Mysterious small green cap and a chugging Stang

M

mickn8r65

New Member

Aug 20, 2018

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1

80016

Aug 20, 2018

#1

• Aug 20, 2018

• #1

Hello All,
First post so please be kind
I have 2003 Mustang manual transmission with a V6. I was looking for the AC recharge port when I came across this little green cap:
View media item 13797
I must have messed with it just enough to cause the car to chug violently in first gear. Less so in second and not at all above that. Any help on what it is, how I caused the problem and what I can do to fix?
Thanks in advance!!

 

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wmburns

SN Certified Technician

Aug 14, 2009

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204

Houston Texas

Aug 20, 2018

#2

• Aug 20, 2018

• #2

The green cap is the test port for the EVAP system. So if you messed with it and now have driveability issues it seems to me that you have created a vacuum leak.

NOTE, the EVAP test port has a left hand thread.

 

M

mickn8r65

New Member

Aug 20, 2018

3

0

1

80016

Aug 21, 2018

#3

• Aug 21, 2018

• #3

Thanks for the help. it looks like a valve stem on a tire. Any ideas on how to ID the problem and fix?

 

wmburns

SN Certified Technician

Aug 14, 2009

5,892

514

204

Houston Texas

Aug 21, 2018

#4

• Aug 21, 2018

• #4

Spray a lite mist of water on it to see if you can hear the vacuum leak. Once found, fix the vacuum leak.

NOTE: the EVAP system is pressurized only to 0.5 PSI. So if you applied any high pressure air to the EVAP system you have likely blown a seal some where in the EVAP system.

 

Last edited: Aug 21, 2018

M

MattMan02GT

Active Member

Jul 24, 2018

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Albany, NY

Aug 22, 2018

#5

• Aug 22, 2018

• #5

When you say messed with it, what did you do? Just take the cap on and off, or did you try to fill that line with coolant somehow?