Roger ... 3/2/2011

1999 GMC C1500 Suburban SLT 8Cyl5.7L - Engine

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engine reves,but does not excelerate the truck

took it to the auto shop and got emisions code po440 the said it was a vacuum leak,I jus put in a new oxigen sensor so I have 2 new oxigen sensors aft of the catalitic converters.It will run good unless I floor it the engin reves but it will not go any faster as if the transmission is slipping.however it runs great uless I floor it at any speed.

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• 
  Bobby 3/2/2011

  P0440 is an evap system leak. the gas cap might not be on the vehicle or sealing correctly that is what usually causes this code. but it could still be something in the evap system leaking.
  
  Next the problem with excellerating. So why did you replace the two oxygen sensors? If it feels like the transmission is slipping most likely it is check the transmission fluid level, then next would be to take it to a transmission specialist to have it checked if it is the transmission not much they can do except rebuild it probably to get it working correctly.

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• 
  J and K AUTOMOTIVE TOWING AND REPAIR 3/2/2011

  hi BOBBY like to add to the p0440
  
  A code P0440 could mean one or more of the following has happened:
  
  * The gas cap is not installed or working properly
  * The purge solenoid has failed
  * The canister is plugged and not working properly
  
  Possible Solutions
  
  With a P0440 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:
  
  * Remove and reinstall the gas cap, clear the code, and drive for a day and see if the codes come back.
  * Inspect the EVAP system for cuts/holes in tubes/hoses
  * Inspect for damaged or disconnected hoses around the Evap purge solenoid
  * Check and/or replace the sensor
  * Check and/or replace the purge valve
  * Have a professional use a smoke machine to detect leaks
  

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  Short Course 3/3/2011

  Ooooppps, looks like we have the same source, never saw this post of your chief, just saw it when i refreshed im sorry
• 
  Short Course 3/2/2011

  A code P0440 could mean one or more of the following has happened:
  
  * The gas cap is not installed or working properly
  * The purge solenoid has failed
  * The canister is plugged and not working properly
  
  
  With a P0440 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:
  
  * Remove and reinstall the gas cap, clear the code, and drive for a day and see if the codes come back.
  * Inspect the EVAP system for cuts/holes in tubes/hoses
  * Inspect for damaged or disconnected hoses around the Evap purge solenoid
  * Check and/or replace the sensor
  * Check and/or replace the purge valve
  * Have a professional use a smoke machine to detect leaks
  

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