Hello all, I decided to start a new thread as I can't find anything covering my question. I am a long time SC400 owner and member, but recently got my hands on a 2004 SC430 that was in need of attention (and lots of parts). It sat outside for a year at the repair shop before I started working on it, so nothing surprises me about the problems I have found. But, to date, I have gotten everything sorted out with the exception of lingering EVAP codes. I have replaced or checked everything under the hood related to vacuum, air, and VSV's, and still have the codes. I am an engineer, so started by educating myself about what the system does and how it operates. There is a whole series of excellent tutorials on You Tube, but I must warn you they are long and detailed. So now, I am starting to convince myself that the issue is the self test function of the EVAP system, based on the codes I have (P0441, P0446, P0455, and P2418) and how they get set. I am pretty sure the motor that is used by the EVAP self test is not working, therefore it fails the test and sets the codes. But to evaluate, I must remove the charcoal canister. I have tried numerous times to get access to the various hoses and parts on the canister, but can't seem to get to them adequately. The canister is mounted directly above the differenctial to the sheet metal that makes the floor of the trunk. I have a lift in my garage and have really examined this closely, but it looks like the only way to get adequate access to remove the canister is to drop the rear subframe. It's certainly doable (did it on my SC400 one time and a BMW as well), but it is a lot of work with old rusty bolts and a significant PITA. I have researched endlessly and can"t find anything regarding recommendations for getting the canister in the SC430. Other Lexus models I have found, but the canister mounting and location seems to be unique to the SC430.

Does anyone on this forum have any first hand experience with removing the canister or know where or if there is somewhere to find this info? I have the service manuals, but nothing in them covering the canister. I do not have access to the Lexus hand held tester to use for diagnosis in place, therefore need to remove it to gain access to the connectors and fittings to perform the diagnosis. Any suggestions are appreciated short of ignoring the problem. As I said, I'm an engineer and i can't seem to ignore thsse kind of problems, I have to fix them. I am likely going to put in a new canister, but I still have the smme problem of needing to get the old one out.

Thanks in advance for the help and sorry for the long post.

 

When I first got my SC I had a similar problem. I was sure it was the charcoal canister. I posted my problem here and the folks convinced me to check the vacuum hoses under the hood.

Sure enough, one of them was cracked. I replaced it and another one cracked the same day (Due to the increased pressure). Then another one cracked.

I ended up replacing them all and my problem went away.

It COULD be your canister, but charcoal canister failures on a sc430 are RARE. Usually only if there is an accident involved.

However, cracked vacuum hoses under the hood are VERY VERY VERY Common and they give the same codes as a pump that is unable to draw a vacuum

 

Or, repeated overfilling/topping off at the pump can kill a charcoal canister.

 

Thanks for the responses, it is appreciated. I do have concerns about the history of the car and have no idea if the previous owner made a practice of overfilling/topping off the tank. Given the general condition of the car when I got it does concern me. As far as the underhood components, I have replaced all underhood vacuum and air hoses with new OEM hoses ordered from Bell Lexus, including the service port. I also checked all the hard lines for obstuctions. I found one defective underhood VSV during my diagnostics. Some of the vacuum hoses were noticably defective. Initially, I was getting additional EVAP codes, but some of them were corrected with the new components installed. However, the four remaining codes have been solid since then. I should also add the P0441 get thrown for all EVAP code failures. But having both the gross leak and small leak codes thrown at the same time most likely leads to the pump motor not working or the bypass VSV being defective.
I should have been a little clearer about the reference to the charcoal cannister. I am referencing it as an assembly, as it contains has additional switching valves (EVAP VSV, EVAP Cannister Vent Valve CCV, and Bypass VSV) and the motorized pump mounted as part of the assembly. Testing those components are not possible without the hand held tester or removing the cannister for bench testing. Even the hand held tester is not 100% conclusive about which component might be defective. But, nevertheless, if one is defective, I am still faced with removing it for repair. I have also determined that those components are not available separately.
The SC430 cannister assembly is identical to the GS 300/400/430 cannister assemble, but it is in a more accessible location on that car. I watched some You Tube videos for that car, and in one of them the poster dicsovered the pump motor to be gummed up and inoperable as a result. He was able to clean it and get it to work again, but not before he already installed a new cannister assembly. However, other comments to the video indicate a number of people tried to tap the motor in place, which resulted in the test working afterwards. I have tried that as well, but couldn't get the same results. I am going to try again, but its tricky getting something up there to tap on it. And I have to know it's being commanded on to ensure there is voltage being applied. It turns on at the beginning of the test, and knowing exactly when that happens is kind of pot luck as it's dependent on factors such as fuel level, intake air temp, etc. The pump motor is not specifially depicted in the electrical diagram, but I think I have located the ECU output terminal that turns it on. I think the motor is included in the component identified as the Fuel Tank Pressure (FTP) Sensor. However, I keep coming back to if it's bad, I will still need to get the cannister assembly out somehow.
I really do not relish the idea of removing the cannister assembly, but so far, can't figure out any other way to figure out what's wrong. I also don't like throwing parts at a problem without some evidence of a failure, but in at this point I believe I have replaced everything that I can reasonably access.

 

Can you get access to a copy of techstream? I think you could test it further for a nominal investment. Would you be willing to make your own smoke machine to test for other vacuum leaks?

Otherwise, I think I looked at dropping the gas tank to get to the canister.

 

I wanted to follow up with everyone for future reference for EVAP issues with this car. I finally decided I needed to pull the Charcoal cannister to evaluate the issue adequately. But before that, I determined that I made some errors in diagnosis by not paying attention to some of the details during my investigation. Primarily, I found that the SC430 does not use a motorized pump to perform the EVAP testing. The information was for a different Lexus model and came up on my SC430 search, but wasn't readily identified in the title. So went back to the drawing board, but still came back with the conclusion that the bypass VSV was the likely problem (because code 2418), and it's mounted to the Charcoal Cannister. But before removing the cannister, I did find two more hoses connected to the canniser that were cracked in similar fashion to those under the hood. I replaced both ot them and performed more testing, but still had three of the four codes, including P2418. Next step was to remove the cannister. I did find information from a GS430 post where someone removed the right drive axle and was able to fish the cannister out. After having a good look under the car, decided that was the way to go. So here are the steps I took to remove the cannister:

1. Set the parking brake and remove right side wheel/tire.
2. Remove the two body mounting set plates and both rear suspension member braces, front floor brace, and both rear lower suspension member braces. Watch out for rusty hardware so you should spray down in advance with some sort of penetrating lube.
3. Loosen the 6ea 10mm hex cap bolts that hold the right side drive shaft to the differential. You can remove the bolts later, it's just easier to loosen them now. You will need various ratchet extensions and wrenches to access all the bolts unless you release the brake and take the transmission out of park to turn the right rear hub.
4. Remove the camber adjusting bolt holding the No. 2 lower suspension arm to the right hub carrier (mark the position first).
5. Remove the bolt holding the No.1 lower suspension arm to the chassis.
6. Disconnect the exhaust at the rear Cat junction. More rust here to be wary of.
7. Remove the two rubber supports for the exhaust. No need to remove the donuts at the rear of the exhaust. Let the exhaust pivot down at the CAT junction,
8. Remove the 6 cap bolts holding the right drive axle to the differential and push the axle towards the outside of wheel well until it is free. It might take some work with a hammer to get it loose. Once it drops down, push it towards the front of the car between the exhaust and the bottom of the car body.
9. Remove two nuts holding the evap baffle to the body and remove the baffle. It's a plastic triangular shaped part with holes in it with the large vent hose from the cannister. Getting this out gives you more room to work the cannister out.
10. Remove all the connectors and hoses from the cannister, and the three nuts holding it to the body and maneuver it out on the right side through the opening created by moviing the drive axle.

Reasssembly is in the reverse order. Hope I didn't forget something, but don't hesitate to ask if something doesn't make sense. In the end, I'm not so sure the sequence is all that important, but that's how I did it. And one more thing I almost forgot. Don't final tighten the bolts on the two suspension arms until the car is back on all four tires.

Lucky for me I was able to do this from my four post lift. Doing this on your back on the ground may be a lot more difficult. But I think it's still doable if you are young and flexible, and you don't have to drop the entire axle carrier. I'm old, slow, and methodical, so it took me one afternoon to get cannister out, and another morning to get the new cannister installed and everything put back together. About 8 hours total.

So what did I find? Well, the bypass VSV was definitiely bad, and one of the hoses I couldn't reach was also bad. I have no idea the condition of the FTP sensor, but since I decided to purchase a new cannister assembly, I didn't have to worry about how to test it. I could have looked around and found some other VSV that would have likely worked in the place of the one mounted on the cannister, but since I found so much already bad in this car's EVAP system and don't know the car's history, spending another $450 didn't seem like a bad way to go. Once I got the new cannister, I got it installed and retested the entire system. All is working as designed with no more codes.

Hopefully this will help someone in the future. As these cars get older, this will most likely be something that folks will be looking for.