Im pulling a PO455 code (gross leak/no flow) would this cause my truck to have a rough idle and rev itself up until it warms up and kinda pop and slightly backfire? And also puliing code PO141

Jerry Koski

• 443 Answers
• Posted on Apr 12, 2009

SOURCE: rough idle, backfire on acceleration

check everything you can under the hood your air intake system all of it especially make sure all clamps are tight .. and make sure all vacuum hoses are good and not cracking or broken or just loose . you might run a little fuel cleaner through a tank of gas too cleaning the engine fuel system up some. just a few ideas.. Jerry

SOURCE: Evap Emissions Leak

This can be because the Gas cap is not holding the pressure. I would start there first.

PAUL MC G

• 1280 Answers
• Posted on Oct 18, 2009

SOURCE: 2000 elantra po455 code evap emission control

Large leak?... Fuel Cap not tight or the wrong one is installed. Also, the charcoal canister close valve may be stuck 'open' AND/OR the purge control solenoid valve may be stuck 'closed.'

SOURCE: Ford Merc PO455 Gross evap leak, could it be gas

gas cap, clean the maf sensor, check for vacuum leaks. i would start with those.

SOURCE: po455 generic evaporative emission system leak

Diagnostic Trouble Code (DTC) P0455 basicly means that the Powertrain Control Module (PCM) does not see any change in the Fuel Tank Pressure Sensor (FTP) when: (A) vacuum is applied through the Purge Control Solenoid or (B) When the system is tested by the leak detection pump.

The code description says "GROSS LEAK/NO FLOW " because the PCM cannot tell if the problem is being caused by a large leak in the EVAP system components or if the problem is that the purge valve is not opening when it is commanded to do so.

The MOST COMMON cause of this code is either refueling the vehicle with the engine running or a fuel cap that is not installed properly. Check your fuel cap and make sure that the rubber seals in the cap are not dammagedor full of cracks. If you find obvious damage to the fuel cap seals, replace the cap. Otherwise, install the cap and make sure it "clicks" when you twist it on. The Malfunction Indicator Light (MIL) (also known as Check Engine Light) will go out in a couple of days if this was the problem. If it does not go out, then the system will need to be diagnosed.

POSSIBLE CAUSES:
> Loose, damaged, or improperly installed fuel cap
> Damaged, cracked or disconnected vacuum/purge hoses or lines.
> Faulty Purge Control Solenoid Valve
> Defective Leak Detection Pump
> Defective FTP sensor
> Defective PCM

This code cannot be caused by circuit failures unless this code is accompanied by other codes indicating circuit failures in one or more of the EVAP system components. In this case, the circuit failures MUST be addressed FIRST.