which coil when?

[mshore]

Can some one help me by explaining where exactly where each of the coils on the 24Z plug into the Distributor cap? I may have switched them when replacing wires. One coil is nearer the radiator (on my 84 720) and the other coil is nearer the left fender.

Back story:

The truck drives fine but sputters when at idle.

The old coils did not meet the Chilton book Specs so I replaced them. The car runs better but the sputtering has returned.

New plugs;new rotor and cap;Hoses checked for leaks and replaced;EGR valve removed and cleaned and re-installed.

The Fuel pump seems to have been hot wired (a wire goes from the ignition to the fuel pump) by the previous owner. This has been fine for two years. I replaced the fuel filter and cleaned out the filter in the pump and carb.

I have not checked out the fuel relay.

There is no electronic box under the passenger seat, so no LED lights .

 

Thanks ahead for any advice

[Alec 720]

I will have to check the repair manual.... however if I had to guess I don't think it matters which coil goes where...

 

Because the coils simply transforms the battery's low voltage to the thousands of volts and has nothing to do with timing...

[datzenmike]

Hopefully you replaced the plugs with NGK recommended by Nissan.

 

Switching the coil to cap leads will not cause any problem.

 

If the truck drives fine it can't be the wires mixed can it? Why would it affect idle and nothing else? You can check the wires by finding the number one intake side plug wire and following it back to the distributor cap. If you stand against the driver's side fender looking in on the cap, the number one wire should be roughly in the 9 o'clock position on the cap. This will be the 1I (One Intake) and the timing order is counter clockwise. The next wire is 2E (Two Exhaust) the rest are 3I,1E, 4I, 3E, 2I, 4E and you're back to the start.

 

If the fuel pump has been jumpered around the relay directly to the ignition I wouldn't bother with the relay.

 

 

You haven't mentioned setting the timing or adjusting the valves.... I would do this next.

[mshore]

I have not yet done valves or timing. The plugs are NKG .

My understanding is that the paired plugs in each cylinder fire at slightly different times to prolong the explosion. I thought the timing of these pairs is so close that a single coil could not recover in time and so two coils were designed in and that their firing order would matter.

But the manual (chilton) does not specify and the group mind seems to think the coils fire at the same time or that it doesn't matter.

 

Thanks for looking into this with me.

Now I will get on with the timing and valves.

[ggzilla]

The truck drives fine but sputters when at idle.

One thing you could do is: don't let it idle. I've been driving mine for 2 months with 1500 rpm idle setting. It drives so nice I haven't bothered to change the setting. I get 29 mpg.

[datzenmike]

I have not yet done valves or timing. The plugs are NKG .

My understanding is that the paired plugs in each cylinder fire at slightly different times to prolong the explosion. I thought the timing of these pairs is so close that a single coil could not recover in time and so two coils were designed in and that their firing order would matter.

But the manual (chilton) does not specify and the group mind seems to think the coils fire at the same time or that it doesn't matter.

 

Thanks for looking into this with me.

Now I will get on with the timing and valves.

 

No. Both plugs fire at the same time.

 

Two ignition sources means that the burn time is considerably shortened. Just like lighting a candle at both ends. This shortens the time at peak cylinder temp/pressure which produces oxides of nitrogen. The timing can be retarded much more than a single plug and more EGR can be run without misfiring.

 

About EGR.... it is only in effect at part throttle to reduce cylinder temps that cause the production of NOx. EGR is not used at idle or full throttle so cannot affect performance.