1989 SE with a VG30.

Can someone guide me on how to do an engine diagnostic????


i'm looking at the Haynes book and its no help.

 

well you need to tell us what the engines doing or not doing before we can tell you how to diagnose it

 

"Check Engine" is on but the car is running fine though.

Btw...the procedure i was thinking is via the ecu.

 

Go to the Haynes Manual section on Emissions, and at the back of it, it should show you how to read your ECU. If not, go to AutoZone and get the Code Scanner that is available for Nissan, Honda, and Toyota.

When the check engine light is on but the car is running fine, it is usually an emissions thing going on. Check your PCV valve, your EGR valve, and your O2 sensor. Those are the usual culprits.