95/96 Ls400 Low Idle, Engine Dies And Jerking Thre

[yidaitianjiaous]

I just replaced my ECM for a 93 ls400 and it cost me $175 + $35 overnight shipping. You just send your ecm/ecu to the place, and they fix it for you if possible and return it. the site is www.autocomputersupply.com they are located in houston, tx. hope this helps

God Bless you!! I live in houston and should be able to drive my 94 LS400 down there and get it fixed. SWEET!!!

I have a 92 LS400 165K, idle is always at berween 400-600, looks like lower than 600 but also seems like 400. is that normal? used to have one stall after off fwy.

[pishta]

I just replaced my ECM for a 93 ls400 and it cost me $175 + $35 overnight shipping. You just send your ecm/ecu to the place, and they fix it for you if possible and return it. the site is www.autocomputersupply.com they are located in houston, tx. hope this helps

God Bless you!! I live in houston and should be able to drive my 94 LS400 down there and get it fixed. SWEET!!!

I have a 92 LS400 165K, idle is always at berween 400-600, looks like lower than 600 but also seems like 400. is that normal? used to have one stall after off fwy.

check the TPS on the throttle body. You can turn it (adjust it) to get your idle back to 750. There is a measurement that you can take, its explained in the manual or you can look it up as it has a picture associated with it to assist you in adjusting it.

[lexamainia]

hi, i have 92 ls400 with pretty much the same problem like 95-96'rs. it just started for the first time yesterday got about 185km, pulled out the IAC cleaned it seems like its working just fine. checked all the vac lines. tried adjusting tps too but no luck( it just starts up revs up to in between 2000 to 2500 and comes back to normal idle at 600 and then dies out, and when its on the normal temp rpm rev up and down, some time almost dies out and then revs back up . plz advise.

[JWH]

Here's the results after a 70 mile run at 80 mph non stop.

Be sure to read the entire thread. These are the results of replacing my Calif ecu 89661-50231 with a 49 state ecu 89661-50221.

The car idles 600 rpm..absolute steady..not a waver on the tach. Even after the sustained highway driving (it used to die at idle.) This proves my problem was the ecu.

The car has much better power everywhere from stoplight to stoplight or accelerating on the highway. This shows the Cali ecu's are as suspected...cut back on engine performance.

The jerking that happened when closing the throttle and then getting back on the throttle at around 45 mph has only occured once with the 49 state ecu and it was nowhere near as harsh.

So I will now return this borrowed ecu and hunt down a 49 state unit and install it in my car...or will go for the "improved" ecu if I find one at a reasonable price.

Hope this helps someone in the future.

[afcsdbt]

The ECU and dying problem was more related to the 95 and 96's from all the research I did. And that was after a highway cruise....otherwise it never happened.

................................Hope this helps a little. These intermittent problems can be a bugger to find.

95LS400Bob

I am impressed!!! I have been looking for a solution for the last 2- 3 years on this low idle, sudden engine shut off during Highway travel for 30 minutes etc… I have described exactly the very same issue on the other Lexus user side and to the dealer and no one could help me at all !!!!!

I have a 95 LS400 model, got it with 45K a few years ago….. and had this issue ever since … what got it solved temporarily was an injector clearing by the dealer for about 8 month… then started over again.. I even used the sea foam through the vac-booster line and fix/ help it for about 1800 miles .. but it’s back again….

Now, my question, how to I get the current ECM number … I looked and could not find it right away… then, how do I approach the dealer with this issue? Is there bulletin service number on that such that I can point to it?

What is my lowest cost and reliable option here?

Many thanks

[yoichisoma]

This is good thread from LS400bob. My 95LS did the same thing. I had the original ECU "rebuilt" but it did not fix the problem. Just to be sure, I looked up the TSB technical service bulletin on TIS (Toyota Service Support website) paid 10dollars for a day pass and looked up the correct part numbers. They have been superceded a few times. It says to change the cruise control computer too, but I did not do that. I took the part number and did a web search for a junkyard ECU and got it for 200 or so I forgot the exact price. A new ECU runs well over a grand. No problems with the car ever since.

Yo

[DLs22]

Hey there, B) Having the same problems here... Just wondering what ECU# did you replace it with?

[t3honion]

hello, i just got my 95 ls400 about 2 months ago, and it has not been dying, but i did notice a unusual 300-500 rpm range when idle for the last week or so. i have noticed the car studder when letting of the gas at around 45 and then giving it gas, like it didnt know what to do for a second.

I am looking into purcasing an ECM i found on e-bay for 150.00$ "1995 LEXUS LS400 ENGINE CONTROL COMPUTER.PART# 89661-50234" Is this the right one for my car? I'm going to need to make sure i have an outdated ecm first as you guys said earlier in the post this MAY not be the problem.

[dwid5252]

Here's an update:

I received the rebuilt ECU for my 96, took 2 hrs to install (removing glovebox and other hard to get to screws and bolts. Then drove it on a 2hr freeway drive non-stop, got off the freeway and braked very hard to a stop...tach stayed at 600-650!

So it seems the ecu did the trick, if anyone needs help on how to remove the glovebox/ecu I can walk you through it.

I could use some help with the removal of the glovebox.

[yoichisoma]

Guys,

It is worth looking at the TSB on the TIS site. It cost 10 dollars a day to sign in and you can print manuals and look up TSBs. It says exactly which models are affected and exactly what ECU to buy and the dealer will know if the ECU in the TSB has been superceded by another part number. Take that part number and do a google search and you will find wrecking yards that have the exact part. Forgot how to take the glovebox apart, but screws are usually hidden behind plastic caps. It is pretty tight and you will need 1/4 inch rachets and extensions, long 10mm sockets and might be easier if you remove passenger seat for body access unless you are a contortionist.

Yo Gold 95 LS400 145k

[blake918]

Here's the TSB with the part numbers....

41.pdf

[DLs22]

Here's the TSB with the part numbers....

right one pimp-in! B)

[danmac]

I am trying to make a thread here for the many of those with low idle, engine quits after an extended highway cruise when coming to a stop, and a mysterious drivetrain jerk when you let off the throttle and get back on....sometimes...and usually happening over 40 mph.

My 95 Ls400 built april of 95 which now has 150,000 miles has these problems.

I've done full diagnostics. I've gone after the throttle body and the Idle control valve. All of which were working perfectly. After 3 days of reading threads at several different forums of similar problems with 95's, several emails and follow ups on who found what the problem was and how solved I wanted to put all the information here so the next guy could find it easier.

Some guys are driving around with the a/c on to keep the engine running at a faster idle to keep the car from dying.

I'm convinced all 3 problems are related to the ECM and it's controlling of the idle air control. While there were a couple of TSB's on this it was never a recall. Those of us who bought used or have high miles are out of luck for any dealer help...at least I would think.

Your Ecm is located behind the glovebox on the passenger side. If you want to read what number Ecm you have..you can do that by not removing it. Just remove the lower plastic panel below the glovebox and look up in there. You'll see "Engine Computer Label" and the numbers.

For 1995's:

Your original Ecm is either:

89661-50220 or 89661-50221 if Federal (49 state). Lexus new replacement on the TSB says to replace with 89661-50224

If California then your orginal Ecm is either 89661-50230 or 89661-50231. The TSB calls for 89661-50234

But searching a local Lexus parts site shows that number has been replaced with 89661-50235-85.

The cost of these Ecm's new is just total crazy. But there might be another solution.

One member bought a used pcm from a wrecking yard #80661-50224. He paid about $150 for it and it solved his issues. I did some searching in wrecking yards and there are some of these #'s out there.

If you have a California car then there seems to be few out there. Mine is a California car. I don't know if a 49 state Ecm will work...I suspect it will...but unknown at this time.

Another member bought a remanufactured Ecm for his 49 state car. He paid $300. for it and it has a 1 year warranty. He also stated that it cured all problems. The company he purchased it from was Auto & Truck Electronics in West Palm beach, Florida. He said the part number was #95 Int 56834. (That was a 49 state unit).

There are other places on the web where rebuilt Ecu's are sold. The problem is most are listed by the old number. We have no way of knowing if the old units are rebuilt and then "reflashed" to the later specs which we are looking for to solve these issues.

I'll try to find out about that and post here what I find out.

For 1996's: The Ecm you want is 89661-50303. Original's were 89661-50302. A wrecking yard buddy did a nationwide search and there are used 89661-50303's out there. Evidently these work in all 50 state cars.

Ps: A 1996 Ecm will not work in a 95. It turns the check engine light on. That's been tried.

Update: I just received an email from the gentleman who bought the remanufactured pcm from Auto & Truck Electronics(mentioned above). He confirmed with them that the Ecu had the latest software upgrade before he bought the Ecu. He also commented the car shifted smoother than it ever did.

Hi, Bob I have a 1993 Ls when cold it runs fine. When it warms up it jerks most of the time. Do you think its my ecm or something else. Thanks Dan danmac1219@yahoo.com

[Kiwi Dean]

My 1995 with only 115000km here in New Zealand has the same issues as described by other members.I have read with interest the therories about the ecm and the part numbers of the ecm that seem to solve the problem.My ecm is 89661-50261.Does anyone have a sure fire fix for this problem? Are there any Lexus technicians with any ideas?

[gatoman39]

Toyota Recalls 1.1 Million Cars for Engine Problem

DETROIT — Toyota Motor, the Japanese automaker, said Thursday that it would recall 1.13 million compact cars, days after federal safety regulators upgraded an investigation into numerous complaints about the cars stalling.

This sounds like the same problem that we're discussing here.

[curiousB]

I don't think its very likely Toyota or Lexus issue a recall for a 15 year old model. This recall is for 2005-2008 Corolla's. I think its a bit of stretch to suggest these are closely linked.

[gatoman39]

I don't think its very likely Toyota or Lexus issue a recall for a 15 year old model. This recall is for 2005-2008 Corolla's. I think its a bit of stretch to suggest these are closely linked.

That's what I thought too, but The NHSTA is investigating a fault on 1993–2004 Jeep Grand Cherokees

http://www.autoblog.com/2010/08/25/older-jeep-grand-cherokees-being-investigated-for-fuel-tank-defe/

[livinginlilliput]

Our 1995 LS400 has all the problems that were in the OP, and actually has had the stalling at 40 problem since we bought it. The previous owner did, too. Other than feeling like it was going to stall around 40 mph, the car has been a fantastic car and has not given us any problems.

Until now.

Two weeks ago the car stalled then totally died on a city street, after about 30 miles on the highway. We hadn't found this thread and replaced the spark plugs (original)and the coils. It was pulling codes for 300,302,303, 304, 305, 306...

It ran great! Until yesterday.

We were on our way to family for Thanksgiving (about 1 1/2 hours, about half highway) and about an hour into the trip I stopped at an intersection, and the car stalled crossing it. I managed to get it restarted and crossed the road, but then it stalled again, when I restarted it it only ran for a few more yards, and only at speeds between 10-20 mph. It was loping/surging.

Could this be the ECM issue? Or do I need to find another solution? The car ended up being towed to Thansksgiving dinner and we had all sorts of friends looking at it last night, troubleshooting, and they couldn't find anything wrong. It wouldn't start last night. Then this morning it started right up.

Does anyone have any ideas?

[landar]

Yes, this certainly is an interesting thread on ECM's. The mysterious and intermittent problems are difficult to troubleshoot and just smack of bad connection(s) somewhere. I am wondering if the ECM is really bad or the connector has developed some high resistance (ie: corrosion, tarnish, etc). The ECM is an embedded computer which runs a program. The program would not suddenly and intermittently fail per se'. However, the signals feeding the ECM could come and go and be erratic thus causing the problem(s). Perhaps some bad solder connections within the ECM? I have not yet seen where someone solves the problem with a "new" ECM, then puts the old one back in to re-verify that it was indeed the problem. It is entirely possible that the new ECM has cleaner contacts and that is all it was.

Has anyone knowledge of the actual fault within the ECM (ie: which component fails)? Would love to get my hands on a detailed ECM schematic.

Perhaps, as a start, you cold pull the ECM connector(s) and try to clean them(both ends)? Radio Shack sells a contact cleaner for this type of condition.

[kizeLS400]

im new to this site but thanks to all who have helped ouot with this onn going problem, my car has the same syptoms that these 95 ls 400's seem to have the " off throttle shock" the low idling and dieing at a stop sign or light, but somethin gdifferent happened to mine that i havent read on here, mine will start and shut rite off, and then start up and shut rite off again. if i turn it on in the morning it will run for 5 minutes and then shut off, ill turn it on , turns on then shuts off again so rite now its jsut not drivable cause it will only sta on for a minute then shutt off. im guessing i have to update the ecm, but what it causeing my to turn on and turn off? any help would be highly appreciated, thanks ,eric.

[kizeLS400]

Here's the latest. When I changed the ECU to the 49 state dealio...we drove the car over the exact same ground where it died and it was fine. Thought we got it.

Then we made a trip to Phoenix and low and behold...she dies. Only now..for some reason...instead of dying after 60 mile jaunts...you have to go about 100 miles. Strange indeed.

A few months ago we went to California...a 150 mile trip one way. Never died. Same deal on the way home. Never died.

Since the car runs flawless in every other way I just never got around to doing the $99 rebuild on the ECU. What I would like to have is the new ECU...the one I feel Lexus did to solve the problem. That is the 89661-50224. But I don't want to pay $1000 for it.

Since this is the wifes around town car anyway we are living with it. Someday I might find the new ECU in a wrecking yard with some luck.

So I think I still have the "dies after the highway cruise problem." Gas prices what they were we didn't do any long highway drives.

Once in a while..I get the check engine light. About once a year. And that always turns out to be the P0 420 code. I simply read the code with my diagnostic tool and erase it. The car passes all smog checks and reads 000 on all smog checks. I've looked at both cats and they are clear. Not going to throw money at as many others have chased this P0 code and replaced 02's and cats and still get the code from time to time.

So we drive her on.

It's the "why" that always puzzles me.

m new to this site but thanks to all who have helped ouot with this onn going problem, my car has the same syptoms that these 95 ls 400's seem to have the " off throttle shock" the low idling and dieing at a stop sign or light, but somethin gdifferent happened to mine that i havent read on here, mine will start and shut rite off, and then start up and shut rite off again. if i turn it on in the morning it will run for 5 minutes and then shut off, ill turn it on , turns on then shuts off again so rite now its jsut not drivable cause it will only sta on for a minute then shutt off. im guessing i have to update the ecm, but what it causeing my to turn on and turn off? any help would be highly appreciated, thanks ,eric.

[kizeLS400]

Man, this thread is like the freakin' energizer bunny.

If we want Lex to own up for a recall, you've got to notify the national highway safety and transportation board. There are a few notices on the issue "I think 10" to them already. I used this fact, and their own recommendation of the fact that out of all the TSB's issued for the car, this is the ONLY one LEXUS HIGHLY RECOMMENDS BE DONE! That, a few calls to Lexus USA, and some legal mumbo-jumbo to the manager of the dealership, and they caved in, paid for it to be fixed. But, my story also included a 90 day / 3,000mile warranty. I have noticed however on the 95-97 used models that dealership gets....it's now "AS IS" on the sticker! Hahahaha. Sorry guys.

m new to this site but thanks to all who have helped ouot with this onn going problem, my car has the same syptoms that these 95 ls 400's seem to have the " off throttle shock" the low idling and dieing at a stop sign or light, but somethin gdifferent happened to mine that i havent read on here, mine will start and shut rite off, and then start up and shut rite off again. if i turn it on in the morning it will run for 5 minutes and then shut off, ill turn it on , turns on then shuts off again so rite now its jsut not drivable cause it will only sta on for a minute then shutt off. im guessing i have to update the ecm, but what it causeing my to turn on and turn off? any help would be highly appreciated, thanks ,eric.

[kizeLS400]

My ls400 95 (144000 mile) is right now at the Lexus dealer with this issue, this is the second dealership that will be looking at it. The first did not fix it because they could not reproduce it.

I drive it on the freeway every day.

When I drive it for a distance greater than 30 minutes, speeds over 65, brake at a right turning off ramp, idle goes down and it stalls. The car immediately starts back up. Drives fine on the city streets, no more stalling after restarting the car.

I get the "off throttle shock" as well. Thanks for giving me something to try.

←

HI: If fuel filter/airfilter is good, injectors clean, I would go with the mass/airflow sensor, have it cleaned first and then replaced, it might just be corroded in the electrical parts.

C. PR

m new to this site but thanks to all who have helped ouot with this onn going problem, my car has the same syptoms that these 95 ls 400's seem to have the " off throttle shock" the low idling and dieing at a stop sign or light, but somethin gdifferent happened to mine that i havent read on here, mine will start and shut rite off, and then start up and shut rite off again. if i turn it on in the morning it will run for 5 minutes and then shut off, ill turn it on , turns on then shuts off again so rite now its jsut not drivable cause it will only sta on for a minute then shutt off. im guessing i have to update the ecm, but what it causeing my to turn on and turn off? any help would be highly appreciated, thanks ,eric.

[Imzjustplayin]

I can almost guarantee the issue with these ECUS stems from faulty electrolytic capacitors much like the gauge clusters that have that flickering problem.

[Andre perez]

Whats up guys loooks like this forum is gonna save my life . I have a question though i was reading the forum and it said the ecu i want for a 1996 is 89661-50303 and the original one is 89661-50302. My ecu that i have is the 89661-50303.  Does that mean someone has replaced my ecu before ?