95LS400Bob

Above the glovebox. Way up in there. Remove glovebox to get to it and stand on your head.

I haven't checked the ECU model in my car yet, but I'll let you know when I have. My car is actually from Singapore (I'm in N.Z.), so I'm wondering which model ECU I have.

I too believe that there is some kind of issue relating to component age, and the idle problem only becomes apparent after the car has done some significant mileage.

Perhaps we have a combination of ECU code limitation, fuel supply (filter?) issue, ICV getting dirty, blocked air cleaner etc.

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I also wondered about a combination of problems...but....the car runs perfectly and idles perfectly at all other times. No other issues whatsoever. If I had different issue like air filter, dirty icv or fuel supply probelms...surely I would think I would see some type of problem at other times.

I just wanted to throw in that I have been on several highway trips since changing to the 89661-50224 ECU in late April and no problems. I have several more highway trips over the next few weeks  so if anything changes I will certainly post. I hate to see this thread keep poping back up. Hopefully we can nail the problem down.

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So in reading your posts:

1. You had the dying problem on a 1200 mile trip.

2. You changed your cal ecu to a 49 state ecu 50224.

3, This fixed the dying problem.

Am I correct?

My original ecu 50231 did it. I changed to a 50221 and that fixed it. But then it went back to dying again.

Since I have had my throttle control valve apart and checked it in every way I still believe this is an ECU issue.

If it were a reflash issue then everybodys car would be dying that didn't have the reflash and that does not seem the case. I think it is a component issue inside the ECU...something breaking down. The only way I know that I could help prove this is to drive the car on the highway until it get's to it's "dying mode". Keep the car running by light foot throttle and pull it safely off the road and then let it die. Then take the idle contol valve apart and check that it is closed (or nearly closed...thus the 200 rpm idle).

Rather than chase ECU's I may come up with my own throttle control unit.

You are right. I forgot about the different fittings.

R-12 is about $30 a lb. R-134a is much cheaper. Probably wrote the info on the ticket wrong.

Please chose the closest description to what your car does. Elaborate all you want. :D

A fuel filter, engine temp sensor or pcv valve if faulty would cause problems.....but would have nothing to do with the "20 minute highway drive or longer" before acting up.

Haven't gotten time to take another highway cruise for the problem to happen so I can try to catch the problem. The wife drives the car every day...all over town...and never a problem.

What we thought fixed the problem did not. Or maybe it went back to dying. Read my previous posts in this thread and then this update below:

In recap:

My 1995 Ls would die after a highway cruise of 20 minutes or more. I suspected an ECU problem because all else checked out. I changed the ECU (which was a cal emissions model) to a 49 state emissions model and picked up power and mileage.

A test drive of over 60 miles after this change and the engine did not die, I figured the problem solved. But now it is back.

I had to go on an 1150 mile trip Saturday...in fact...over the same highways where the Lexus died before. The first town was 70 miles away and the Lexus was idling fine this time (where it died before). :)

I figured again....I had fixed the problem.

But the next town at 140 miles into the trip...It died while making a slow left turn in town. Started right back up and idled normally. Just like it never happened.

So from there...I started to watch that idle rpm in each town. All I can say is that it takes longer (more miles traveled) for the "dying" to happen.

However....we have discovered that if the climate control is in the auto position and therefore the air conditioning compressor is engaged....the engine will not die.

:whistles: It just so happened it was 104 degrees where we were going and as long as the ac was on...there was never a problem. I know this sounds nuts...but it is true.

The car runs perfectly and mileage is great with no other problems. I have rigged up a testing device to help me catch what is happening when the engine dies after the highway cruise. I don't give up and I will find it. Just stay tuned.

Park Place Lexus shows Idle speed control for $525.79. 93-94 Ls400 only.

Be brave. Take it apart and look at it. I did and there was nothing wrong with mine. Might be electrical connection or ecu instead.

Well I left a charger on all night and the battery did not charge. put in a new one this morning and all is well.

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Today's batterys die very strange. And young.

Yes. Or the battery may have an internal short in it. I have seen batterys that would not jump start because they are shorted inside. The best way to check this is to remove a known battery from another vehicle and install it in your car..even temporarily..and see if the car starts.

Check headlight brightness to see if battery voltage is low.

Low voltage.

I didn't connect the negative jumper cable to a bolt to the ground, but connected it to the negative battery terminal.  My neighbour revved his engine to try to help me start (he did so for about 3 minutes) but no luck.  I checked the battery terminal connections and all is tight.  95LSBob, by saying Starter connection which location or wire are you referring to?  If I still can't get it start today I'll have it towed on monday.  It's embarrassing to see a tow truck towing a Lexus!

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You just have to follow that positive battery cable. It's going to wind up at the starter somewhere.

Battery connections, battery. Starter connection or starter. Many times light duty battery jumper cables are not enough...cheap cables won't pass enough current.

Remove battery and take it to be tested. Batterys can short or dies at anytime, especially todays batterys.

If you are not a hands on type person then I would not consider it. But if you are willing to do some of the work on the car yourself then I would consider it. Lexus parts are soooo expensive that paying labor besides is just too much.

Main thing to me would be the rest of the car. If the body, paint and interior are near perfect then the car would be a consideration. I'd say your expectation of spending $5k on the car is pretty close.

I bought a 95 that needed some work and did it all myself. I paid $4700 for the car and now have $6500 in it. And I did every bit of work myself.

Suspension work and little things.

But no tranny work. I'd figure at least $2500 to do a transmission.

And I don't buy the service managers story of seals drying out.

Just thought I would bring this to the top. Got a P0 420 code today. 1st time in a long time. Anybody ever fix the P0 420 code?

Lexus never did admit a problem with the engine dying after a long drive. Several members I contacted had the dying issue and got the new ECU's and it solved the problem.

My issue and several others was solved by changing the ECU.

But...I think everyone had a "normal" idle of 550 to 600 rpms at all other times. If your engine idle is less than that then perhaps ther eis another problem. Do the test above I listed after the long drive and see if you can keep it running with foot on the throttle...as I described.

The "jerking" issue. Mine does it very seldom with the current ECU I have in the car. It used to do it all the time. Two other members bought rebuilt ECU's from Auto Truck Electric and they both said the jerking went away and also the dying isse. Both these cars were 95's.

I'd just use a Denso oxygen sensor. Guy on Ebay was selling new ones for around $60 as I remember.

Technical Service Bulletin.

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OEM = Original Equipment Manufacturer

Once I got my ECU back from upgrading at Auto & Truck in FL I went for a short (5 mile) drive to be sure the car ran OK. The next time I drove it was a few hours later when I went to the airport to pick up my wife. The car died at the airport exit which was 32 after miles of 70MPH driving. The new ECU only had 47 miles on it and it was showing the same symptoms. It idels down to 200 or 300 almost every day on my way to work after a non stop 17 mile trip at 70MPH. It may only die once or twice a week on that leg of the daily trip.

I had always wondered if this issue was related to aging parts - otherwise it shoudl have been more visible at time of purchase and Lexus woudl have been in for a recall and/or a lot of customer dissatisfaction - a lose-lose for them and the owner. I initially thought about investigating the fuel system but I stumbled onto this thread and decided the ECU was the obvious starting point. I also couldn't reason how restarting the car would 'fix' a fuel delivery problem. Regardless, a fuel filter is cheap enough and worth doing so it's going on my list - along with spark plugs.

Speedy - can you please post a scan/copy of your receipt from the dealership so we can see specifically what 'related sensors...and other parts that are in relation to pumping fuel from the fueltank to the engine and "giving" fuel "back" to the fueltank" they serviced? Maybe it's not in English but could translate the components for us?

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If you really want to clear that it is an idle issue and ECU issue, then here is a test for you. This is what I would do.

Record the idle rpm with the car in gear and foot on the brake. It should be around 600 rpm.

Now go drive to the same place it died on you....the airport....only this time you know it is going to die. So...hold your foot just slightly on the throttle peddle as you stop. Hold that rpm to around 600 rpm with your foot.

Now..let off the throttle. You'll probably see 200 rpm or a slight engine surging...and then the engine will die. Let it die.

Turn the key off, then restart the car. Back in gear and foot on the brake. Got 600 rpm again? Then it's an ECU problem. You just reset the ecu when you restarted.

Spark plugs, fuel filters and such do not "come back" with a restart of the engine.

And I agree...I think it is and "age" problem with the electronic ECU.

Same price here in Sparks, Nevada. Be sure to shop prices on glass...lot of different prices between shops.

i have only 1 fan and ive never seen it working even during the hottest days and my car never overheated. there is a sensor that connects to the radiator you might have it checked in case you want to, but AC and engine have separate radiators and they are not connected in any way, so your car will neveroverheat coz of the AC

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Ditto for me. Never seen my 95 come on either. I worried about that and so one day I went in there and checked everything there was to check. Bypassed the temp sensor in the radiator and the fan came on. Then I even removed the sensor from the radiator and warmed it up with a propane torch...and the fan once again came on. So....I know mine works..guess it is never needed.

Technical Service Bulletin.

I could make mine do it at 65 miles of cruising. Shorter peiods it just would not do it. The only way I knew I got it was drive the same distance...in fact..I went to the same town right where it died before. Turned around and came back...even went 20 miles further and it was still o.k. Then I knew I had it.

Speed may be a player..keep it at least 60 mph.

I just returned from buying my Californian 95 LS400 and have expeienced the same problem, coming off the interstate and dying on the offramp. Really dangerous! Im really interested in reading any updates from owners switching from the Californian ECM to the 49 state ECM. Any problems poped up? Improving the performance would be an added bonus. A serious thanks goes to all that have helped on this thread. I will follow up with my experience soon.

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I'm probably the only nut that tried it. :D Worked great for us...more power for sure and still passes smog no sweat. Wife drives it every day and she was the one who commented "more power".