Hi folks,
Three days ago I replaced all four o2 sensors (fun). My SES light went out all by its little self. Nice finally having no error lights on my dash for a change. Before that the SES light was on and blinking now & then and the shop was showing (random misfires) & of course the shuttle valve switch which I replaced and have had no issues since. This AM I hooked up an i930 iCarsoft code reader and all four sensors were fine (I checked every line on all four). SO...
Code P0455 EVAP leak (probably my gas cap? since its not seating well?).
Code P0300 & code P0305. Misfire on cylinder 5. All else seems good. During that 24 hours after the SES light went out it ran fine (best its ever run).
Ideas?

Thanks in advance.
RoadDog
Upstate SC

2001 Discovery II
Using Sunoco 93
117K

 

So, how many miles on the old plugs and wires and what brand and or color are your wires?

 

The cables are black and I replaced all the plugs about six months ago.

 

I would look real seriously at the plug wires, there is not a black after market wire that will hold up in the Rovers engine compartments heat.
You should use only 8 mm silicone wires, I recommend either the STI or Magnacor, both are dark blue.

 

Thank you, Mike!

 

What the hell do you mean a black wire will not hold up under the hood. EVEN DM would not have made such a stupid remark. imposter
Go to kingsborne wire you can get a set of 8mm or 8.5 wires for 25% of the price. And you can get them in black, blue, red or yellow because the color has nothing to do with how they work. Quite a few people on here are running them with no problems

 

Instead of just replacing parts, you could try to check the plug wires first. Try starting the engine and misting the wires with water. If there is any arcing, replace the wires. (Works best at night). If there are no sparks, you can check the resistance in them. Depending on the wires you have, the resistance is usually somewhere between 5-8,000 ohms per foot. So with some simple measurement and math, you can figure out an approximate resistance range. Connect the multimeter leads, one on each end and check, then bend and pull on the wire a little while watching the meter. If the meter shows an open circuit, or you get inconsistent ohm readings, then the wire needs to be replaced.
Also, while you have the wire out, you can inspect it closely for damage.

As far as the P0455 code goes, the only way to really be sure is a smoke test. In this case, there's nothing wrong with replacing the gas cap (they're cheap enough and they can certainly go bad), especially if you suspect it's not sealing. Beyond that, you can take a look under the truck and make sure there isn't a broken or disconnected hose or tube somewhere in the evap system. This code is for a big leak, which is often much easier to find than a small one.
Good luck, I hope you get it figured out.