2004 Kia Optima EVAP Gremlins

Jordan Owner/Technician Washington Posted   Latest   Edited  
Resolved
Emissions
2004 Kia Optima LX 2.4L (6) 4-spd
P0455 — EVAP System Leak Detected (large leak),
C/S Intermittent Power Loss

Good Morning Everyone.

Customer dropped off a 2.4 2004 Kia Optima complaining of intermittent power loss/rough idle. 

No CEL. Scanned and returned a active P0455. 

Ran Active Test to see if customer left gas cap off in the past, code remained. Replaced Gas Cap and retested. Code Remains. 

Ran Smoke test on vapor line “tank to manifold”. No smoke (I believe there's a check valve in the way I've yet to confirm).

Ran smoke test on Purge Valve Control Solenoid: Pumped smoke from Manifold-to-PVCS vapor line, then commanded PVCS to open/close which functioned correctly; heard the click and then the hiss of flowing smoke, the the click and close; No leak/visible smoke.

There's no Bi-Directional control through my scanner for the Canister Vent Valve, and I can't command a total seal like on GM stuff, but I think there's a check valve in the vapor line fighting me anyway.

Evaporative Emissions is an area of auto-tech I don't see often due to the general age of cars I work on and generally the failures I deal with, so I'm weak on it and need a little guidance.

I suspect there's a failure either in the fuel tank seal for the pump or back by the charcoal canister, but I don't know where to start and how to avoid false positives with diagnosing all the vacuum/vapor/return lines by the charcoal canister.

I've included some pictures. Can anyone put me on the right path to diagnose this correctly?

Thank you all!

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Rod Diagnostician
California
Rod
 

Do you have the freeze frame data?

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Rod Diagnostician
California
Rod
 

How intermittent?

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Jordan Owner/Technician
Washington
Jordan
 

I have not been able to reproduce the customer complaint as yet; I'm exploring every possibility such as fuel delivery, stable ignition circuit etc. Starting and Charging appears fine, but the ALT belt is a bit loose and I will be replacing that and spec'ing the tightness. Also considered that if the belt was loose and got wet, might slip and cause customer complaint.

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Obie Technician
Washington
Obie
 

To properly test the purge solenoid valve you need a vacuum gauge that reads inches of WATER. Connect it to the purge line, disconnect solenoid connector and start the engine. If there is any vacuum on the gauge the solenoid is bad. Repeat the test after activating the solenoid with the purge hoses connected. I do not believe a large leak causes any loss of power. A gulp of fuel vapor thru the…

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Helpful
Jordan Owner/Technician
Washington
Jordan
 

Thanks Obie, I will test this. I haven't been able to recreate the customer complaint, but I'm pursuing all areas of possibility. I was wondering if exactly as you suggested could be the case.

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Matt Technician
Texas
Matt
 

Hey Jordan! If "Fuel Tank Pressure" is an available PID on your scan tool, I'd start pinching stuff off and watch the Fuel Tank Pressure on a graph for “bleed off”... whether it's voltage, or an actual pressure measurement. It looks like you've already isolated a few things out of the picture. Keep loo… and don't give up!

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Chester Instructor
California
Chester
 

The purge solenoid is your likely culprit. Does the vehicle act flooded after a fill-u?

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Jordan Owner/Technician
Washington
Jordan
 

Customer did not supply that information. Just that it does it during driving. Customer has limited mechanical repair understanding so I will just fill it up myself and test this.

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Tony Owner/Technician
Missouri
Tony
 

“This ”power loss" complaint, is it described as noticeable while under significant load, or only light load/cruise/idle?

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John Instructor
Pennsylvania
John
 

If you know how to test a GM system, then you can test this system as it is almost identical. You may not have bi-directional controls, but you can use jumper wires to command the cannister close solenoid to seal the system and the purge valve to supply vacuum. Then you can monitor the fuel tank pressure level to see how strong of a vacuum is pulled. A lot of manufacturers use around 8" of water…

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Tad Owner/Technician
Florida
Tad
 

Jordan, My first question is: Why is there “no CEL”???… Large leak should have that light on continuously. Does the CEL even function? Has your customer been riding around with it on for so long that it burned out the bulb?… If that's the case, your large leak code, likely, has nothing to do with the symptom/complaint and you're chasing something that your customer doesn't give a tinkerer's damn…

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Jordan Owner/Technician
Washington
Jordan
 

I found this odd as well with a Current P0455 and no CEL. The CEL works; it's on right now with Key On Engine Off as I type this. Rescanning after coming back to the shop over the weekend and the P0455 has disappeared out of the PCM after multiple hours of testing. The battery did not die over the weekend, however. I was never able to get smoke to come out of the old gas cap as I believe…

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Tony Owner/Technician
Missouri
Tony
 

If John Gillespie's statement about these evap systems being almost identical to GM extends to the check ball in the bottom of the filler neck (a GM staple), then you won't get smoke/pressure to leak past a bad gas cap because it is being stopped at the bottom of the neck, close to the fuel level line, before it can reach the cap. You can easily pressure test the cap separately if you get the…

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Jordan Owner/Technician
Washington
Jordan Resolution
 

After replacing gas cap and multiple re-tests using my scanner as well as road tests, P0455 has not returned. Unfortunately I don't yet have a robust set of EVAP emissions tools, so cannot 100% confirm single failure point of EVAP system for this vehicle. Since the code stayed away and customer inquired when the vehicle would be ready, I released it to them. Thank you all for your knowledge and…

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