I have a 97 HX with same problems a few years ago. The exhaust passages were clogged up. You have to remove the fuel rails to access the top of intake manifold. You will see about 8 bolts that holds down a plate to gain access to the plugged up passages. Also, I still have my original primary O2 sensor, the secondary sensor was replaced. I don't rememember the CEL, but it said something about insufficient levels. The misfires was a dirty IAC. I had about 220,000 miles when I had all these problems.

 

I recently cleaned my IACV and while my CEL stayed off for much longer than normal, it returned the other day. To summarize my problem, I have the following issues with my '97 Civic HX with 168K on the engine:

• Fast idle at initial startup (idle around 2,000 RPM)
• Low, rough idle after the engine warms up (around 600 RPM)
• Bouncing, or "searching," idle after letting off the gas at normal cruising speed.

Unfortunately, I haven't probed the ECU to determine what the code is at this time, but I'm betting that it is still the engine misfire code that was causing the variety of other problems (EGR insufficient lift error and primary O2 sensor error) that I described in earlier posts. The service manual says to check fuel filter next. Do you think this is worth my time or could something else be happening?

 

I thought that only Accords and Preludes had EGR valves and EGR intake ports with plugs that need to be cleaned. My Civic with a D16, doesn't have an EGR valve.

 

Only the Civic HX model with the D16Y5 engine has the EGR system.

 

Pull the CEL codes.

 

In summary, it WAS my IACV that was causing the EGR valve code, and the O2 sensor code. After cleaning it my idle returned to normal (after a few weeks) and my CEL has stayed off! Thanks a million to everyone for their useful advice.

Cheers,
Dan

 

Well i have a 97 civic dx with the d16y7 and i have the p0401 egr code lol but im sure theres no egr located anywhere, so what could it be since theres no egr valve with an egr code?

 

D16Y5 ECU swap?

 

Yes if you get a code which should not exist for your engine / transmission setup, that means you must have the incorrect model ECU installed.