DIY LS430 VSV (VACUUM SWITCHING VALVE) for EVAP cleaning / replacement procedure
 

This DIY guide will help you make a decision / determine the right steps to do the proper maintenance of one of the most important elements of Lexus LS430 exhaust / evaporative system - VSV (Vacuum Switching Valve) - which may have other names as well, including EVAP Purge Control Valve, or EGR Valve.

This DIY Guide applies to you if:
- LS430 is above 100k miles
- LS430 2001-2006 years of production
- Maintenance was never done to evaporative system
- The intelligent scanner / techstream / regular DTC code reader does or does NOT show any DTC codes related to evaporative emission control system
- There is a need to do the maintenance of VSV valve.

The goal of DIY was to:
- Test the theory that the valve plays the key role in ensuring the exhaust gases return to throttle body precisely according to ECM instructions
- Test the theory that the valve may directly or indirectly involved with a much broader processes going on in the engine / transmission that previously thought / miscommunicated.
- Verify what is the practical result of cleaning the valve in terms of safety and emissions control (by seeing if any DTCs appear afterwards)
- Determine if any practical benefits results from this procedure.

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Lexus / Toyota created Owner's Manual, Service Manual and Dealer Workshop manuals to help service LS430 and offered substantial amount of information available to understand the subject of this part of emissions system. At the same time, Lexus / Toyota did not decide to elaborate on the following procedure, not to mention that dealers do not even look at this part unless they do electronic diagnostic and uncover the DTC code.

So let's look at the guide and Lexus visual materials to make our own conclusion whether it makes sense to clean / replace VSV (EGR, PURGE VALVE) or not.

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1) What is Evaporative Emission control?

According to Toyota, "The engine ECU controls the purge flow of evaporative emissions (HC) in the charcoal canister in accordance with engine conditions." Lexus is capable to detect evaporative system leaks / low inputs / high inputs and inform the driver through Check engine and DTCs.

2) Is there a difference between VSV (Vacuum Switching Valve) and VSV (For EVAP)?

Yes. LS430 has two different VSV systems. One is located within ACIS (Acoustic Control Induction System) (between the engine and cabin), while the other VSV is located on the driver side of the engine (visually observable).

VSV (Vacuum Switching Valve) in ACIS system controls the vacuum that is applied to the actuator by way of the signal (ACIS) that is output by the engine ECU. The intake air control valve, which is provided in the middle of the intake manifold in the intake air chamber, opens and closes to change the effective length of the intake manifold in two stages..

https://cimg8.ibsrv.net/gimg/www.clu...59c3004cbc.png
VSV (for EVAP) regulates evaporative emissions (EVAP) from the fuel tank that are routed through the canister to the intake manifold for combustion in the cylinders. After the engine is warmed up, the ECM changes the duty signal to the EVAP VSV so that the intake quantity of EVAP is appropriate for the driving conditions (engine load, engine RPM, vehicle speed, etc.).

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3) What does Toyota / Lexus recommend about inspecting the VSV for EVAP?

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4) Is cleaning the VSV (for EVAP) a maintenance procedure recommended by Toyota / Lexus?

No, due to unknown reasons.

5) What would happen if VSV (for EVAP) valve becomes clogged or malfunctions or stucks open?

As was mentioned earlier, when the engine is running under certain conditions, the fuel vapors are purged from the charcoal canister and burned inside the engine. This valve precisely controls the amount of fuel vapor that is purged from the charcoal canister.

This valve is electronically controlled solenoid which is designed to gradually open to allow some amount of fuel vapors to escape the canister and enter engine through throttle body.

Lexus / Toyota engines are supposed to inform if the valve is malfunctioning or somehow obstructs the normal emission control system. However, without proper testing, there is a reason to believe that the ECM still cannot perfectly determine whether VSV (for EVAP) is clogged or has dirt inside of it. If the VSV valve completely breaks and stop working, than the ECM will illuminate check engine light. However, it may be too late as some damage may have been done to evaporative and other systems.

Google offers this possible scenarios when VSV valves goes bad:
- Impacted Air to fuel ratio
- Rough idling (car feels rough and bouncy when the engine is running)
- Difficulty Starting
- Engine will feel weak
- Engine stalling
- Engine misfires

6) Is it ok to remove or block VSV completely to avoid problems?

No

7) Do dealers talk to clients about this problem?

To my best knowledge, dealers do not look at this part unless they see DTC. And this is where the problem is - the ECM doesnt detect if the valve works poorly (outside factory specifications) unless it is completely malfunctioned. Therefore, nobody is aware whats going on in the valve unless the client has multiple evaporative emission codes. As it is well known, by that time, the damage is already done to the engine which causes expensive repairs.

8) What can you do to avoid the problem with evaporative canister / vapors?

Not only that everyone who owns LS430 may do the following inexpensive maintenance procedure, but also receive SUBSTANTIAL benefit for their car (i will explain later) as confirmed in my case.

Basically, the $5 fix include removing VSV (for EVAP) from the engine (2-3 minutes), deattaching two rubber hoses (30 sec.), applying the good spray of WD-40 in both channels until everything gets cleaned out and lubricated. Make sure you give 20 min at least to ensure the solvent is evaporated from the valve.

Install everything back. You are done with this procedure.

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9) What did I notice immediately after this procedure?

And this was the whole reason why I decided to create this DIY guide. I am amazed about what role does the valve play in LS430. Once it returns to its normal factory status, the results are unbelievable. Here are some of the beneficial effects that I am currently observing in my car:

- Engine vibration has been significantly reduced from low to super low.
- The Idle RPM has been stabilized and no longer "float" as much as before (we are talking about minimal discrepancy, but still makes a difference).
- Engine runs smoother (definitely confirmed by multiple people)
- Acceleration.... Until the day i did this DIY i thought my acceleration was smooth. Well now it is even better. I also noticed my RPM stays STABLE during acceleration.
- No longer I feel the smell of fuel when exiting the car. I always thought it was due to my new exhaust setup.
- AND THE BEST FOR THE LAST - MY FUEL CONSUMPTION DROPPED by APPROXIMATELY 35%.This conclusion is not subjective, my average MPG in the city is STILL (!) going up 0.1 mpg every 20 min of driving. Its been a week since i did the cleaning, and I am absolutely surprised that my 3UZ-FE is still adjusting to new "setup" and keeps pushing economy up.

Overall, I recommend to all forum members to consider this DIY with your quest for better engine work, quiteness, lexus comfort, saving money, and taking care of the future of our cars.

Also, there is a theory that dirty VSV for EVAP affects AISIN transmissions as they collect information about its operation and resulting torque. Due to the fact that my transmission is already super smooth after SIA fix, I am looking forward to hear from other forum members whether they observe an improvement in shifting quality after performing this DIY.

Opened for feedback.

ls430w140.......Very nice comprehensive write up. I have gotten the P0440 code (evaporative emission control system) on a regular basis for the last year or two. After clearing it, it reappears in about 30 days of driving or so. Car accelerates and idles well. Trans shifts smoothly. Only symptom is gas smell after driving and shutting car off in my garage. The smell is outside the car, never inside. Driving 99% city I average 14 mpg. Highway I'll get in mid 20s. My Indie has performed the smoke test and I have replaced almost every vacuum line I have access too with OEM parts. After speaking with the Lexus shop Foreman, he believes it is most likely the charcoal canister and or purge valve. Lexus has not looked at my car. I have none of the symptoms you mentioned above, but I do have the gas smell after shutting off car and of course the CEL. I'm not mechanically savvy, so I'm not able to perform the above procedure. I can run it by my Indy who was a service manager for Lexus. .

Thanks for great questions.

I used WD-40 as I needed it’s power to clean up and lubricate the interior of the valve. I assumed that 117k miles could ve brought serious build up, therefore more evaporative solutions like MAF sensor cleaner could not have done the job. Do you know if another product is more suitable?

Mileage improvement is definitely taking place, in both average and current numbers. I will post final statistics once the testing period is over.

i couldn’t find specific operational parameters of Denso evap valve, however, to my best understanding, it works in pulse width modulation which may, as you say, consistently close and open valve to reach certain targeted parameters of incoming air amount

Thanks for reading my guide.

Did anyone test purge valve? I highly recommend you to go ahead and clean. The procedure is extremely simple. Once the valve is cleaned, you can make determination if you need to look further at the canister (which is a big job)

My car has some of those symptoms I’ll give it a shot in the next few hours I’ll update thank you great post

Sure, why not. Especially it has no burden on budget to get it cleaned with a solvent. Look at it as ensuring the valve is properly supplying circulated air back to your system ensuring that your engine is greener and more efficient.

What is your average mpg? And how many miles do you currently have?

Correction 1. LS430 doesn’t have EGR (exhaust gas recirculation) system. It seems that either VVTI or other onboard system takes care of this. VSV only handles fuel tank pressure / evaporation. Which even more interesting for me now to understand why does it have such an effect?

Any other experiences will be appreciated.

I was curious as well...
I found these 2 not sure which it is though.

https://www.lexussouthatlantaparts.c...586050121.html

https://www.lexussouthatlantaparts.c...586050100.html

I tried it out my 2 rubber hoses were pretty dried up so I took it slow as soon as I squeezed the tab for the connector it broke sigh, I blew air threw one end and nothing came out the other end so I wasn’t to sure how I was suppose to fully clean it with wd40, op how did you clean yours did you just clean the tubes or did you open the valve ?
208k miles
14 mpg in the city
27mpg on freeway 70mph and up

The second link. Part# 25860-50100
ebay has them about $15 cheaper

Took mine off today, clean as a whistle, but im still under 80k miles. Rubber hoses are getting nice and stiff however ��

My suggestion to anyone considering to clean the VSV valve.....be prepared to possibly having to replace some or all of the vacuum hoses in that area as they will most probably be hard and brittle from engine heat and age. I replaced most of them a few years ago with all OEM hoses from Lexus. Cost was about $35. Yes you can improvise with a cheaper universal hose but I wanted it to look neat and it wasn’t all that costly.

interesting DIY and will give it a try this summer :)

By chance would you have part #'s associated with the hoses you replaced from Lexus? I, too am interested in replacing with OEM hoses...