2001 p0455 ca smog fail

Discussion in 'SN95 4.6L Mustang Tech' started by 01blackvertgt, Sep 27, 2008.

  1. Previous responses requested an inspection for vacuum leaks under the hood. How hard was it to spot the bad hose?

    Try this. Remove the small vacuum line from the EVAP purge valve and verify there is vacuum on the line with the motor running. If no vacuum, consider that the line may be broken or crushed between the EVAP valve and the Throttle body Tee.
  2. Hotcobra do you have the pic? I looked at that and my TB bolts to the intake manifold, I have 2 hoses from the inlet tube (between TB and MAF) and one has a box on it, I really see no way to mount it differently. was your car a 99-04 4.6l engine?

    Thanks for the efforts ;-)
  3. po455

    i can amagine the look on most of the guys faces who have replied...

    how much did you pay him?????????????

    you missed something,,,,if it we me i would pull the 2 hoses going from engine to valve in fender....if the large hose makes hand black change it ...the tiny hose will be plastic ...in your hand try to blow thru hose,than suck...it should be the same both ways just like a straw...a restriction is the opposite a leak,but will affect operation of the unit...

  4. I had him replace the vent solenoid with the wrecking yard one, and then he was running diagnostics with his scanner, the engine had been idling pretty smooth for 30 minutes or so, then it surged, and came back down to 800 rpm. he sprayed carb cleaner all around the engine intake area. it surged big time when he hit around the pcv valve, then it stopped, he tried again with the spray and no surge, my bro went and bought a new pcv valve and we removed the old one. the hose looked fine, except it was cracked and had been taped with electrical tape making it an intermittent leak. this must have been done when thy replaced the engine about a year ago.

    I will check the small vacuum line going to the purge valve tonite for vacuum and replace the purge valve with the wrecking yard one just in case.
  5. he made his money, $60 dlls, he was there for 2.5 hours. he replaced and tested the evap purge valve, ran diagnostics, then when out of the blue it surged, looked for a vacuum leak and found it. I had checked for leaks already Saturday and it must have been really intermittent. you should have seen my and my bros faces.

    I already replaced the 2 large hoses going to the purge valve, yes they where pulverizing. I will next check the small hose.
  6. went to car disconnected small vacuum tube that goes down into fender well to purge valve and noticed that it was NOT in all the way, I started the car and there is a vacuum on the engine side I connected it all the way and erased the code. I will see if I get it again on the drive home.
  7. OK, no codes on the drive home, on the drive to work I got a P0457 pending. I think I need to check all the hoses/vacuum lines in the engine compartment. sounds like the shop that swapped the engine did a poor job.

    does any one have the vacuum diagram for this 2001 4.6l 5 speed gt convertible. also the intake hoses, pretty much all hoses in the engine bay.

    a p0457 is a small leak, it is an improvement over the p0455, large leak.
  8. code

    gas cap is for 457...
  9. 457

    P0457 - EVAP Control System Leak Detected (Fuel Filler Cap Loose/Off) A fuel tank pressure change less than a minus (-) 7 inches of H 2 0 in 30 seconds has occurred after refueling; or there is excessive purge (fuel vapor) flow greater than 0.06 pounds per minute. Fuel filler cap not installed on refueling (storing continuous memory DTC) and "Check Fuel Cap" light may also be illuminated.
    Fuel filler cap missing, loose or cross-threaded.
    Check for missing fuel filler cap or integrity of the cap. If OK, clear continuous memory DTCs and re-initiate EVAP Emission Running Loss Monitor Drive Cycle.
  10. Here's a thought. What if the EVAP Charcoal canister was loaded up with vapor? The large leak would have prevented the "flushing" effect that an EVAP purge performs. What if the problem is actually fixed but more than one EVAP purge cycle is needed to flush out the charcoal canister of gas vapors?

    With regards to finding a difficult vacuum leak. Consider a propane based leak detector. I have never been a fan of spraying carb/choke cleaner all over an engine. The solvents could damage gaskets thus trading one problem for another.

  11. leak

    i do think you got this one nailed...what was added by wmburns was in the code 457...

    i learned just like you are...i have found if the cel is on the code will be right...

    being the code changed is great,,,than no 455 with the 457 is another +

    wish i could be better help on vac hoses...i did copy 2 sections of manual...

    removing intake with engine installed which shows hoses you need to unhook


    engine install


    you can use this to see how the guy did with install
  12. Mr BURNS, should I erase the code and keep driving for it to keep flushing, or just drive it??

    I will still look for more bad hoses in the engine.
  13. Cobra thanks for the pdf's but they take me to a generic acrobat page.
  14. pdf

    i just tried them and they did work,,,i have had times when they are slow to open,,,

    they do need adobe 9 to work...

    sure clear the codes...remember seeing a footnote on the monitor runs during the first 30 mins...take a good easy drive
  15. got them thanks. cleared code, will see if it comes back.
  16. 50 miles and no codes, evap and cat diagnostics not done yet. At this point I am praying and holding my breath.

    It surged a little while in stop and go traffic a couple of times, I do not know if it is because of the canister gases being ingested, a vacuum leak or dirty air bypass valve.
  18. Do you have a source of regulated air? If so, the EVAP system can be pressurized to 1-2 PSI without damage (no more as damage is almost certain). This may be enough so that a large leak can be heard. Another possibility is to use a hand operated vacuum pump on the EVAP purge valve and pull a vaccum on the system. Of course, this may give you a really good grip workout.

    Time how long it takes to for the vacuum to bleed away. It will be necessary to attach the vacuum at the EVAP valve and force the EVAP valve to open. It will be necessary to force the CV vent solenoid to close. Or pull and plug the vent line.

    Another option is to use engine vacuum to draw down the EVAP system. Ground out the LG/BK wire at the EVAP purge valve to force it to close. However, you will need some method to monitor pressure within the EVAP system.

    For the above methods to work, IMO the engine will have to be off. Otherwise I doubt anyone's ability to "hear" the leak as the pressures are so low.

    Finally, if the low pressure/vacuum tests show the system is actually holding pressure, consider the possibility of a false error. If so, the problem will be in the fuel tank pressure sensor (FTP).

    Finally, there is the professional "smoke" test route.
  19. po455

    as to a tool...im gonna assume he has a new style sct with him saying the monitors havent completed...

    i have the old predator,,in data log there were pids for ftp volts and pressure,,,i would plug into my buddys L to see difference in readings and what does happen..than compare to values chart

    would that be any help for him?


    thanks for hanging in there,,most guys disappear...i just looked at my car...i did change the tiny line to a rubber hose...this line had a restriction
  20. If this were my car, monitoring the FTP sensor would have been one of the first things done. This would confirm that the sensor is working and sending reasonable data. Further, it would offer an easier way to monitor pressure within the system.

    I guess I have gotten so used to working posts where the OP doesn't have ODB2 monitoring capabilites (or doesn't want to learn how to use them).

    I think it would be a big help to use an ODB2 scanner to monitor the fuel tank sensor. Perhaps even force a simulated EVAP pressure test by forcing the EVAP purge and CV vent solenoids to close and confirming the vacuum is seen at the FTP sensor.

    Great idea!