Cel codes : a few questions

[enduro]

96 V6, MTX, 100k miles

Got 2 codes that came up on a recent test the 0420 and a 0303.
The car runs good and gas mileage is OK

Anyhow the 0420 I'm convinced is a false code. Can the computer be reflashed to reset the parameters for this code? Or, are MIL eliminators my only option.?

The 0303- Engine misfire cylinder 3, checked wire - resistane within spec, checked coil continuity check specs are 12.8 to 13.1 range , slightly out at 13.4 , but I think the - 2 C temp may have skewed that # slightly. the spark plug (4 months old)appeared OK, gap was OK, slightly black but electrode was clean and proper color.

Anyhow , should I just assume the wire is the problem and replace them all or is there anything else I should check?

 

[Tony2005]

96 V6, MTX, 100k miles

Got 2 codes that came up on a recent test the 0420 and a 0303.
The car runs good and gas mileage is OK

Anyhow the 0420 I'm convinced is a false code. Can the computer be reflashed to reset the parameters for this code? Or, are MIL eliminators my only option.?

At 11 years and 100K miles, I doubt the reflash will do you any good. It is probably past its "band" of limits. Yes, I would suggest the mileliminators unless you want to put new precats in. But as you suspected, it is probably a false code. Fix the P0303 issue first and see if the P0420 comes back later.

The 0303- Engine misfire cylinder 3, checked wire - resistane within spec, checked coil continuity check specs are 12.8 to 13.1 range , slightly out at 13.4 , but I think the - 2 C temp may have skewed that # slightly. the spark plug (4 months old)appeared OK, gap was OK, slightly black but electrode was clean and proper color.

Anyhow , should I just assume the wire is the problem and replace them all or is there anything else I should check?

At 100K, you may as well replace the SP wires as a maintenance item. Now the 0.3 out of range ignition coil is most probably the issue. That would be the first thing I would replace if I were you.

 

[projectSHO89]

Resistance checks of SP wires is usually a waste of time except to verify they're not open. Since your meter is only using up to 2 volts DC to check the wire, it really can't tell you much of interest about how it performs when it has to conduct (and constrain) 20-40Kv during each spark event.

Verify that you used either a Motorcraft or Autolite plug. Replace the affected plug wire (or the whole set) using a quality replacement.

The P0420 indicates that the computer thinks the cat is chemically dead or dying. There is no reflash available for the 96. Use a graphing scanner and compare the upstream vs downstream O2 sensors to observe whether the precat is working or not. Without this visual confirmation, you will have to either rely on the PCM and its programming or take a flyer based on the suggestion of someone on the internet.

Steve

 

[enduro]

Thanks for the replies.

Yes, motorcraft spark plugs. 2nd owner of car, it's possible the wires are still the originals.

I think I'll just replace all the wires, and go from there.