bencho Posted January 6, 2009 Share Posted January 6, 2009 The topic says it all... Upon startup, the my 1990LS accelerates fine. But maybe 30 minutes of driving and the shifting goes to hell. I'll floor it and it revs to 2200 or 2400 and drop to 1400 or so. And I have no moving power whatsoever. If I get to a stoplight, I quickly turn off the ignition and restart the car. This works most of the time, but is impossible to do on the highway.. which is when we all need power to move. Quote Link to comment Share on other sites More sharing options...
VBdenny Posted January 7, 2009 Share Posted January 7, 2009 When you apply the brakes, does the Reverse light come on by any chance? Quote Link to comment Share on other sites More sharing options...
bencho Posted January 7, 2009 Author Share Posted January 7, 2009 Negative. Thought I rarely use those things you call "the brakes". My Car's all Go! :D Quote Link to comment Share on other sites More sharing options...
1990LS400 Posted January 7, 2009 Share Posted January 7, 2009 I think VBdenny was alluding to the common problem where wires at the left trunk hinge break and cause all sorts of transmission shifting problems. There are plenty of past threads about this problem. The fix is to remove the insulation from the wire bundle at the left trunk hinge and splice in small lengths of wire using either solder or wire connectors and insulating each wire so that no bare wire touches another one. If you have never checked the wires in the left trunk hinge, do it now. They always fail at some point on a gen 1 LS400. Quote Link to comment Share on other sites More sharing options...
eatingupblacktop Posted January 7, 2009 Share Posted January 7, 2009 How long have you had this prob? Any codes? I would check your alt's output. Sounds like it could be starting to fail. Quote Link to comment Share on other sites More sharing options...
bencho Posted January 7, 2009 Author Share Posted January 7, 2009 ARgh... I already replaced my alternator after I got stranded on a bridge once when it failed... Maybe 8 months ago!! I put in a new battery as well as I didn't know when the last time it was changed. I know of the PS fluid leak on the alternator but I just got an oil change and had the mechie look at it. He said there is no leak on over the alternator. However, the PS fluid IS LEAKING little pipes where the brakes are in the front wheels. That's not too bad as I can always get $5 bottles of PS Fluid. There were no loose wires when I looked but I never removed the insulation. And no, there are no codes popping up. Another thing is the gas mileage... 1990LS has 22 gallon tank, correct? I hit the halfway mark today and noticed that I only got 100 miles... 10 miles per gallon?! I already had the speed sensor inside the tranny replaced about a year ago. The only problems now are the shifting and the speedometer needle is broken. Quote Link to comment Share on other sites More sharing options...
eatingupblacktop Posted January 7, 2009 Share Posted January 7, 2009 I would check that speed sensor again. I still think your your volt regulator could be the prob. Quote Link to comment Share on other sites More sharing options...
90LS400Lexus Posted January 7, 2009 Share Posted January 7, 2009 1990LS has 22 gallon tank, correct? I hit the halfway mark today and noticed that I only got 100 miles... 10 miles per gallon?! Ew, yes, something definitely wrong. I filled up my 91 LS400 the other day and tonight I noticed that I have went 134 miles and its still a little over 3/4 tank. Quote Link to comment Share on other sites More sharing options...
bencho Posted January 7, 2009 Author Share Posted January 7, 2009 What/where is the volt regulator? How would I check that myself? Eatingupblacktop-- You suggested that it could be the speed sensor again... that brings this question to mind, my speedometer needle is 'broken'. Would a screwed up speed sensor send the needle past the zero mark into the negatives? Cause the needle registers at the lowest possible point when idle. When I'm at like 2000 rpm cruising, it chills at 20 mph. Increasing and decreasing speed moves it very slightly.. Max I've gotten it is to 30 mph. I'd take a venture and say that my actual speed is about 3 times what the needle actually registers. Does this mean the needle itself is broken or a trippy speed sensor? If the needle is broken it wouldn't move at all, right? Cause I'm looking for another dashboard and it'll cost several hundred. I don't want to replace it and find that its the damn speed sensor again. Because if it is the speed sensor... maybe It's registering 1/3 of my actual miles too? Quote Link to comment Share on other sites More sharing options...
eatingupblacktop Posted January 7, 2009 Share Posted January 7, 2009 What/where is the volt regulator? How would I check that myself?Eatingupblacktop-- You suggested that it could be the speed sensor again... that brings this question to mind, my speedometer needle is 'broken'. Would a screwed up speed sensor send the needle past the zero mark into the negatives? Cause the needle registers at the lowest possible point when idle. When I'm at like 2000 rpm cruising, it chills at 20 mph. Increasing and decreasing speed moves it very slightly.. Max I've gotten it is to 30 mph. I'd take a venture and say that my actual speed is about 3 times what the needle actually registers. Does this mean the needle itself is broken or a trippy speed sensor? If the needle is broken it wouldn't move at all, right? Cause I'm looking for another dashboard and it'll cost several hundred. I don't want to replace it and find that its the damn speed sensor again. Because if it is the speed sensor... maybe It's registering 1/3 of my actual miles too? Check the sensor and connection. The regulator is on the alt. Have it load tested. Quote Link to comment Share on other sites More sharing options...
don corleone Posted January 8, 2009 Share Posted January 8, 2009 your trans have two speed sensors and one speedometer sensor. these are very different. the speed sensor measures one thing and the speedometer sensor is kinda like a distributor on a honda. it has a gear which spins with the trans output shaft and registers the speed. it is possible that the speedometer sensor is messed up and not sending the correct information to the dash. also you can rebuilt the instrument cluster. check out clublexus.com on the LS section there is a sticky with information about rebuilding the dash. Quote Link to comment Share on other sites More sharing options...
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