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· Registered
2018 STi
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158 Posts
Discussion Starter · #1 ·
Id like to say i know what the problem with my car is but i have no clue at all. I could guess and start replacing parts but it could be several things, i'm just hoping you could help me narrow it down.

Symptoms:
CEL - P0440 code (Evaporative Emission Control System)

Accelleration - in 1st and sometimes 2nd gear it will randomly stutter for a second

My guesses are, could be bad injectors (car has 135,000 miles on it w/o being replaced), or possibly something to do with the fuel system b/c of the P0440 code.

When it stutters it just feels like all of a sudden the gas gets cut off or theres a pocket of air in the gas line. Its like if you were to take a hose and turn on the water, it flows nicely but then if a car rolls over the hose it loses pressure for a split second. Kinda feels like that. Any ideas guys?

- thanks jay
 

· Registered
RIP 2000 2.5RS, 1999 RS
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625 Posts
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

There is a purge solenoid and valve in the vapor canister that can fail preventing the fuel tank from maintaining pressure
 

· Registered
2018 STi
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158 Posts
Discussion Starter · #5 ·
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

There is a purge solenoid and valve in the vapor canister that can fail preventing the fuel tank from maintaining pressure
Where is the vapor canister? is there anyway to check if these parts have done its time and are gone?
 

· Mobile Diagnosis Guy
97 Impreza L
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5,319 Posts
the vapor canister in your car should be under your rear bumper under the passenger side taillight. Thats where it is on GD WRXs. The evap control system has nothing to do with the injectors.

The evap systems collects and stores hydrocarbon vapors and releases them into the engine at designated times. Also, at designated time, this system put itself under vacuum and then closes the system to check for leaks. If the vacuum begins is fall, it knows by looking at the evap pressure sensor and it will store a trouble code. More likely than not your evap purge solenoid is stuck open and you are constantly drawing in whatever is in the system. When all of the hydrocarbon vapors are drawn out, it will begin to draw in fresh air trough the normally open vent solenoid, this will cause the car to run lean...causing your hesitation problem.

A dealer could look at your fuel trims and see that the PCM is adding fuel to diagnose this. They could also unplug your purge solenoid and blow through it to check it. It is a normally closed solenoid and should not let air through.
 

· Registered
2018 STi
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158 Posts
Discussion Starter · #9 ·
the vapor canister in your car should be under your rear bumper under the passenger side taillight. Thats where it is on GD WRXs. The evap control system has nothing to do with the injectors.

The evap systems collects and stores hydrocarbon vapors and releases them into the engine at designated times. Also, at designated time, this system put itself under vacuum and then closes the system to check for leaks. If the vacuum begins is fall, it knows by looking at the evap pressure sensor and it will store a trouble code. More likely than not your evap purge solenoid is stuck open and you are constantly drawing in whatever is in the system. When all of the hydrocarbon vapors are drawn out, it will begin to draw in fresh air trough the normally open vent solenoid, this will cause the car to run lean...causing your hesitation problem.

A dealer could look at your fuel trims and see that the PCM is adding fuel to diagnose this. They could also unplug your purge solenoid and blow through it to check it. It is a normally closed solenoid and should not let air through.

what can I myself do to fix this problem? i would love to avoid lettin the dealer do n e thing with my car so i dont get raped for money. it def sounds like you know whats going on with my car b/c what you just said is to the T of what is happening, this would also cause me to blow through gas and my car is def running lean. please let me know how i can fix this problem and what parts i may need. thank you so much again
 

· Mobile Diagnosis Guy
97 Impreza L
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5,319 Posts
First thing i would check is the purge control valve. It should be located under the intake manifold with two lines going to it. Its wires are yellow/red and white/red. take that out and blow through it, if you can. Replace it.

The dealer probably had a EVAP testing smoke machine, which is a great tool. Easily finds leaks and blockages.

Oh and check your gas cap too. thats a common problem ,it being loose or not seated correctly.

Also found something on nasioc stating there is a recall and that this cause will sometimes come on without fault and that the ECU needs to be reflashed.
 

· Registered
2018 STi
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158 Posts
Discussion Starter · #11 ·
First thing i would check is the purge control valve. It should be located under the intake manifold with two lines going to it. Its wires are yellow/red and white/red. take that out and blow through it, if you can. Replace it.
is that also known as the duty solenoid? it has 2 vacuum lines going to it with an electrical plug that has 2 wires? its located under the intake manifold on the left hand side?
 

· Registered
2002 2.5RS BRP
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2,880 Posts
I have the same car and had the same problems, check your belts and your clutch. My clutch would shutter pretty bad in 1st and sometimes 2nd toward the end of it's life, and I had my belts tightened to fix the split-second power loss you're talking about. No big deal really.
 

· Mobile Diagnosis Guy
97 Impreza L
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5,319 Posts
is that also known as the duty solenoid? it has 2 vacuum lines going to it with an electrical plug that has 2 wires? its located under the intake manifold on the left hand side?

ive never heard it called that but its a possibility. check the colors of the wires to be sure. There is most likely another solenoid under there with two lines that controls the EGR operation, that has a better chance of being called a duty solenoid.
 

· Registered
2018 STi
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158 Posts
Discussion Starter · #14 ·
ive never heard it called that but its a possibility. check the colors of the wires to be sure. There is most likely another solenoid under there with two lines that controls the EGR operation, that has a better chance of being called a duty solenoid.[
EGR?

I have the same car and had the same problems, check your belts and your clutch. My clutch would shutter pretty bad in 1st and sometimes 2nd toward the end of it's life, and I had my belts tightened to fix the split-second power loss you're talking about. No big deal really.
i def know that at least one of my belts is loose b/c it chirps when i shift and the A/C is on. on the 2nd note of that, my clutch is good. other than the stupid throw out bearing that chirps like a freaking bird when i idle
 

· Registered
97 Brighton, 4x4
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2,573 Posts
Dude, I have every same exact problem you have! This is nuts. I have the hessitation, the code, the ac chirp, and no idea what to do. Have you found the evap purge solenoid yet? I'm going to figure this out because It's pissing me off. even the same miles!
 

· Registered
2018 STi
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158 Posts
Discussion Starter · #17 ·
i have a feeling the purge solenoid is the same thing i'm talking about. and if it is, it def makes sense b/c i broke one of the nipples off of the solenoid and had to jimmy a tube over the broken part to keep the vacuum pressure up. but i'm gonna replace that i think and see what happens.
 

· Registered
2018 STi
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158 Posts
Discussion Starter · #20 · (Edited)
First thing i would check is the purge control valve. It should be located under the intake manifold with two lines going to it. Its wires are yellow/red and white/red. take that out and blow through it, if you can. Replace it.
soo i figured out the purge control valve is what we are both talking about 96Imprezadent. you told me b4 if i can blow air through it then it is bad, well i can't blow air through it... any idea what the next problem could be?
 
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