Bogging Out/idle Hi-low

[MIKEY2TIMES]

YES I HAVE A 1990 LS400 IT BOGGED OUT ON ME THE OTHER DAY OVER AND OVER AGAIN KEPT DYING ON ME LIKE ABOUT 10 TIMES THEN I PUNCHED THE GAS PEDAL AND IT STOPPED AND ABOUT 2 MONTHS AGO THE IDLE STARTED TRIPPIN OUT GOING REAL HI THEN SHOOT BACK DOWN ABOUT TO DIE THEN SAVE ITSELF THEN SHOOT BACK UP IT DID IT FOR A ABOUT 20 MINUTES THEN BACK TO NORMAL DOES ANY NO THOSE SIGNS OR HAD IT HAPPEN TO THEM PLEASE HELP MY LS400 ONLY HAS 160000 ON IT SO ITS GOT SOME YEARS LEFT SO AGAIN PLEASE HELP THANX

MIKEY2TIMES<--------------------------------------

I FORGOT TO AD THAT WHEN THE CAR WAS TRIPPIN OUT AND THE CAR WAS BOGGING OUT THE CHECK ENGINE LIGHT CAME ON WITH ALL OF THE LIGHTS ALSO LIKE OIL LIGHT LIKE BEFORE YOU START THE CAR WHEN ALL THE LIGHTS ARE ON.

[VBdenny]

Man, the idle doing that sounds like some kind of air leak in the vacuum but who knows? What sounded strange was ALL of the lights going on? It has happened to me in the past that when I started the car ( a Cadillac) , the key didn't fully engage the ignition. The car started but did weird stuff like that. Not sure why but I attributed it to age (the cars, not mine). I would go to AUTOZONE and have them do an OBD1 check.

[yidaitianjiaous]

YES I HAVE A 1990 LS400 IT BOGGED OUT ON ME THE OTHER DAY OVER AND OVER AGAIN KEPT DYING ON ME LIKE ABOUT 10 TIMES THEN I PUNCHED THE GAS PEDAL AND IT STOPPED AND ABOUT 2 MONTHS AGO THE IDLE STARTED TRIPPIN OUT GOING REAL HI THEN SHOOT BACK DOWN ABOUT TO DIE THEN SAVE ITSELF THEN SHOOT BACK UP IT DID IT FOR A ABOUT 20 MINUTES THEN BACK TO NORMAL DOES ANY NO THOSE SIGNS OR HAD IT HAPPEN TO THEM PLEASE HELP MY LS400 ONLY HAS 160000 ON IT SO ITS GOT SOME YEARS LEFT SO AGAIN PLEASE HELP THANX

MIKEY2TIMES<--------------------------------------

I FORGOT TO AD THAT WHEN THE CAR WAS TRIPPIN OUT AND THE CAR WAS BOGGING OUT THE CHECK ENGINE LIGHT CAME ON WITH ALL OF THE LIGHTS ALSO LIKE OIL LIGHT LIKE BEFORE YOU START THE CAR WHEN ALL THE LIGHTS ARE ON.

have you solved your problems?

I had this problem after off fwy and stopped at red light. Engine stalled and up and downs several times and then died. restarted and kept on doing this. I put one foot on on brake adn one foot on feul pedal and rode to a parking lot. during morning break, i cheked it adn it started ok and engine ran perfect. no up and downs, no choking, no stroke at all. don;t know if it will do it again on my way home or some other time. btw, it's 92 ls 400, 165k.

any clues, inputs, suggestions?

[ko90ls]

prob a vacuum leak. check the throttle body gasket. mine had a very minor crack and was causing this. The reason why the lights come on is because the key is in the "ON" position but the car (alt, engine, etc) is no longer running. But the "check engine" light should come on for a split sec so there should be a diagnostic code stored. one thing about mine was that the car idled great until the engine was warm then the idle would drop out at 0 and engine dies. everything else still worked and the car would start fine, but i also had to keep a little pressure on the gas pedal to keep the idle above 0.

[R.Holmes]

prob a vacuum leak. check the throttle body gasket. mine had a very minor crack and was causing this. The reason why the lights come on is because the key is in the "ON" position but the car (alt, engine, etc) is no longer running. But the "check engine" light should come on for a split sec so there should be a diagnostic code stored. one thing about mine was that the car idled great until the engine was warm then the idle would drop out at 0 and engine dies. everything else still worked and the car would start fine, but i also had to keep a little pressure on the gas pedal to keep the idle above 0.

This sounds lilke the old familiar problem of cleaning the IAC Valve. Same symtoms.

[Mxjulian165]

I also came across a problem. I ran my 1990 Lexus LS 400 to empty and ever since I’ve been having problems with bogging and loss of power also when I start it up it almost sounds as if it’s cammed sometimes it run good sometimes it wouldn’t. Plz help 

[Dean2]

On 2/15/2024 at 9:02 PM, Mxjulian165 said:

I also came across a problem. I ran my 1990 Lexus LS 400 to empty and ever since I’ve been having problems with bogging and loss of power also when I start it up it almost sounds as if it’s cammed sometimes it run good sometimes it wouldn’t. Plz help 

Change your fuel filter and throw in a can of injectors cleaner like seafoam. Running the tank dry sucks all the crud off the bottom into the filter and fuel system. The bogging and loss of power is very likely a lack of fuel flow.

http://www.lexls.com/tutorials/EFI/fuelfilter.html