drew125

My car is skipping and hesitating while driving and accelerating and just at idle. I have changed my coil pack, the egr valve, the fuel filter. And to top it all, it is throwing only one code, P0455 (Large Evap leak). No misfire codes, no sensor codes, nothing. Any ideas on the cause of this?

BabyGT

A large evap leak will be a vacuum leak in your evap system, a large leak will cause your car to run like crap, go over the entire emission system and check for leaks in any hoses and gaskets.

drew125

Is the evap system different from the vacuum system?

TfcCDR

The evap is connected to vacuum.

That's your charcoal canister, hooked up to the fuel tank vent. The vacuum draws gas fumes to the canister so they are absorbed and then sucked into the engine rather than just venting the fumes out to the world.

PNYXPRESS

The charcoal canister is in the rear of the car and vents to the atmosphere. It could be the purge valve that is stuck open causing that code.

drew125

Would this cause the problems i am having?

PNYXPRESS

Possibly, depends on how important the evap leak detected is to the car operating.

My wife's corvette had a large evap leak code for the fuel vapor purge valve stuck open and it didn't affect the perf at all, just triggered the CEL.

drew125

If a hose has a leak and the valve is stuck open, would that not allow air into the combustion chamber un-regulated?

drew125

I have found the problem. Its my spark plug wires. at night the wire has a spider web of arcs to the block. At least 2 of the 6 wires are doing it; possibly 3. On the coil pack side, the wire is sold white from the energy leaking out. I wont know for sure for about 2 weeks. I will post the results then.

BabyGT

2 weeks?? No parts stores had plug wires any closer than 2 weeks? Well ain't that just a geographical oddity!?