93ls400walt Posted November 5, 2007 Share Posted November 5, 2007 I have had a few post over the past year about my ls that ran fine, smooth idle no missing ect. You could floor the engine in park or neutral and it would hum. But when under slightly more than light acceleration in drive, espically with the A/C on, or one or more passengers, the rpm would drop around 4-500 rpm and the car would stop moving forward under power. Unless you let off the gas peddle then re-accelerated slower. Some others with this have replaced the ECM with good results reported. I was planning on sending mine off for repair for some time, but the money would be needed for something else, so I let it ride. I knew that I had some old vac hoses, loose fitting. mainly the ones connecting to the aluminum air intake chamber on top of the engine. So while at the Lexus dealer getting some maintance parts I saw that they had vac hose for sale. I bought $3.00 worth. When I got home I replaced two short vac hoses. Finished my maint. ( cooling system ) and went for a ride. The car had more power, but I was "afraid " to accelerate harder to check it out. But today I was out and the car was still running better than ever, and found myself on an open deserted road. So I just pressed the peddle fast half way and the car took off, no hesitation. So then I floored it, the trans. kicked down, and the car roared. I did this several times the rest of the way home with the same response. WOW, it felt great. one, to have the car back to better than before, since I had replaced coils,plugs, wires, caps ,rotors, fuel filters, seafoamed the heck out of it. Cleaned the TB and EGR many times. Changed the TPS. I am holding my breath though. I just can't believe it was this simple. Quote Link to comment Share on other sites More sharing options...
pishta Posted November 5, 2007 Share Posted November 5, 2007 I have had a few post over the past year about my ls that ran fine, smooth idle no missing ect. You could floor the engine in park or neutral and it would hum. But when under slightly more than light acceleration in drive, espically with the A/C on, or one or more passengers, the rpm would drop around 4-500 rpm and the car would stop moving forward under power. Unless you let off the gas peddle then re-accelerated slower. Some others with this have replaced the ECM with good results reported. I was planning on sending mine off for repair for some time, but the money would be needed for something else, so I let it ride. I knew that I had some old vac hoses, loose fitting. mainly the ones connecting to the aluminum air intake chamber on top of the engine. So while at the Lexus dealer getting some maintance parts I saw that they had vac hose for sale. I bought $3.00 worth. When I got home I replaced two short vac hoses. Finished my maint. ( cooling system ) and went for a ride. The car had more power, but I was "afraid " to accelerate harder to check it out. But today I was out and the car was still running better than ever, and found myself on an open deserted road. So I just pressed the peddle fast half way and the car took off, no hesitation. So then I floored it, the trans. kicked down, and the car roared. I did this several times the rest of the way home with the same response. WOW, it felt great. one, to have the car back to better than before, since I had replaced coils,plugs, wires, caps ,rotors, fuel filters, seafoamed the heck out of it. Cleaned the TB and EGR many times. Changed the TPS. I am holding my breath though. I just can't believe it was this simple. So, you are talking about the 3-4 small "S" routed hoses coming off the cast intake horn? Mine has done that twice off idle A/C on full after waiting in line. Ill look at mine. Quote Link to comment Share on other sites More sharing options...
93ls400walt Posted November 6, 2007 Author Share Posted November 6, 2007 one is directly on the front of the alum. intake very short & S shaped. By the IAC. The other also short & S shaped on the left side of the intake just behind the TPS. ( these hoses are the smallest diameter of any of the vac hoses that you can see. you do not have to remove anything to see them ) Of note. The ls is running much much better. But today with my wife in the car I did have recurrence of the prob. during a much more aggressive acceleration. But to a much less degree than before. Quote Link to comment Share on other sites More sharing options...
qha_vn Posted November 6, 2007 Share Posted November 6, 2007 great finding, could you post a pix of the hose you have replaced? that would surely help us not to replace the wrong ones Quote Link to comment Share on other sites More sharing options...
93ls400walt Posted November 7, 2007 Author Share Posted November 7, 2007 I'll try to post a pic. But you can easily replace any of your vac hoses for a few dollars. I am going to replace each and every on that I can find. Even if they are not loose they may have small cracks after all of these years and loosing vac. Quote Link to comment Share on other sites More sharing options...
ko90ls Posted November 7, 2007 Share Posted November 7, 2007 Be Advised that each year LS may have a different route. The car on Lexls is a 91 which has many different Hoses routed than my 90, but there should be a pic of the vacuum lines under the hood (next to the belt pic) Quote Link to comment Share on other sites More sharing options...
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