I have a 97 Accord 2.2 Vtec that unlike most MISFIRE threads runs smooth and accelerates strong. I get a CEL about every 80 - 100 miles (sometimes less) but I can never set all my ECU readiness tests to pass emission test. I get the same P0301,P0303, P0304 every time. Sometimes a generic P1399 code. But Never a cylinder 2 P0302 code.


I cleaned the EGR plate, installed new dist. cap, spark plugs, and plug wires. New air filter. Checked the timing. I pulled and cleaned the injectors externally. The timing belt & water pump are new.





Could this be a bad ground or noise issue?

My inspection station tells me just drive on the expressway for 20 minutes @ 50 to 55mph.


Evaporative System test & Oxygen Sensor monitoring never seems to complete.


I was thinking of swapping cyl #2 injector with cyl#1.
Why doesn't #2 misfire?


I didn't check fuel pressure because I don't have the right fittings, but the engine has plenty of power...


Thanks in advance for advice

 

There are some basic items that you should try.

I would disconnect the battery and clean all ends of both battery cables (clamps, bolts, and eyelets) with a wire brush or sandpaper. I'd do the same on all of the grounds you can find in the engine bay. G101 is an important one, so definitely clean it. It is on the driver's side of the upper intake manifold, see picture below.

I'd take your car to a parts store and have them check the battery and alternator, as this is a free test at most places.

 

I'm wondering if maybe your car is running colder than usual. Perhaps the thermostat is stuck open and not allowing the car to go into closed loop which would explain why the oxygen sensor doesn't ready. The oxygen sensor only reads after the car warms up fully.

 

The battery terminals were cleaned with a battery wire brush tool. Alternator is charging at 14.25V. Coolant temp fan cycles 205F to 215F On OBD.

 

Next thing I would look at considering you have said you cleaned the egr plate is doing a valve adjustment. I'm not sure why those tests aren't readying though.

Did you make sure to clean out the main egr valve port ? Also, and don't take this as a diss but are you sure you did a good job cleaning out the egr plate ? Again, not trying to diss just that would seem to be the most highly probable cause of this.

The only other thing I can think of is that maybe the ecu is bad but that's very rare.

 

I noticed that ECU problems from the 94-97 accords are not a rare, since these are 17-20 year old accords. A bad ECU is still rare, but not like when I first started going on forums dealing with issues from the 5th generation accord.

Check out car-part.com for used ecus from junkyards. I like this site because you can sort by price or distance. You may find a cheap ECU nearby. U-pull-it yards are another good source for parts. You need an ECU from a 96 or 97 EX accord that had the same transmission as your accord.

 

I tested with a 97 LX (non VTEC) ECU and got the multiple misfire codes as well.
I noticed I get codes in the morning when the engine is cold.
I did finally get all the readiness codes completed and passed emissions inspection but the next day got a multiple misfire code.


I'll try compression test & adjust valves next.


Thanks for the advice