Bly

Well, after almost one thousand miles I think I've solved the problem. When I changed the plugs I found that one plug, the second one in on the drivers side which I think is no. 4 was loose. I replaced all the plugs although the old ones didn't seem that bad but while I had it apart why not? Anyway, it hasn't stumbled in almost 1000 miles so I think the loose plug was the problem. I have no idea why the plug was loose. They were the original factory plugs and had never been changed. The new plug seated on the washer normally. Very strange.

Was it a real Lexus update disc or a copy someone burned? I've been told that non original nav DVD's don't work well in older generation Lexus's Nav systems. They might work in a later year but not in a 2002. Assuming that's what you tried you might have to break down and buy a real one from Lexus.

Brought the car in today to my local guy who used to work for Lexus. He plugged in the scanner. No codes at all. We rode around for awhile with the scanner plugged in. Nada! $114.00 later, nada. I'm going to change the plugs and clean up the coil pack boots and see what happens. Maybe a plug or a boot will give me an ah ha moment. I doubt it but I don't know what else to do. I may just have to live with it until it really lets go but I've been doing that for about three or so years! BTW, it hasn't done it again in about forty stop and go miles. Really nuts.

Thanks for the heads up on my profile. I don't think it's the plugs either but they have about a 100,000 miles on them so it can't hurt to change them. I intend to keep the car for a long time. I'm thinking that maybe one of them has a crack or a carbon track on it that once in a while shorts out and causes the stumble. There are no codes. I'd bring it into Lexus or my local guy who used to work for Lexus but the problem is so intermittent that I don't think they'd be able to find it anyway. My feeling at this point is that if I do bring it in eventually I can say, I changed the fuel filter and pickup screen, I changed the plugs, I rotated out all the coil packs and I still have this issue so you don't have to do any of that and can look elsewhere (to things that I don't have the ability to test or change). I'll keep all of you up to date on my progress and hopefully an eventual solution.

I've given step by step directions on changing the fuel filter on a 2002 SC430 on the topic, "anyone change a fuel filter"

Well, after 47 miles of stop and go without a cough I had two in a row upon starting from a dead stop so I guess the fuel filter was not the fix. Still, not sorry I changed it as it had some crap on it. Next I think I'll change the spark plugs and if that doesn't do it I'll buy one coil pack and switch them out until hopefully I find the problem. Anyone have any other ideas as to what would cause a very intermittent engine miss. It's almost like a momentary stall although the engine has never actually stalled. If anyone is experienced with marine engines, it's like the ignition interrupt stall when shifting a Mercruiser IO. The same kind of feeling. Any suggestions would be appreciated.

OK, here's how to replace the fuel filter on a 2002 SC430. I'm sure later years are the same. Obviously first order the parts. You'll need the filter, the pick up tube screen and you should probably get some clips if you're changing the pick up screen because you'll mangle the old one getting it off. Order a couple because they're cheap and I destroyed the old one getting it off and one new one putting it on. I bought two. If you're not changing the screen you don't need the clips. I'm told that the screen can be cleaned with brake cleaner but I replaced it while I had it all apart. Anyway, first, put the top down so you have room to work and then move the front seats all the way forward. Then I suggest that you disconnect the battery just in case of a spark and of course, no smoking or open flame. Take out the back seat by reaching under it on both sides and lift up. It will pop out fairly easily. On the drivers side you'll see a triangle plate with three plastic nuts and a wire running through it. Take off the nuts and lift. You can slide out the rubber grommet from where the wire runs to give you some play but the wires stay attached. Under the plate you'll see another plate with eight phillips head screws. They don't look like they had an edge for a socket but they do and I needed to put a socket on each of them to break them loose. Then unscrew with phillips head driver. The plate lifts off. Then there is a little plastic locking clip surrounding the fuel line connector. Slide the clip off (mine was yellow) and lift off the fuel line. You'll get some leakage here so this job is best done outdoors. At that point you can lift out the entire assembly. You have to reach in a bit to release the hose that comes from the opposite side of the fuel tank. Slide the clamp down and pull that hose off. Now you have two loose hoses, The main fuel line and the one that runs to the other side of the saddle fuel tank. Carefully lift out the whole thing without bending the sending unit wire. Once out you need to take it apart using two flat head screw drivers on the several plastic clips that hold the whole thing together. Once apart replace part for part from the old filter to the new. The entire fuel pump fits up inside the filter assembly. Once you get the wire connector off the fuel pump itself you can take the part out of the back seat area and have room to work. Assembly is the reverse. The only problem I had was that when it was all done and back together and the car running I noticed that the gas gauge was about a quarter of a tank too high. I had run the tank almost empty before the job. I took it apart again and noticed that the sending unit wire had come off the plastic clip near where the calibration adjustment was. I clipped that back together and reinstalled but the gauge was still wrong. I thought that maybe it takes the computer some time to average fuel level and went to fill the tank. After driving about a mile the gauge came back to where it was before I started the job. I don't know if this will fix my problem. Time will tell but I did see something that I think is strange. While I had it apart I opened up the secondary side of the fuel tank. Just a sending unit there. That side of the gas tank was dry!!!! The main side had several inches of gas in it even though the light on my gas gauge was on. So I'm thinking that maybe my problem was that the pickup on the main side was partially clogged and I was sucking air on occasion from the secondary side into the fuel line and that's what was causing my intermittent skip. Again, time will tell.

That's perfect! Thanks so much. Who would have thought it was called " a piece"? Go know. Thanks again.

Anyone know what the small square piece in the rear bumper that covers the tow bar/strap down bar recepticle is called? Maybe a part number? There is one on each side of the rear bumper. One of mine fell out and I don't know what the piece is called and have been unable to find a blow up parts diagram on the web. The piece is about a 2.5 inch square.

No, that appears to be a different process with the filter under the car. The 2002 SC430 has the filter inside the gas tank and is accessible through a hatch under the rear seat. Thanks anyway. Probably releasing the pressure by removing the gas cap is not a bad idea though. I don't know if it's necessary but it coulldn't hurt.

I've learned that the fuel filter is a part of the fuel pump assembly which is located in the gas tank. There is an access hatch under the rear seat. The filter is available either from Lexus on line or as an after market for between $20 and $30 bucks or so. The genuine Lexus part being slightly more expensive. There is also a screen on the pick up tube in the tank. Actually there are two pick up tubes but they both connect to the pump. Also two sending units. One on each side of what is called a saddle tank. I probably won't get to it for a week or two but if I do it I'll get back on to advise of the difficulty.

Of course, you're right. It's a 2002 SC430. I hope it's not in the gas tank although I have a feeling that it is. Anybody have any experience doing this on a 2002 SC430?

I have a similar problem although I don't think it's as severe as yours. I think it's a fuel delivery problem in our high mileage cars. Junk in the fuel tank that get sucked up into the engine or blocks the fuel filter. I had been told that Toyotas have a "lifetime fuel filter" (sort of makes me wonder what they do?) but I see on line that the SC430 definitely has a replaceable fuel filter. I posted a topic today to see if anyone had changed the fuel filter on an SC430 but no replies yet. For all I know it's in the gas tank and that will be a major job to replace. If you've had any luck getting rid of your problem please post what you did.

I think I have a clogged fuel filter as I have a very intermittent cough that seems to improve for a while when I treat the fuel with cleaner. It happens so rarely that it's been tough to isolate. I thought that there was no fuel filter on this car but I see that the part is available for about thirty bucks but I don't know where it is or how to change it. For all I know it's in the gas tank. Has anyone changed the fuel filter and if so, how? Thanks

There are four bolt up high in the wheel wells on both sides. I had the same problem and my mechanic put an impact drill and a torque extension on them (from underneath). Tightened them up and noise was gone. It seems they have to be very tight. Of course also make sure the rest of the front end is right.