Blazing Boss

Hello everyone, I am new to this forum. I have a 2012 Boss 302, very similar to the 5.0 Coyote motor.

I have TWO main issues at hand:

1. Idle surges down below 500 RPM filling up gas / sputters then recovers on its own.

2. On COLD STARTS only, the RPM doesn't shoot up as high as before. It is as if the engine is already partially warmed up (P.S. nothing to do with weather).

***other than these two problems, NO other problem exists at any time the car is running or stopped

***also, I DO NOT have a CEL or any codes both KOEO and KOER (key-on engine off / key-on engine running diagnostics) via Ford IDS

Did a little research on the fuel system, and looked into the purge valve.

Saw an article about purge valve problems "a stuck-open purge valve can cause difficulty starting right after refueling at a gas station: for the first few seconds the engine may run rough and stumble."

Problem is I do not have any CELs or codes, but the car is manifesting the above two problems I stated.

What could be the problem? Certainly, there is a problem although the CEL is not throwing any codes. Could it be that the purge valve is in the process of failing? Could the CEL show when the purge valve finally fails?

What else could lead to the 2 issues I have other than the purge valve?

I already performed KAM reset and all is well, idle is smooth at all times except when I go to fill up gas. It has got to be something in the fuel/ignition system.

jwog666

if the evap monitor passes and doesnt set a code, then there shouldnt be an issue with the purge valve or any other part of the evap system. a goes way to check to see if the purge valve is stuck open is to fill the car up, pop the hood and remove the vapor line that connects to the valve from the tank, start car and see if your concern still exists