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View Full Version : Cleaning out my EVAP System -- Engine Flood @ Gas Up and Stuttering on Turbo



exallium
02-22-2016, 12:03 PM
So, I'm pretty sure my EVAP system needs a good solid cleaning.

Here are my symptoms:

When the turbo spins up really high, my engine stutters. It doesn't misfire (no misfire code) but it definitely chokes.
When I gas up sometimes, the car won't start for up to 10 minutes
I have an EVAP Insufficient Vaccuum code on my reader


Reading around, I'm thinking that this could be primarily due to having a very dirty or perhaps even malfunctioning purge control valve. I'm planning to disconnect it this weekend and give it a good spray down and cleaning with Brake cleaner. My thought is that my car either can't suck in enough air or can't expel the fumes fast enough when the turbo kicks way up and it chokes itself.

Does this sound like a sane cause for my symptoms, and a sane solution? Any other input?

Davdraco1
02-22-2016, 01:56 PM
Can you delete the system? Does your state allow that for inspection?

Spectre1130
02-23-2016, 07:37 AM
So, I'm pretty sure my EVAP system needs a good solid cleaning.

Here are my symptoms:

When the turbo spins up really high, my engine stutters. It doesn't misfire (no misfire code) but it definitely chokes.
When I gas up sometimes, the car won't start for up to 10 minutes
I have an EVAP Insufficient Vaccuum code on my reader


Reading around, I'm thinking that this could be primarily due to having a very dirty or perhaps even malfunctioning purge control valve. I'm planning to disconnect it this weekend and give it a good spray down and cleaning with Brake cleaner. My thought is that my car either can't suck in enough air or can't expel the fumes fast enough when the turbo kicks way up and it chokes itself.

Does this sound like a sane cause for my symptoms, and a sane solution? Any other input?

My understanding is your purge valve only releases gas vapor from your gas tank. I don't think it would cause an issue such as you are experiencing. You can leave the EVAP system completely disconnected and it will only throw a code, not cause your car to run funny.

Your engine does not pull much air from that line, only when it is purging does it suck in the fumes. So it would not be robbing the engine of any air. Your turbo is not connected to the EVAP line. Your EVAP only connects into the suction side of your turbo, so your turbo would not have anything to do with it.

I actually just found today that I had been driving with my EVAP system plugged (I had my check valve in backwards) for 3 years and I did not notice anything other than the code.

EDIT: You may have a vacuum/boost leak. Did you recently do ANY maintenance to your car before you noticed this issue? Also do you have any modifications done to your engine?

ricekikr
02-23-2016, 10:22 PM
To test. Unplug the evap and block the hose that goes to the intake.

A leaking evap would flood engine at lower rpms. I've seen them vary from rough idle to stalling. Not sure how it affects boost.

Wrath And Tears
02-24-2016, 11:04 AM
The Evap system only works under certain load conditions, boost is not one of them. It is really only at idle or stead cruise that the EVAP system works. A "leaking" EVAP is the same as unmetered air entering the engine, so stalling and idle hunting can be normal symptoms.

Your issue under high rpm (I assume that is what you mean by turbo spins up really fast....) is most likely a misfire, might just be soft enough to not set a CEL. Coils and spark plugs are the most common culprits for boost misfires.

exallium
02-26-2016, 05:31 AM
Can you delete the system? Does your state allow that for inspection?

I'll have to check provincial guidelines.


My understanding is your purge valve only releases gas vapor from your gas tank. I don't think it would cause an issue such as you are experiencing. You can leave the EVAP system completely disconnected and it will only throw a code, not cause your car to run funny.

Your engine does not pull much air from that line, only when it is purging does it suck in the fumes. So it would not be robbing the engine of any air. Your turbo is not connected to the EVAP line. Your EVAP only connects into the suction side of your turbo, so your turbo would not have anything to do with it.

I actually just found today that I had been driving with my EVAP system plugged (I had my check valve in backwards) for 3 years and I did not notice anything other than the code.

EDIT: You may have a vacuum/boost leak. Did you recently do ANY maintenance to your car before you noticed this issue? Also do you have any modifications done to your engine?

We did a complete engine swap about a year ago. The only mod I can think of is that I have an aftermarket boost meter attached into the lines.

Maintenance was only after I started noticing the issue. I swapped all of the plugs a few weeks ago. Haven't done the coils yet.


The Evap system only works under certain load conditions, boost is not one of them. It is really only at idle or stead cruise that the EVAP system works. A "leaking" EVAP is the same as unmetered air entering the engine, so stalling and idle hunting can be normal symptoms.

Your issue under high rpm (I assume that is what you mean by turbo spins up really fast....) is most likely a misfire, might just be soft enough to not set a CEL. Coils and spark plugs are the most common culprits for boost misfires.

Gottcha. So it's probably a bad coil. It's too bad it doesn't set the CEL =P However, I do think that piston 2 misfired at one point and we swapped in a spare coil we had on hand off the original engine.

Maybe my first step is to replace P2 coil with the new ignition coil sitting in my trunk...

Avant Nate
02-26-2016, 06:40 AM
The Evap system only works under certain load conditions, boost is not one of them. It is really only at idle or stead cruise that the EVAP system works. A "leaking" EVAP is the same as unmetered air entering the engine, so stalling and idle hunting can be normal symptoms.

Your issue under high rpm (I assume that is what you mean by turbo spins up really fast....) is most likely a misfire, might just be soft enough to not set a CEL. Coils and spark plugs are the most common culprits for boost misfires.

The evap system still pulls vacuum under boost through the tip.
I suggest the OP tests his check valves, easy enough just blow through him. The hard warm start may also be due to a faulty CTS.

Spectre1130
02-26-2016, 11:17 AM
Which coils are you using? The old style or the new style? I found my old style on the AEB were junk.

If you changed your plugs, you may have too large a gap and could be seeing "spark blowout" when you hit higher boost. The higher psi in the combustion chamber can prevent a spark across a wide gap.

EDIT: You can also pull your spark plugs and see if one is being blackened by a poor burn. That will help to determine if you a misfire too.