Does my 2002 Mazda Protege5 have an EGR Valve Problem?


#1

Whenever I fill up my gas tank, about 5 miles into the new tank, my car begins to buck and jerk around…it feels as if I were just pushing in the clutch over and over again…much like when someone is first learning to drive stick. In addition, when i stop and allow the car to idle, the rpms will drop and the car will stall. This only happens when I fill up the tank and after I put about 15-20 miles on the fresh tank, the bucking and the stalling stops and the car performs well.

One other interesting piece of information… there seems to be no pressure in the gas tank. When i remove the cap, I do not hear the pssssh sound of the air being released.

My mechanic is puzzled but believes the problem may be with the EGR valve. The car passed the California SMOG test just over two weeks ago. If the EGR valve was the problem would it still pass?

As always, any help would be appreciated!


#2

You might want to check to see if there are any stored error codes in your car’s computer. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code not just their translation into English and post it back here. It likely will have a format like P1234.


#3

No, there is no connection between the EGR and the Evap system. The EGR ( Exhaust Gas Recirculation) simply allows exhaust gasses into the intake system. This helps reduce the formation of NOx and SOx gasses in the exhaust.

The Evap system uses vacuum from the engine to manage the fuel vapors from the gas tank and fuel system. This system prevents raw hydrocarbons from being released to the atmosphere. If the tank is not under vacuum, there must be a leak somewhere in the evap system.

A leak could cause the symptoms you have, since this sounds like a classic vacuum leak.


#4

Pardon me. I just re-read the post. This sounds more like a contaminated evap system. Do you ‘top off’ the tank when you fill it up? This could let liquid gasoline into the evap system, contaminating the charcoal canister. Then, it could run way too rich, as the system tries to purge the contamination.

In these newer cars, do not top off the tank.