Banshee365

It's just amazing how many problems a bad ECM can cause. My '96 also had a bad ECM which I replaced for $200 from a low miles wrecked LS. I had low idle, high idle, would flood every hot start attempt, ran horrible hot, P0115 ECT circuit malfunction, gas smell, smoke from exhaust, etc... and the new ECM cleared them all right up. I have began to think ECM's are wear items on these cars and tend to go out with higher mileage cars? I'd guess your car is over 200k with a bad ECM? Mine went out just over 200k. The guy I bought the ECM from say's he see's alot of 94 and 96 ECM's go bad that have high mileage. Funny how an electronic part can have a mileage/use based life.

Boy, you are sure quick to slam my technique while working on an issue with my car on another forum. Yet when you have an issue you WANT you answer and you WANT IT NOW! When someone doesn't give you your answer ASAP you've got to come back with some smart remark in a post afterwards to make yourself feel better. I wish you would see how big of a jack@$$ you are in your posts. Quit with all of this "I guess not...", and "not that anyone cares" because you keep acting this way, and nobody will. I already don't...

I'm with CuriousB... Clean the TB first and try it. If the problem remains clean the IACV. If you remove the TB to clean plan on replacing the gasket, mine didn't come off in one piece. Cleaning the TB is a very common procedure on the LS and usually owners rant and rave about the difference. However, some will also say it didn't make any difference but at least that would be done. BTW turning on the A/C engages and idle-up circuit so that is normal. Some mask a low idle issue but running the A/C all of the time, I don't think that is how a Lexus owner should roll!

FYI Mobil 1 bottle caps tend to be lose. When you buy your oil put a good twist on all of the caps. I have forgotten to do that and with the bottles on their sides in my trunk on the way home I lost a bit of brand new oil. Alway's use the dipstick to measure if your quantity is right, don't just go by how much you pour in. Pour in 6 qts, start the car for about 10 seconds or so and shut it off. Check the dipstick again and add more if you have to.

I've never seen a plastic trans pan so I doubt it.

With attitude like that I'm sure that person will be getting a heck of a deal. If you want a 100% reliable car just go buy a newer Honda or something with crank up windows and manual transmission. With a luxury car you'll have issues like this, especially with a 20 year old car. Sounds like you may need a newer Japanese car if you're getting frustrated with repairs.

I wouldn't let a shop do a power flush on your car. If you aren't going to do it yourself just stick with a Toyota dealer. Stay far away from jiffy-lube type places with your LS, regardless of the age. They'll top off you power steering with power steering fluid, flush with Mercon fluid and put some trashy oil filter on it. Is your transmission causing you any problems? I'll suggest you something that's easier than an oil change if you do your own oil changes, which I highly recommend. Just drain your tranmission pan and refill during every oil change, which I do every 7,500 mi with synthetic oil. I don't recall the exact number of quarts but it's a few. It's better than nothing. It will at least give you piece of mind that you're getting some of the old ATF replaced with new. Make sure to use ONLY TOYOTA TYPE-IV FLUID. Some people will swear not to flush ATF in older cars if the transmission is working fine because they think that flushing it removes metal particles that the trans is depending on for friction and will cause it to slip. I've flushed a 1996 Taurus with over 100k myself that had the original ATF in it and the trans felt better afterward. I didn't not do a power flush, however. I have flushed my 1996 with 200k by removing the line into the radiator and letting it fill up a bucket while pouring in new Type-IV to replace it. I had more piece of mind by doing that, the trans runs great, but it didn't give me any problems before. If I was in your shoes somewhat unsure of what to do and wanted an easy and cheap way to get a little bit of piece of mind about your transmission I would just drain the pan every oil change for a while and refill with Type-IV and know that you're at least better off then you were before. That will at least get some new fluid in there with the full strength, new additives to keep the seals pliable and such. -Kelly

Make sure to just goto your local Toyota parts dept. and get an OE thermostat with the jiggle valve. Should be less than $25. I think the OE thermostat is far superior than an aftermarket part that's built to fit a hundred different engines. The jiggle valve is a pretty important part to the 1UZ cooling system and must be installed at 12 o'clock.

So you've already changed the ECT sensor? I'd do that way before the coil. I don't see the coil being an issue if it's running at all, but maybe, who knows. They're known to be pretty stout. You may have some luck with the b and c sensors but they're not known to cause many problems on these cars.

Hope you used Type-IV transmission fluid and not just generic fluid in your LS400. If you did I would recommend that whoever flushed it for your flush it again with the right stuff. Hope you get things worked out with it soon. It is a great car. I have the same year.

Keep in mind that the cluster temp gauge and ECM information come from two different sensors. If your car is idling very high and getting bad gas mileage while the gauge stays in the cool range suspect the thermostat. If your gas mileage still sucks and it idles high with your gauge in the normal range suspect the ECT sensor. FWIW my '96 temp gauge doesn't go above the halfway mark. If you replace your thermostat just goto the Toyota parts department and stay away from chain autoparts stores. They're cheap at the dealer don't worry. They may be cheaper at an autoparts store but you need the OEM part. It has a jiggle valve which must be installed at the 12 o'clock position to get as much air out of the system as possible. Most all aftermarket thermostat's do not have the jiggle valve.

The fuel is cut at 2k rpm's when the TPS sensor idle position. The ECM will not let the "idle" above 2k. It will bounce because the fuel is cut at 2k and reintroduced at a lower rpm. My '96 did this as well as a very high idle when it wasn't doing this. Have you ruled out your Idle Air Control Valve? They're known to cause some issues. You can tell if it's actuating without removing the sucker by having someone sit in the car and start it then shut it off. With your head near the IACV you'll hear it click back to the open position. If you hear no clicking it may be jammed, it's not very loud. IACV's are VERY expensive. I had this same problem and my IACV was fine. I removed it and it actuated per the book. Funny thing is, my factory manual's do not show a troubleshoot procedue for P0340 in the engine diagnostics section... Do you have any friends with repair shops with scanners that can read real-time sensor data? The idle is decided by several things including ECT (Engine Coolant Temperature.) Unplug your ECT sensor. It is green in color and located under your plug wire bridge. You may have to losen your pass. side timing belt/plug wire cover to get some room to lift the bridge up a little. When you unplug your ECT the ECM assumes the engine temp is 176*F. It should cold start really really bad but run good when it's warmed up. It's going to be tough trying this in the cold weather, may have to wait until it warms up. a little. The ECT sensor is a good one to replace if the car is high miles and has the original sensor. It really controls alot. Alot of owners have reported better gas mileage with new sensors as well because with a sensor that reads cold the car thinks it's not warming up and continues to run rich. How many miles are on your car? My '96 had an enormous amount of general running conditions including: Super high idle, sometimes super low idle, very rich running, hard to hot start, floods easily, smells like rotten eggs out of the exhaust, P0115 ECT circuit manfunction codes, poor power and bad gas mileage to name a few. All of these were caused by a bad ECM. I replaced the ECM with a good low miles unit for a couple hundred bucks and it's like a new car. Every problem it had running wise is gone and it runs like a sewing machine. I know you may hate to hear that your ECM may be bad but there are options. In the factory manuals, if all checks of sensors associated with a certain code are checked good then the last step is usually to replace the ECM. The ECM can be throwing a code that it's causing while the circuit/sensor is operating just fine. With mine, the source voltage was running really high on the ECT circuit and made the ECM thing the car was very cold no matter what when the sensor and circuit had good info going INTO the ECM. Yet it threw a code saying there is a problem with the sensor or circuit. Don't be fooled very easily. The 94 and 96 ECM's are known to go bad with mileage/age. Don't suspect the worst but it is a possibility. If, in fact, your ECM is found to be the problem there are a couple of shops that fix circuits for around $400. If you are lucky enough to find a ECM that matches your model year like I did that will be your best bet. -Kelly

I might suspect the selenoid itself if it's coming and going. Test it by pulling it off and connecting a 12v DC source to each lead and make sure it clicks and cycles. BTW, for future referance, if you want to pull the res. without making a huge mess just drop the solenoid and let the fluid drain into a pan. You should mostly empty the res. doing that and make the process alot cleaner than removing a full res.

Other common knocking problems are caused by worn lower control arm bushings, strut rod bushings, and upper control arms bushings. I would lean more towards the strut bar bushings for now. They are replacable with factory bushings and are pressed in the strut rods. Have someone stand next to you front tire with the car in drive and let it roll and slam on the brakes a few times like you're trying to make the front end dive down or make your passanger hit the windshield. If the observer see's the tire moving fore and aft in the wheel well your strut rod bushings are bad. -Kelly

If you didn't know to check the fuse I think you should know something. If you find that the fuse is blown, and it blows an exact replacement again. That doesn't mean that installing a bigger fuse fixes the problem. If the fuse keeps blowing there is probably a short or something in the receptical somewhere. I had the same problem and I noticed little pieces of metal down in the receptical that came from a broken accessory and they were causing the fuse to blow by shorting the circuit. Exactly why the fuse is there.

First of all, lay off the caps dude. And you won't get any replies spamming like that... Do some searching and quit spamming the forums, it's really rude. You have 3 posts, all of which are on this same thread. You joined 2 months ago and had nothing to add to the forum but your capital letters and demanding help...

Remove PPS solenoid from the drivers side. Fix connector above solenoid when removing to keep fluid out of the connector. Be sure to place a drain pan under it as your PS fluid will pretty much all drain out. Clean the screen on the solenoid as is discussed alot on this forums. Make sure the solenoid move freely by spraying some WD40 or similar and using a small nail or something to stick in the end to make sure the solenoid is moving freely. I did this because of really hard steering and now it steers with one finger. Be sure to fill the res. with ATF after you install the solenoid. Bet this is your problem.

Yea, was planning to take some pics not just for reference for me but who others who may have to do this common repair on our cars. However, I'm still looking for information if the seats, rear seat backs, third brake light, side pillar trim, etc... has to come out. I've also read of early model LS evaporator's coming out of the passangers side floor board without taking the dash apart. I'm assuming since the factory manual say's to take the whole dash apart, that that's what will have to happen. I just need to figure out of the rest has to come apart.

Getting ready to replace the compressor and evaporator core this week. The factory manuals lead to removing the front seats, rear seat backs, all side trim, 3rd brake light, side pillar trim, steering wheel, entire dash and dash brace. All of this to get the AC unit out from behind the dash. I've read on some forums of guy's just removing the glovebox, blower, etc and just pulling the evaporator from the passangers side floorboard. Is this possible on the '96 or does the entire interior of the car have to be taken apart? I'm assuming I can at most remove the front seats and the steering wheel/column and dash to remove the whole AC unit to take it apart and get the evaporator out. I don't mind doing the work but don't want to risk breakin parts all over the interior of the car when I don't have to. Have at least 2 full day's to get this done, hoping it goes well. Any input? -Kelly

Well, that may have been your issue but is far from 99% of causes for leaks. Most A/C leaks on most cars with old age and high miles tend to be compressor front seals. For the LS400 the evaporator core also tends to start leaking. Not a fun repair. My 96 has both leaks right now and I'm still saving for the parts, haha.

Any clunking? If you've never replaced any parts I'd assume your due for some replacements. Are you looking for purely OEM parts? I would recommend that. You'll probably be looking at upper control arms, lower control arms (unless you don't mind doing aftermarket poly bushings, lower ball joinds, and strut rod bushings which must be pressed out. Be sure to know that poly bushings will squeek unles they're greased properly and possibly regreased throughout the use of the car. I know this from experience with lower control arm bushings. I bought most of my parts from Carson Toyota. Also look into Lexus of Pembrooke Pines in S. FL. I got the best price on OEM lower ball joints from eBay believe it or not. Lot's of threads on here about suspension parts as well.

I installed the plugs, caps, rotors, and wires about 2 years ago. It ran fine until now. When it's running all cylinders are firing. It smells like rotten eggs after it's flooded out and you can finally get it started after it sits for a while. It seems to be strictly a fuel metering issue since the ignition fires fine when the engine is running. Even up to high revs, it's smoth as can be. I had the car hooked up to a snap-on scanner a few weeks ago and it wasn't showing a single bit of misfiring. If it wasn't for the coolant temp circuit malfunction CEL i wouldn't blame the ECU for anything. But with a new sensor and a good harness even the factory manuals say to replace the ECU. If the CEL wasn't there I would look more at the MAF sensor and o2 sensors. I'm guessing it's one of those 3 that's messing things up. Are the 96 models also effected by the trunk wiring harness?

it's a '96 LS with 203k. New plugs, wires, caps, rotors. Never a code for the MAF. Had an intermittent code for an o2 sensor but it hasn't come back. Could I unplug the MAF and see how it runs? Some say their car runs better with it unplugged if it's bad. I could at least do that to maybe troubleshoot it and replace it if it's bad. The car is running soo horrible. The idle is just out of control then it starts running really rich. How can I tell if it's running in limp mode? When it's running all 8 cylinders fire fine. It just idles super duper high then starts running rich to where when you shut it down it won't start back up until it cools. I'm so stumped.

I do not have any current o2 sensor codes. Only the coolant temp circuit malfunction. The car will no drive reliably enough to leave my driveway without it shutting down, flooding out, and not restarting until it sits long enough to finally crank up and blow black smoke out the back. That's why I think it's running rich. I wish there was a light (no trac control) on this car that would indicate it's operating in limp mode. The car will also hesitate off idle when you rev it, even at 1,200 rpm idle. That's another indication to me it's running rich. It does all this while smelling like rotten eggs. I can't afford to go replacing $300-$400 in o2 sensors just in case they might be bad. I've cleaned the throttle body recently and cleaned and checked the operation of the IACV. The IACV on the '96 does not come apart like the Gen 1's so all you can do is cleaned the plunger with some carb cleaner and a wire brush attatchment on a drill. What's triggering my suspision of the ECU is the intermittent coolant temp circuit malfunction CEL that cannot be duplicated by wiggling wires and such over the sensor. This thing is driving me nutty!

I could see those being issues as far as the high idling goes. What about the running really really rich and being hard to start when warm? Smells like rotten eggs too. And the CEL for engine coolant temp circuit manfunction even with a brand new sensor. Should I start suspecting the ECU?