Im wondering if anyone know how the ecu fires the coil packs? Is it from negative pulse or postive pules.

 

The FSM manual shows a 4-volt positive-going pulse to fire the plug... I've been digging into this subject lately.

 

The coil is always hot (if the key is on) and the ECU grounds the proper wire to complete the circuit. The ECU doesn't send a + signal to the coil.

Fred

 

hmm, learn something new every day. I always thought it sent a + signal to fire them.

 

This practice is very common with Nissan. (GND)

 

That is how the injector circuit works. That is NOT how the ignition circuit works.

If you look at the wiring diagrams in the FSM, you will see that there is an NPN power transistor in each ignition coil. The ecu is connected to the base, the emitter is connected to ground and the collector is connected to the primary side of a transformer which is also built into the coil.

To fire the plug, the ecu sends a pulse signal (~+5V relative to GND) to the base. This "closes the switch" allowing current to flow in the transformer primary (12V - collector to emitter - GND) The high voltage induced in the transformer secondary causes a spark to jump to ground via the spark plug.

 

...^.....^.....^

What I said......

 

can some one test and see what kind of voltage is present at the coil connecter(unpluged from coil) Check the 1 red wire and ground it to the 2nd wire and see what kind of volts you at the connector

 

The red wire is at battery voltage when the key is on / car is started.
Connecting the red wire to anything else isn't recommended -- fuses blow or coils slag down !

 

OK I WAS saying connect a muti meter to the red wire and then ground it to see how much voltage it has stock. Im having problem with the eu install of melting coils and my voltage is at 23.0 volts.

 

Does anyone know what it should test stock at the coil?

 

^^^^^^^ What he said ^^^^^^^^


Are you back-probing the coils to check the voltage?

 

im putting the red probe on the red wire at coil connecter(1st wire)and putting the ground probe on the engine from the multi meter

 

Er.. Is the meter set on DC volts? Is your ground wire (black probe, I guess) on the engine block - hard ? If you do that, leave the black lead on the block, lift the red lead and touch the + battery terminal. With the car off, should read about 12.5 - 13.5 volts, depending on charge.

The red coil wires - they are all connected together - should read the same as battery voltage, whether key is ON or engine is running.

 

yes its on dc. But mine are reading higher maybe due to emanage ultimite!

 

Unplug all six coils and the three emanage connectors.

Measure the DC voltage between any coil connector red wire and the engine grounding point with the ignition ON.

 

I stand corrected, I guess I was wrong. I thought they worked more like a relay. I still don't understand all of your terms in relation to the FSM's coil diagram but I'm trying. Can you tell us which part of the coil diagram (EC 118 for the 95 Maxima electronic FSM) correlates to which of your terms?

thanks,
Fred

 

You will find a thousand pages or more that will explain transistor terminology better than I can.

http://www.talkingelectronics.com/Fr...ts/Page10.html

You can use the figures in the above link and reference them to the wiring diagrams in the FSM.