Jim Grant's Tech Tips
Honda Accord EX, Unfixable Computer Codes
My ’96 Honda Accord EX has a MIL that reads these
codes; P0301, P0302 and P1300. I've been doing the process
of elimination by replacing spark plugs, plug wires and
rotor cap, the rotor itself is still good. I even replaced
the PCV thinking it could help. I put some fuel injector
cleaner hoping that could help clean the fuel injectors.
The thing about it is, the car runs great! No hard starts,
no hesitations, no smoke on exhaust, it just starts and
goes. But, the light still comes back on after I clear it
with the scanner after I replace something. I've asked folks
and checked online forums for similar problems and so far
I have yet to get the problem solved..
the funny thing about those computer misfire codes, an engine
can seem to be running just fine but if the computer isn’t
happy with what it is seeing, it gets fun. It sounds as
if you’ve covered most of the basics and commonly
known reasons. But, if replacing all those parts didn’t
reach the end goal you know your not dealing with the norm.
You should know that other items can set misfire codes that
would at first glance have not a thing to do with the ignition
or fuel system. One item that would be helpful is if your
code reader has freeze frames you’ll want to look
at that information to see just when and what condition
the misfire codes are set in. At low RPM and engine load
items such as idle air control valves, manifold pressure
sensor or EGR valves can set misfire codes. Fuel pressure
and delivery issues will tend to set codes when accelerating
or at higher speeds. Then carbon deposits can create another
misfire condition. That’s just some of the fun you
can have when something other than ignition issues are setting
misfire codes. Computers will have you chasing your tail.
Information and a different strategy is called for when
the codes just keep coming back and nothing seems wrong.