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"Air Compressor" Type Sound from Rear of V8 Vantage

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"Air Compressor" Type Sound from Rear of V8 Vantage

 
  #16  
Old 07-01-2012, 01:50 AM
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Originally Posted by irish07 View Post
To me it sounds like the DMTL pump running a check. The system does actually run at times while completely "off". The vehicle has to go through a number of steps (drive cycle for DMTL pump), when this drive cycle is met, the test is performed, weither it be a small or large leak test. The large leak test is usually done while running(how it detects a open fuel cap), the small leak test is usually done while off. If a leak at say 20thou was present on a purge line(small pin hole from some road debris), the DTML would not detect this leak while running for the vapour mangement valve opens/closes while running and fuel level changes and does not stay steady(flat), due to stop-go and corning..so for a small leak, the small leak drive cycle has to be met and vehicle needs to sit while off(soak for time). When the car was just turned off, the large leak test will still continue if it had started and will stop when it finishes(don't have to worry about the battery, it has a protection for that is low voltage is present so the test does not fail)...if you just shut off the car and the noise continued to be heard for 2mins..this sounds like the large leak test was in operation-and continued till finished. If there was a fault with the test, next ignition cycle the MIL light would be on..no fault, no MIL light
Ok; so I've heard the DTML pump run on a few ocassions after shutting down my car. On this last time, the check engine light came on after I restarted the car the next morning. My dash now says "Emissions System Service Required." I am assuming this is probably related to the DTML pump and a fault that was logged? But I am not sure.

Also, when the DTML pump finishes its test, it is normal to smell gas from around the gas cap area? I assume it is from the pressure being released and the fumes being let out. I have not otherwise smelled gas from this car before.

Thanks in advance for chiming in; much appreciated.
 
  #17  
Old 07-02-2012, 11:09 AM
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Originally Posted by macksamus View Post
Ok; so I've heard the DTML pump run on a few ocassions after shutting down my car. On this last time, the check engine light came on after I restarted the car the next morning. My dash now says "Emissions System Service Required." I am assuming this is probably related to the DTML pump and a fault that was logged? But I am not sure.

Also, when the DTML pump finishes its test, it is normal to smell gas from around the gas cap area? I assume it is from the pressure being released and the fumes being let out. I have not otherwise smelled gas from this car before.

Thanks in advance for chiming in; much appreciated.
You should never smell fuel outside the vehicle, the pressure is not released to the outdoors after the test finishes..if after a test finishes, you start the car and get the emissions light+the smell of fuel..you have a evap leak somewhere, could be from the cap or from the DMTL, the water drain hose for the fuel cap area goes near the DMTL pump, if the pump valve doesn't close when it's requested, you will get vapour smells in the fuel cap area also. First thing would be to scan for faults..
 
  #18  
Old 07-02-2012, 12:55 PM
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Originally Posted by irish07 View Post
You should never smell fuel outside the vehicle, the pressure is not released to the outdoors after the test finishes..if after a test finishes, you start the car and get the emissions light+the smell of fuel..you have a evap leak somewhere, could be from the cap or from the DMTL, the water drain hose for the fuel cap area goes near the DMTL pump, if the pump valve doesn't close when it's requested, you will get vapour smells in the fuel cap area also. First thing would be to scan for faults..
Thanks Irish. Just took my car in and the techs said the fault was triggered by the DMTL test. They said there is some valve in my fuel cap that was probably causing the issue. They realigned whatever was causing the issue and told me it's best not to insert the fuel cap into the holder when fueling up as this can cause a problem if I wiggle the cap too much when inserting or removing it from the holder. Apparently these fuel caps are pretty fragile and expensive....$300 and not covered by the extended warranty
 
  #19  
Old 07-03-2012, 07:45 AM
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"it's best not to insert the fuel cap into the holder when fueling up as this can cause a problem if I wiggle the cap too much when inserting or removing it from the holder. Apparently these fuel caps are pretty fragile and expensive....$300 and not covered by the extended warranty "

That's really good to know. I wiggle mine a lot to keep it in place--so I'll stop doing that. Thanks!
 
  #20  
Old 07-03-2012, 10:30 AM
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Originally Posted by dicktahoe View Post
"it's best not to insert the fuel cap into the holder when fueling up as this can cause a problem if I wiggle the cap too much when inserting or removing it from the holder. Apparently these fuel caps are pretty fragile and expensive....$300 and not covered by the extended warranty "

That's really good to know. I wiggle mine a lot to keep it in place--so I'll stop doing that. Thanks!
Awesome, true test is the next day after you start the car..if the engine light doesn't come back, problem solved. If it ever does though come back on down the road, try to remember if you just filled the fuel, this would help you diag the problem faster
 
  #21  
Old 04-19-2018, 09:36 PM
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DTML pump

I had my key in position 2 without engine running and I heard the "air compressor" noise coming from right rear tire area.
Shutting key off turned if off.
A quick search pointed me to this thread.
Since the video link is broken, I sat my phone on the tire and recorded 10 seconds of sound for forum members future reference.

​​​​​​https://youtu.be/e-OIpy4zzKw
 
  #22  
Old 04-20-2018, 04:34 AM
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Originally Posted by 007V8Vantage View Post
I had my key in position 2 without engine running and I heard the "air compressor" noise coming from right rear tire area.
Shutting key off turned if off.
A quick search pointed me to this thread.
Since the video link is broken, I sat my phone on the tire and recorded 10 seconds of sound for forum members future reference.

​​​​​​https://youtu.be/e-OIpy4zzKw
rear right tire is your exhaust bypass motor. Itís trying to create vacuum to close the valves. If itís constantly running, either a vacuum leak or pump pressure switch is toast and motor doesnít know when to shut off. The dmtl is in the left rear and you can barely here it when running..
 
  #23  
Old 04-20-2018, 05:16 AM
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Ryan I thought you had the fuse 22 out to keep you exhaust flap open all the time?? With that fuse out you will not hear that sound as the exhaust bypass motor won't run
 
  #24  
Old 04-20-2018, 05:25 AM
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Thanks Irish, you are correct as usual.
i created the situation by reinstalling the fuse in prep for my "stock" Dyno run.
 
  #25  
Old 04-20-2018, 05:49 AM
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Originally Posted by handyman2009 View Post
Ryan I thought you had the fuse 22 out to keep you exhaust flap open all the time?? With that fuse out you will not hear that sound as the exhaust bypass motor won't run
Yep, to be sure I pulled the fuse again and it shut off.
Something else to check out when the Vantage is on the hoist...
 
  #26  
Old 04-20-2018, 05:56 AM
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After installing the headers and 200 cells cats you will see if you need that fuse out or not... I am looking forward to installing those new cats and tune
 
 
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