signal to the control module, and the control module is sending a signal to the coil. Now its just not doing it "fast enough" or every time. I've tried 4 different control modules and 4 different coils. All of them test out to specs (resistance and voltage) according to factory specs.

I'm at a loss. I've replaced EVERYTHING related to the ignition... at least that I'm aware of. Only thing that I can think of is the wiring harness. The harness is in physically great shape. Not de-hydrated from over heating, no "ghetto splices."


I've tested the coils. The resistance test checks out on both the low voltage terminals as well as the primary to secondary.


Any thoughts?

bikeman

Timing belt?

poor_red_neck

Nope.

Camshaft moves.

This has to be purely related to SOMETHING in the ignition circuits.

PapaCap

Interesting to take off the distributor and spin it. Never thought of that.

But have you taken a plug out, grounded the tip to chassis, and cranked the motor? Have your buddy hold a screwdriver in the plug boot (if you don't like him). You need to see if it's getting fire to the plug. I believe they sell a test spark-plug type light at any auto store. That way nobody gets juiced.

If the plug is not sparking, I would run a hot lead off the battery onto the ignition coil. See if that gets you some spark (you may have to run a ground, too...I haven't worked on that type of motor in a long time).

If that's not it, there may be an electronic module inside that distributor. I know 80-90 Ford 4 bangers would have the electronics in the distributor go out frequently with high miles.

Let us know what cha find out.

pc

poor_red_neck

Thanks papa cap....



Yes, with a plug grounded and connected to a lead there is no spark.

The only circuitry inside the distributor is the crank angle sensor (really its obviously a camshaft sensor, but the ECU uses this for its crank angle sensor instead of most cars being on the flywheel).

There are two coils. They both fire simultaneously. The control modules are about 2.5" X 2" on the back of the coils. As stated above, the coils and control modules test out per the factory service manual to be within spec. I have 4 total coils and 4 total control modules and have tested different configurations of them all with the same result.