landar

I am leaning towards engine mounts which might let the engine bang or clank against worn mounts when unloaded in park or neutral but held more in place when torqued slightly being in drive. Maybe even worn transmission mounts.

Well, its a 94 not a 98 so it is not as advanced but I would still want the ECM/PCM out of the 94 model for compatibility reasons.

Might be as serious as a heart attack. Thats what I would have had if mine did that. White smoke 'usually' means coolant or power steering fluid being combusted. Maybe a gross leakage into a cylinder causing knocking? As a start, carefully check and note all of your fluid levels to see if one is very low. Check the timing belt. Has it recently been changed?

There is a lot of stuff to remove to get at the valve covers. Plus add some time if you want the spark plug gaskets replaced. I would ballpark it at 5 hours. Sounds high but does take some doing depending on the mechanics familiarity with the LS400. 5 hrs x $50/hr = $250 + parts = $300-$350 (ballpark)

The few times I have taken my vehicles to a shop for an oil change, I ALWAYS immediately pull the car into a parking space, shut off the engine and pop the hood. I check the oil level and have a peak at the oil filter to make sure 1) it was replaced 2) is not leaking. I am a trusting sole in that way..not. ;) I cannot see how a leaking valve cover gasket would affect tailpipe smog output. It might produce 'smog' around the exhaust manifold but thats it.

I would agree with Billy that the starter is not the main problem, although I would not rule out a starter issue but it is not your MAIN issue. Your ignition switch could also be suspect. Now, the fast cranking and symptoms of compression loss are most troubling. I would have bet on a broken timing belt but you indicate that it is fine. First, I would check for computer codes. If none, check for compression. You might remove the valve covers and check for movement. Maybe a cam key is broken and it is not really turning?

And I am guessing that the fuse still blew @ 20 A? Of course, you realize the dangers of replacing a fuse with a higher than designed value. Potentially burned wires. I am wondering if the circuit in question also runs the compressor clutch. If the clutch coil were partially shorted or otherwise compromised, it could still work but might draw more current than it should.

Filter partially clogged? Unless you live in Minnesota and this was a -50 F day...that could explain it. ^_^

I am not sure what a booster box is and why positive to neg and vice versa. When you jump or boost a battery, it is positive to positive, negative to negative. Otherwise, 'spritzen sparken' results. Its a parallel (not series) connection. If the car starts with jumper cables and the battery is good... then, most likely, the battery clamp connection(s) are simply dirty. Remove those, clean and reassemble.

Mike, sorry to hear that you have not found joy as of yet. As for the Seafoam...surely you jest. There are posts ad nauseam about using Seafoam. Not only on this forum but every automotive forum on the web. Many owners love the stuff but I would not even consider using it on my LS. Seafoam is basically just Acetone in a bottle touted as a magic elixir. Its a volatile subject.

Take a look at this site -> http://custombattery...do_you_need.htm The nomenclature is #1/0 = single zero("aught" or "ought"), 2/0 = double zero, etc...the lower the number or more zeros, the bigger the diameter. There is also a link to wire gauge size at the bottom of the page. You can measure your existing cable and match it up if you want to buy exact sized clamps.

Looks like you triple clutched on this post, greek. ;) Anyway, you have spark and fuel but still no go? If the cam timing is correct and you have compression, you should have all the magic sauce to make it run. I would go back and look for a sensor connector that you forgot to put back together when you performed the work.

It does sound like IR loss. Check the wires that come into the battery post clamps. Sometimes a high z connection develops there where the wires meet the clamp heads. With several heavy electrical loads on (headlights, seats, defroster) you might feel some excessive heat at one of the battery terminals with your hand. They should be stone cold.

See if these pics help any -> http://www.lexls.com/tutorials/steering/psflush.html

There is a whole post on this, John. Turns out there is also a fuse built right into the back of the cigarette socket. You may be missing that. Try a search and you will see. Welcome to the club. Edit: Here 'tis -> http://us.lexusowner...=1

Could be your thermostat sticking open. Or a bad temperature sensor. How long does it take for the engine to warm to "normal" temperature? (also please specify your ambient temperature as well because that factors into the warmup time). Man, thats low miles(100k) for a 95. Have you, or past owner, changed the original timing belt?

It could be a mount, bushing or joint along the driveshaft line. The transmission mounts are notorious for cracking. Changing that mount is fairly easy and almost a maintenance item if it has not been performed in the last 8 years or so. If you are handy and do your own work, you would need to crawl under the car and do some inspecting. Or what I would do, and is much safer and more convenient, is take the car to a trusted shop and explain the issue to them. They can easily put it on a lift, do a quick inspection and probably tell you what the problem is. Then you can decide if you want to tackle the fix or have them do it. Most shops will do the inspection for free and if not, it is only a few bucks.

Welcome to the club, Elisa! The answer is yes, with the help of a mechanic you can get it replaced. It is really not all that difficult. You will need to determine if the tensioner pulley seized or the fan bracket pulley. Again, welcome.

Thoughts? Yes. Replace ALL of your ignition wires, not just a select one or two. If they are original, they have been "baking" in that engine compartment for the past 18 years. Retire all of them. Ditto for the caps and rotors.

Intermittent problems act just the way you have described the symptoms. Your old alternator could still be bad at times. Perhaps an internal diode is opening up (open circuit) when it gets hot. In any case, I would check your charging system very carefully to determine the root cause. There are literally dozens of videos and tutorials online describing how to use a simple VOM to check the charging system. If you do a thorough search on this site, you will see many threads devoted to issues such as you are seeing. Then sit back and enjoy the reading. If you do not feel confident in checking your charging system yourself, you can take your car to most auto centers and they will perform a charging system check and load testing of your battery for a small cost or possibly free.

Welcome Viker. Have you had the notorious, bizarre trunk wiring cable checked out? Although I doubt that would cause the headlights to dim. Possibly the main 120 A fuse or connection is intermittent. The most obvious place to start is with the battery and the cable post connections. Make sure the connections are clean and tight and that the battery is good.

Mike, Thanks for clearing that up. I sometimes wonder if the ECU might be the problem. Generally, and certainly in your situation, the computer is clearly functioning because the engine is running relatively well. However, the coils and fuel injector actuator need a "driver" circuit such as a power transistor(which is a peripheral circuit to the computer) and I wonder if perhaps your ECU driver (either fuel or spark) could be malfunctioning at times. Due to the misfire under load, I would have to go with the spark as it may not be driving the coil hot enough for the richer mixtures that a loaded situation would demand.

I guess you have learned a valuable lesson not to do THAT again (reverse polarity). So chalk it up to experience. From the sounds of it, you just missed replacing a fuse and will need to methodically track them all down and test. I just hope you did not whack a control computer somewhere. The radio not working should make it relatively easy to check the radio fuse. And make sure to use a continuity tester to check the fuses, like an ohmmeter or test light. Sometimes a visual check looks ok but is not. Do the cigarette lighters work?

Oh drool.... why do you do this to us Billy??? He is about $2k too high in price but it sure looks nice. How far away is it from your location?

Oftentimes when facing a mysterious problem, I find the little clues to be most revealing. And you do reiterate the above clue as well...so it might merit more investigation. If this misfire goes away as soon as you put a load on the engine then it has me thinking injector or slight manifold leak. On the other hand, you mention that P0301 happens with petrol or propane, correct? Are there two separate injectors for each fuel system? If so, then the injector most likely is not the culprit. If the injector is shared, then perhaps the injector "sticks", when cold and lightly used, until it gets a bigger electrical "kick" from the ECU, which would happen under load. Then again, perhaps there is an air leak at the manifold at cylinder #1 that seals when the engine warms. Under load, the air leaking in would be insignificant compared to the throttle air which might make the misfire disappear for the moment. I know you have performed the propane test once but I would encourage you to grab that bottle again and specifically concentrate on the intake manifold sealing surfaces of cylinder #1. I may not be understanding your comments because I just noticed in your first post that you say "This would happen ONLY when the engine was completely cold AND under load - eg. pulling uphill at low revs." Seems to be in conflict with the quote above. Can you verify/clarify? Thanks.