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Sputtering Problems Ls400


droptestls400
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so i have a ls 400 1991...started sputtering as if im out of gas..but im not..i hear maybe the fueel filter..this i could change on my own...fuel pump, maybe too expensive this week..need to get it rolling quick..when it DOES keep started, it runs rough , and a weird sputtering cycle..any ideas? email me if so....thanks...cody southpaw@droptest.org

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Most of my problems with my 94LS have been electrical, not fuel related. I would definitely check the wiring to the plugs and especially the coils. Sputtering is such an undefined area that you can spend a bundle at a repair shop for a possibly minor problem. I've found that American cars do have fuel problems and the like, but Lexus built a gem that doesn't have many regular glitches other than power steering pumps and several other problems that are fully noted here on the forum. Seems fuel delivery is not one of them. Very best of luck....

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I have this problem periodically from time to time.....it seems like the engine is starving for fuel or air...you step on the gas pedal & no power....just sputters along like it wants to die out, but doesn't...it like sputters with a rough idle.....

Seems to happen when I have run the air conditioner & engine is very warm.....Dont get me wrong...I am not saying it is related to the A/C......

I am able to get home most of the time......car was designed with a limp mode believe it or not....

Car sits overnight & runs fine the next day........this re-occuring problem may not happen for another three months or so but has come back enough to *BLEEP* me off...... I have not figured it out yet myself.... I know my plugs,wires, cap & rotor are good....

As people suggest, it could fuel filter or fuel pump related......I never have check the gas pressure when this has happened nor have I changed the fuel filter either....

Problem I have just learned to live with....242K miles on my car.....I am not dumping money for a new fuel pump.....filter would be cheap.....

All I can say is that it could be dangerous if it sputters along at an inapporpriate time.......railroad crossing, at lights, stop signs,,etc....

Be careful.....

Sorry, I have no definite answer for you....but I am in the same boat with you......you are not the only one with this problem....

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See if the fuel tank lines (that are supposed to suck fuel vapors from the tank into the carbon canister) are actually sucking in raw fuel to the canister.

This will make it sputter and choke.. changing the fuel filter would be a keen idea.

Maybe do the full serice of Seafoam (booster,oil,tank)

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See if the fuel tank lines (that are supposed to suck fuel vapors from the tank into the carbon canister) are actually sucking in raw fuel to the canister.

This will make it sputter and choke.. changing the fuel filter would be a keen idea.

Maybe do the full serice of Seafoam (booster,oil,tank)

How would you check to see if the fuel tank line are sucking fuel or vapors into the canister?

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  • 1 month later...

My 1996 LS400 has also started to constantly sputter.

Idle is very low and unsteady, and acceleration is accompanied by sputtering. If I take let off the gas pedal while accelerating, sputtering seems to dissipate for those few seconds until I need to push on the gas pedal again.

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Before buying anything part related, I would buy a can of Seafoam and run it through the gas. You very well might have water in the tank, causing it to miss. Springtime is a notorious time of year for condensation to build up over night on the inside of gas tanks, especially tanks that aren't full. It's worth $5 to see if that works.

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Here is a real cheap way to check what could be the problem. Go out and start the car on a damp humd night. Open the hood and look for the fireworks. You may hear a ticking sound accompanied by sparks jumping off the wires. They carry high voltage which moisture even in a trace amount attaches to the dirt on the wires and votage is lost. To fix it on a temporary basis, spray some WD-40 over the plug wires and distributor area. Maybe, just maybe...

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I have this problem periodically from time to time.....it seems like the engine is starving for fuel or air...you step on the gas pedal & no power....just sputters along like it wants to die out, but doesn't...it like sputters with a rough idle.....

Seems to happen when I have run the air conditioner & engine is very warm.....Dont get me wrong...I am not saying it is related to the A/C......

As people suggest, it could fuel filter or fuel pump related......I never have check the gas pressure when this has happened nor have I changed the fuel filter either....

Problem I have just learned to live with....242K miles on my car.....I am not dumping money for a new fuel pump.....filter would be cheap.....

I would suspect the fuel pump. Pumps that are weak or on their way out usually drop in performance when heated up. You might even be able to hear the pump working harder when warmed up. You could also check the main efi relay for corroded or loose terminals. Also check the resistance readings on the relay to be sure they're within spec. Other than electrical (which you say is ok) and fuel, there is the possibility of an intake leak which would give you a rough idle. The description you give that the problem seems to happen once the engine warms up suggests you could also check the coolant temp sensor.

You haven't mentioned the cel coming on, so I would check that the bulb is working when you first turn on the ignition to start the car. You might be getting codes without knowing it.

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Still sputtering constantly if I try to drive the car; sputtering never change or disappears whether morning or night, or 100F or 55F outside.

Since the CheckEngine light was intially blinking and is now steady, makes sense for me to go to AutoZone. etc to get the codes read.

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  • 2 weeks later...

Had the same problem on my 92 LS400. I read on a forum that it may be the Idle Air Controller. I messed with that and there was no change. Further reading said it may be a faulty Engine computer. I saw one on eBay and bought it for $95. Replaced it myself one weekend. Nothing changed.

The car sat outside for 2 months. Every once in a while I would go out and crank it up. It would start right up and then slowly die. If I tried to accelerate it woudl sputter and then eventually die. I finally had enough. So I called a tow truck and took it to a trusted auto repair shop.

I got a call today and they say it's the fuel pump. However, they want almost $600 to repair it. Now, that sounds a bit high as I see LS400 pumps for sale on eBay for less than $100. How much labor is involved? I'm going to do some poking around and see what I can find out. Meanwhile, has anyone gotten a fuel pump replaced? How much do you think it should cost?

Song

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If you can change the ECM, you can change your fuel pump. The hardest part is removing the back seat. It's bolted down by the seat belts. You ave to feel with your fingers between the bottom and upright sections to find them. And from the trunk pull down the panel opposite the upright section of the back seat to disconnect the wires.

Once the back seat is out there is a round panel with around 10 bolts.. Remove them to pull the fuel pump out. If you can get one there is a gasket for the round panel and a very fine mesh screen on the intake of the fuel pump that should be replaced if your are going through all of this.

You could have your fuel pressure checked, but this would probably cost as much as the fuel pump if you can get one for 100.00.

There is a website that maybe someone here on the forum can recall the name. Where for around $10.00 you can down load sections of the lexus factory repair manual.

Good luck

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If you can change the ECM, you can change your fuel pump. The hardest part is removing the back seat. It's bolted down by the seat belts. You ave to feel with your fingers between the bottom and upright sections to find them. And from the trunk pull down the panel opposite the upright section of the back seat to disconnect the wires.

Once the back seat is out there is a round panel with around 10 bolts.. Remove them to pull the fuel pump out. If you can get one there is a gasket for the round panel and a very fine mesh screen on the intake of the fuel pump that should be replaced if your are going through all of this.

You could have your fuel pressure checked, but this would probably cost as much as the fuel pump if you can get one for 100.00.

There is a website that maybe someone here on the forum can recall the name. Where for around $10.00 you can down load sections of the lexus factory repair manual.

Good luck

The service manual website is techinfo.toyota.com.

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Have you tried the Seafoam, or Heet, or STP Fuel Cleaner, or anything that is made to address water in the tank yet?

Man, you're about to spend hours chasing something that could be as simple as water in the tank, which is very common, especially at those miles! Again, before I would start taking anything apart, I would simply buy a $5 bottle of fuel conditioner, put it in your tank, fill it up about 3/4, and drive to see if it does anything to improve it. If it does, then there you go...buy another to make sure, and hit the road. If that's not it, then I'd start looking at the fuel filter first. Work from the cheapest part up until you fix it.

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Hey

This may seem arbitrary, but I may have an answer for you.

This same type of problem happened to me about a year ago. This smooth world class car started balking, cutting out, lurching, and seemed ready for the junk yard. It happened all of a sudden. No warning.

I thought the engine was toast.

Now it's smooth as silk w/ 255,000 miles on it.

Open the trunk. On the left side you will see a wire harness on the left hinge. After repeated openings and closings the wires inside that harness become fatigued and frayed. Then they start shorting out. Then your ECU starts getting bad input. Then your air/ fuel ratio goes to hell, then you have intermittant spark. Then sputtering, stalling, and everything you describe. This is a design flaw and lexus knows it.

In short ( :D ), if this describes your problem, then strip down the harness, untwist all the wires, re-connect, then re-tape with duct tape.

Make sure to leave off the bracket that ensures tension on the harness. Just let it swing free and loose.

In my case, problem solved, and no spending thousands of dollars in diagnostics, parts, and tech snafus.

I am 95% sure this is the answer. Best of all, it's free!

Good luck...

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  • 1 year later...

Hey

This may seem arbitrary, but I may have an answer for you.

This same type of problem happened to me about a year ago. This smooth world class car started balking, cutting out, lurching, and seemed ready for the junk yard. It happened all of a sudden. No warning.

I thought the engine was toast.

Now it's smooth as silk w/ 255,000 miles on it.

Open the trunk. On the left side you will see a wire harness on the left hinge. After repeated openings and closings the wires inside that harness become fatigued and frayed. Then they start shorting out. Then your ECU starts getting bad input. Then your air/ fuel ratio goes to hell, then you have intermittant spark. Then sputtering, stalling, and everything you describe. This is a design flaw and lexus knows it.

In short ( :D ), if this describes your problem, then strip down the harness, untwist all the wires, re-connect, then re-tape with duct tape.

Make sure to leave off the bracket that ensures tension on the harness. Just let it swing free and loose.

In my case, problem solved, and no spending thousands of dollars in diagnostics, parts, and tech snafus.

I am 95% sure this is the answer. Best of all, it's free!

Good luck...

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Where is The harness exactly at? is it close to the speaker relay? and what is it called? im having the same problem with a 93 ls400. car will start but will not drive if gas pedal is depressed. it will gradually move if left in drive. but once gas pedal depressed, it will just die out. i checked the air/flow meter, idle controller, throttle body, changed fuel filter, air filter, spark plugs, engine sounds good once started, but there is definetely a air/fuel ratio problem. please get back at me as soon as possible. thank you so much for your help!

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  • 3 months later...

burhan24, any solution or update on your situation?

Where is The harness exactly at? is it close to the speaker relay? and what is it called? im having the same problem with a 93 ls400. car will start but will not drive if gas pedal is depressed. it will gradually move if left in drive. but once gas pedal depressed, it will just die out. i checked the air/flow meter, idle controller, throttle body, changed fuel filter, air filter, spark plugs, engine sounds good once started, but there is definetely a air/fuel ratio problem. please get back at me as soon as possible. thank you so much for your help!

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  • 6 years later...

I've got a 1995 ls400 with 78,000 original miles. It began stalling out after exiting the highway after 11/2 - 2 hrs of driving. This is within the last four months.  I checked these posts and it seems that the ECM is the problem. I also have the 40 mph rough engine ride. Is there any suggestion for where to buy ECM. Dealer cost is whopping $2200 plus tax. Other than that car is just a beauty.;Help!!!!!!1

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