Those codes are all pointing at a related issue. A/F ratio falling out of range, heater elements within the O2's out of temp range, EGR sensor or exhaust gas temp falling out of range, etc. There is a few areas to consider...
Was any work recently done to the car that may have triggered this? When was the last time you replaced the O2 sensors? Check the O2 connectors and wiring to make sure one of them hasn't contacted the exhaust or melted. Any exhaust leaks especially before the cats? When was the last time you performed an induction service and cleaned the intake, TBs, IAC, etc? The EGR and IACV love to get carbon buildup over the years and can affect flow, similarly can happen to the vac lines to the factory wastegate control solenoid. You mentioned the car felt like it was still running well, so no idle RPM fumbling, hanging, stumbling, etc? Are you running an aftermarket boost control solenoid or OEM? Sorry for the load of questions, but need a bit more to go off of to help point you in the right direction.
Even though the vehicle has considerable low mileage, it's still 30 years old. If it's kept in a garage it tends to handle the elements better than sitting out in the external environmental conditions and will need more routine maintenance and care regardless if it's being driven or not. (i.e. 60K / 120k maint w/ timing belt)
By
protoj ·
Well this afternoons mission was to remove the AIV andPVRV systems, I didn't bother with a write up as there are a few out there and the one i used was this it was bang on made it very easy. http://forums.nicoclub.com/how-to-delete-your-aiv-s-90-300zx-n-a-t473354.html
Heres my pile of junk..
And with that gone my car suddenly doesn't leak air in anywhere as bad as it was and will actually hold a steady idle..
Just a small one to find now but i can drive it now ... well once i find the small water leak at the back of the engine :laugh: