I just bought a 1987 Nissan Pathfinder with the z24i motor. It sat in a guys yard for a few years...I drained the fuel, replaced the plugs, coil wires, intake side coil, plug wires, fuel drained and refilled, new fuel filter, intake gasket, bypassed the EGR, and I am not getting any spark from the intake coil...the one with the four pronged ignition module. So it runs good at low power, but after applying about 50% throttle or more the engine dies until the RPMs drop. THe ECU is cutting out the exhaust spark (I think normal) under load and that leaves me with no spark.

1. I am getting code 21 from the ECU
2. I replaced the coil...no improvement, swapped coils, no change.
3. I don't know if the ignition module is the problem..cant swap them as one is three pronged and the other is four.
4. I looked at the wiring diagram and varified 12v and ground to the ignition module...but the other two wires go to the the ECU I believe and that is a mystery to me.
5 The scematic shows four wires coming from the crank angle sensor, wondering if the signal from the CAS is shared for the two coils or could that be the issue. Is that even a possibility...I thought maybe if the exhaust side works, wouldnt that mean the distributor is signalling the ECU properly.

Right now I think its either the distributor crank angle sensor, the ECU or the ignition module.

Am i on the right track? Anyone in the Tampa area have the no how to help me narrow this down...I've bought enough parts (would have anyway) and really just want to diagnose this properly...?
Sincerely,
RC

 

code 21: ignition signal circuit

haynes manual does no justice, this guy from nissanforums had same code/problem, said he had BOSCH plugs and wires, swapped em to NGK i believe and it fixed it....

Not sure if theres much evidence behind that

 

Not so sure about that...when I take the coil wire near a ground and crank the motor, there is no spark, so I believe before I even get to the plugs...there is no spark. RC

 

"check power into your ignition module(4 prong, intake)
check power out
if one side isnt working cause no power going into the module from the ecu, JUMP IT from a 12 volt source. Those coils are just a basic 12 volt setup. Make sure you put power into the module so the module can do whaterver its job is for the coil. You know, just keep the coil pluged in to the module add power to module.
You can even use the power from the other modules plug, cause up stream they share the same power supply anyway."

 

Okay...problem solved! Although there was power to the coil,by the battery there was a pair of wires that came out of the harness...and had a male and female plug that was badly corroded. So I cleaned the wires, cut out the connector and butt spliced the wires together. That must have fed power to the computer or something...because the truck runs like a scalded dog now.

I really appreciate the help! My $500 Pathfinder is now a $2,000 ride :o)