1992 Honda Accord Engine Runs Rich When Engine Temp is Normal

Reader Question hi Austin,

just a quick question on 1992 accord w/2.2, and something that’s a real brain teaser. after about 10-20 min or running when engine reaches full operating temp engine seems to run approx. 500 rpm higher/richer, with nothing else showing fault or error codes. although, pulling the ECU reset fixes it temporarily, but symptom returns. i hope with your years of honda service and expertise you have seen this very same thing, any idea?? thanks for your time.
Thanks,
Raf

Hey Raf,

Do you own a copy of Alldata online repair manuals?

Auto repair manuals

You will need some diagnostic reference material for component testing and they have some good stuff. I would look at what is taking over as the engine reaches full operating temperature and see what is out of scan. A few things come to mind

1. Bad or lazy Oxygen sensor
2. Faulty coolant sensor
3. Problem with thermostat
4. EGR problem or vacuum problem
5. Vacuum leak under the hood in a vacuum hose or gasket
6. Ignition timing problem

Blessings,

Austin Davis