auto 86 na rough idle in closed loop need help asap.

[jaredz31]

hi im new to the Nissan scene. i just traded my wife my truck for her Automatic NA 86 z31. i love it have big plans for her. any way i am a mechanic i work on Chrysler products and typically i dont work on any thing older than 2000. i now know how lucky we are to have obd2 i am lost and need some help.it starts fine but after it idles for a few minutes it starts misfiring. i have never mess with vacuum lines in my live but i dont think there is a leak. i have done my basics and cant seem to resolve the rough idle any suggestion on where to begin? anything will help.

[mizagyu]

Try disconnecting the oxygen sensor and see if that helps any. Other than that, potentially one of the vaccuum solenoids is stuck, or leaking, or vaccuum hose is broken.

For instance, the fuel pressure regulator solenoid opens after 30 or so seconds after starting. Could have a busted hose there. Or, now that i think about it, the fpr itself could be leaking and when that solenoid opens it may just be sucking fuel through the vaccuum lines.

If check those first based off what you say its doing.

[Dunkine]

If it's just misfiring on one cylinder, you can pull plugs and figure out which one and start tracing that way. Make sure you blow out around the plugs before pulling them.
If not just one, double check vacuum hoses, almost all of the hoses on the 89 I bought were like this...

[jaredz31]

thanks i will definitely check those out