curiousB

I'd start by seeing if one of the coils and/or associated wiring is bad. These cars are famous for problems with ignition coils so its a high probability place to start. The fact it runs rough sounds like you might be running on 4 cylinders and dumping a lot of unburnt fuel into a heated exhaust stream. The CATs are probably red hot after a drive... Take a look at them after driving at night. If they are glowing red this supports bad ignition theory. Could be O2 sensors too but that wouldn't explain dramatically bad running engine. It would explain poor gas mileage and some loss of power but even in open loop mode engine should run reasonably. Also its not likely you'd get more than a single O2 sensor failure at a given time. The two secondary O2 sensors exist to see if the CAT is performing so they wont effect performance. The two O2 primaries are used to trim fuel mixture but as I said even if one is not working the car should run somewhat OK.

did you rule out ignition?

yes. If you have a bad coil it generally means the car is just running on 4 cylinders. That being the case if you unplug the bad coil you won't notice any performance drop with the engine (since it wasn't working anyway). Now reconnect and try the other bank. If it is good disconnecting it should kill the engine as with the other 4 cylinders already dead you'll now be now down to zero.

Since it is such an expensive part I would try to diagnose it a bit further before throwing parts at the problem. As for poor idling here are some suggestions to check: Check for leaks (cracks, loose fittings) in all of the air ducts between the intake manifold and MAF. Do a throttle body cleaning if one hasn't been done in >25k miles. Check that the IACV is not gummed up and is freely moving. For the 25MPH symptom I would be sure you don't have an ignition issue. These car are notorious for coil problems that kill one bank of cylinders and dump a lot of unburnt fuel into the exhaust system (red hot catalytic converters). Many threads on this website to diagnose that issue.

Why have you concluded you need a new MAF? Do you have ECU codes? Other symptoms?

The trick to tightening is holding the crank from turning. I bought a tool for this http://www.denlorstools.com/home/dt1/page_11038/schley_64300_toyota__lexus_crank_pulley_holder.html Other than that a bar and some elbow grease. My torque wrench didn't go that high so I went to 150ftpd with it then used a 30" breaker bar to torque it a little further. I have heard of people jamming the flywheel with a large allen key to stop crank from turning instead of a holding tool.

The marks on the pulleys (not the belt) will sync up every second crankshaft revolution.

I've had a slow leaking tire for a couple months. Its driving me nuts. Every 5-6 days the tire warning indicator comes on and sure enough the same tire is down to around 20psi. I took it back to tire place and they removed and remounted tire after they claimed to see a bead leak in the dunk tank. They used some gunk on the bead to seal it and it worked fine for almost 2 weeks. Today warning came back on. Last time there the tech said there was some corrosion on the wheel where the bead meets. Have others heard of aluminum wheels corroding such that a good seal is no longer possible? Also how does salty water get into the bead when the tire is 20-32 psi this any leak would be expelling air, not leaking in salty water. It all seems strange to me.

I think there is a lockout feature for low refrigerant to protect the compressor. You might still have a leak and the system is protecting you from making matters worse. This is pretty specialized knowledge (AC/Refrigeration). I would be inclined to work with dealer on this issue as they know the common problems with the various models. Not really DIY.

I don't have time to read the novel here but poor idling is typically a vacuum leak, dirty throttle body, and/or dirty/sticky IACV. I'd run those to ground befoe chasing a compression conspiracy theory. Its usually the simple things, not the complex ones with these cars. The fact you can fix it by pressing pedal some suggests its just not getting enough metered air.

Is there a question here?

I got to disagree with you on this one Billy. I think the service guy should recommend what needs to be fixed and other issues should be addressed "while in there". Hard to see how regular owners would know what to ask for. I wonder if the service writer is concerned about $$$ sticker shock of the extra work, or are they happy to do it over later when the seals fail. Maybe they just don't see many seal failures and feel its not worth the extra $$... I did my own TB 23 months ago and didn't do seals. If I have the car at 180k then I probably will do then seals on next TB cycle.

If it is oil it is either coming from the seals on the cam shafts or the main crank. A lot of people recommend changing these while doing a TB job as most of the effort is done to get at the TB. Once you are there it isn’t too much extra work to change the seals. I wouldn’t bother trying to save the TB. The cost of a new belt is nothing compared to the labor to fix this oil leak. Salvaging the TB is the least of your worries at this point. As for hammering your service guy. I guess it depends if there were signs of a leak back then. He is likely to deny anything and you'll be hard pressed to prove otherwise. Maybe you can negotiate a settlement where you only pay parts and 1/2 the labor to fix the leak as compensation for failing to recommend new seals back then... You decide how to proceed but my feeling is a full on flamethrower assault probably won’t help. The facts aren't strong for you. I think I’d appeal to the guys sense of fairness instead.

easy, 1/2 hour should do it. You might want to get an O2 sensor socket to make it a little easier ($5). http://www.harborfreight.com/3-8-eighth-inch-offset-oxygen-sensor-wrench-97177.html

Double check the timing. Manually rotate the crankshaft to TDC. Remove belt top cover and see if cam pulleys align to marks on back cover. If not rotate crank one full turn and check again. These have to align exactly or it won't work properly. Close enough doesn't cut it here.

Rebuilt? Electronics?!!! Its not like a cylider head that needs valve grinding. What are you trying to resolve by "rebuilding" it? Do you have symptoms?

It may not be much of a crack so don't expect to find a large one. Once the shield are off you can listen for it with a 2-3' length of flexible tubing. Hold one end near your ear (don't stick it in your ear!) and move the other around the suspected leak. Once you pass tube over the leak you will hear it!

don't forget two new o-rings for the water supply tubes. They don't come with Water Pump kit. It seems they should.

This is a pretty long thread with many twists and turns. It is pretty clear there is a problem with one or two exhaust valves on cylinder #1 and that it is likely to do with propane fuel which is more common in the UK. The car is in good shape but with many miles it makes for tough choices on economic viability of various repairs. A new engine is out of the question and a rebuild of the head is likely borderline on a cost-benefit basis. Maybe a salvage yard head swap might be ok but its a big undertaking. At this stage the OP is hoping to find uniform valve seat wear such that readjusting the valve shim can result in a better closure of the valve. Its a long shot but given the cost of other options its probably worth a look see.

I had a 1980 Honda Accord (FWD) up in Canada back then. I had a pair of radial snow tires mouted on the front wheels every fall and switched back each spring. That car was fabulous in the snow. All the weight is on the drive axle instead of the lighter rear end. The car pulls you through the snow rather than tries to push you. I survived a substantial blizzard one winter where I could could power through the snow drifts yet all the rear wheel cars were stuck in their tracks. I don't know where this anti front wheel drive sentiment comes from but I have lived it in severe weather and I am positive it is an unfair judgement. I'll take FWD and snow tires anytime in snow and ice. Now with ABS and Stab control it is even better.

Isn't it easier to determine an exhaust valve leak by your leakdown test anyway? A visible indication isn't as telling. This chart shows where both sets of valves should be fully closed a leak test at the sparkplug would tell if they are leaking. If the exhaust is the culprit it will leak to the exhaust pipe and you should hear it there, Intake would be at intake manifold, rings would be via the dip stick. I'm not sure what you gain by checking valve clearance other than what you know today. I believe you've confirmed the valve leaks. It was your intuition from the start. You are running on 7.5 cylinders. I'm a little surprised you don't have an emissions code popping in the car. If the valve is that gone I would suspect unspent fuel is leaking by the valve and burning in the exhaust manifold/ catalytic converter. Might be interesting to look at the LT and ST fuel trims in the ECU to see if it correlates to this at all.

Isn't the normal wear for values to be they open less as wear sets in? The push points establish the travel and if they wear the valve travels less. So failure to seat wouldn't be wear but damaged valve seat stopping a tight closure. Instead of a valve job why not buy a used head from a wrecker and install it. That might be a lot cheaper than a trip to the machine shop and new valves and regrinding. If the other bank is still factory original it doesn't make a lot of sense to me to have one bank perfectly new while the other is 200k+ miles on it.

I removed the heat shields to weld up the holes and never put them back on. Perhaps not ideal but I didn't feel like spending $1,200 for a new Y pipe just so I could put shields back on. Once an after market Y pipe is available for my year (2004) then maybe I'll swap it out. I believe you can buy one on ebay for <$300.00. Might be a cleaner solution. Also I think this is Stainless steel so should last longer than the plain steel OEM pipe... http://www.ebay.com/itm/2001-2002-2003-LEXUS-LS430-CATALYTIC-CONVERTER-51868-/250752773519?pt=Motors_Car_Truck_Parts_Accessories&fits=Make%3ALexus|Model%3ALS430&hash=item3a6207ad8f&vxp=mtr

I'm not sure why you are trying to diagnose it. Your best option is to go back to the dealer and claim fraudulent selling and see if they will put it right. You're looking at a major engine repair or replacement here. Not an oil pump replacement. Think >>$4,000.00 of repairs. Mark Rechtin - Automotive News - January 8, 2007 - LOS ANGELES -- Toyota Motor Sales U.S.A. Inc. has quietly settled a class-action lawsuit that covers about 3.5 million Toyota and Lexus vehicles that may have been damaged by engine oil sludge. Details of the settlement, which allows for third-party mediation of sludge claims rejected by Toyota, have been mailed to 7.5 million current and previous owners. Critics contend Toyota has told customers and dealers too little about sludge issues. They say some customers took vehicles with dead engines to dealers who had little or no knowledge of the problem and often assumed it was the owners' fault. Unhappy customers had no remedy other than hiring a lawyer to go after Toyota. Under the agreement, owners whose claims have been denied by Toyota may submit them to a third-party mediator at no cost for binding arbitration. "This settlement breathes life into claims that have been dead for years," said Gary Gambel, a lawyer for plaintiffs who sued Toyota. "This is not a settlement that gives a few dollars to everyone. The relief is exactly tied to the problems and damages that someone might have." About 3.3 million Toyota vehicles are susceptible to oil sludge, which can cause thousands of dollars in damage and require replacement of the engine. Sludge is gelled oil that fails to lubricate engine parts. It can lead to damage, often requiring a new engine at a cost that can exceed $10,000. Complaints about sludged engines have plagued several carmakers, but Toyota's troubles have been especially controversial in light of its reputation for vehicle quality. The issue highlights a possible !Removed! in the company's armor. Executives fear Toyota is growing too fast for its engineering resources. That could lead to quality snags and a tarnished reputation. When a customer takes a sludge-caked engine to a dealership, there is usually a "clean-out" procedure. The head is pulled and a service technician tries try to steam out the sludge. If that doesn't work, the engine must be replaced. Sludge can result from poor engine design; overly tight tolerances between moving parts; improper cooling; and poor maintenance by consumers. Toyota insists the problem arises mainly when owners fail to change their oil frequently enough. The agreement does not find Toyota at fault. Damages that can be recovered include loss in value of the vehicle and incidental costs, such as rental cars. Past lawyers' fees, mental anguish and bodily injuries are not covered. A Toyota spokesman said the agreement is not a defeat for the automaker. "The settlement validates the customer support program we implemented four years ago," Xavier Dominicis said. "The terms of the program remain unchanged. There always was a way for customers to appeal our decision." Plaintiff lawyers disagree. They say Toyota failed to communicate the extent of the problem to its dealers and customers. Toyota's appeal process also meant hiring a lawyer, which many consumers could not afford. It costs nothing to file an appeal with Ates. "The consumer only needs to show reasonable maintenance in terms of oil changes," Gambel said. "You don't need to prove where the sludge came from, or explain your driving habits. If you have oil sludge, Toyota pays" the consumer.

I tried to get into the NAV service screen to disable the speed lockout on my cars NAV system. I have done it before but not for a couple of years. It doesn't seem to work anymore. Wondering if my newer MAP database disables that screen. I never get to the screen for step 7 below. Any ideas? The procedure I was trying was: Press Menu Hard Button to right of screen Press Volume Box now showing on screen Press Upper Left corner of screen Press Lower Left corner of screen Press Upper Left corner of screen Press Lower Left corner of screen Press and hold override button now showing on the screen until it beeps and changes color Hit back button showing on the screen in upper right This only works for until the key is turned off. You need to repeat the procedure each time the car is started.