# 1987 300ZX NA: Intermittent stalling at any speed/idle



## dJohnn (Feb 19, 2010)

There is an intermittent loss of spark...
The engine will cut out at any time, it does not matter if it just idling, waiting at a stop and go light, city driving or on the freeway. There have been times on the freeway when it cuts out that it will cut in and out several times in a row (with the pedal depressed). It might stay running at those times or it might not stay running. Then it might start right away or it can take a few minutes before starting again. All electrical systems are working when this happens (headlights, stereo, gauges, horn, etc.) and the starter cranks.
I have checked a lot of components or straight out exchanged them.
I may have gotten lucky one time when checking the ECU, there was a code read out, '21', i.e., there is a problem in the primary ignition circuit. The next read out was a '44', i.e., no system malfunction.

This is what I know: 
_There is an intermittent loss of spark, it is before the distributor._ When I have taken the coil wire off the distributor cap, checking for a spark that way, some times there is no spark, other times there has been spark.

This is what I have done, hopefully the following areas can be ruled out:
I replaced the fuel pump, fuel filter, rotor, spark plug wires (distributor cap is almost new), checked the engine compartment harness connections, new plugs, air filter, battery & new cables, new coil, the oxygen sensor is OK, no discernible vacuum leaks, timing is set right, the idle mix is a little rich, the fuel pump pumps, checked the fuel pressure after the fuel filter and got the correct pressure readings, the fuel lines are routed properly, fusible links are okay, plus I have swapped out these units: fuel pressure regulator valve, EGR valve and control solenoid, PTU (ignitor), air regulator valve and throttle valve switch. 

What in the ignition circuit, between the ignition key and the coil, is left to check? What have I missed? (since there is no spark at times from the coil wire I am ruling out the CAS, the problem is before that).
How do I check the relays in front of the engine compartment wheel well on the passenger side?
There are some relays next to the battery, same thing, how do I check those?
There is the pressure control regulator module under the battery tray, anyway to check that (if that could be the problem)?
I have not done a thorough inspection of the wiring going to the coil. It looks okay and the connectors are in good condition.

I thank you for any information you can give me on this. 
This is into the 3rd week of checking this problem.

dJohnn


----------

