alanluck

Someone feel free to call me crazy but this books4cars.com site shows manuals for 1990 LS400's and 1990 SC400's which weren't even produced for 2 more years. 1992 is the first year of either of these models, right?

I had a similar thing on my 92SC400. Then my timing belt broke while I was driving. After the timing belt was replaced, I stopped having this issue. Not sure if you want to peek under the timing belt shroud to see if anything is going bad. In my case, my belt tensioner was frozen, and the belt was basically rubbing against a frozen belt tensioner pulley until the belt overheated and snapped. This is something that was on my list, as no maintenance record is available for this vehicle. However, after buying it 2 weeks ago I immediately drove almost 2000 miles in a week going from Kansas City to Austin and back so I would hope if my situation was like yours it would have broken during the trip - I drove over 100mph from Dallas to just south of Oklahoma City and it ran great. No change though now that I'm back, runs just like it did. I'm going to look into this stuck butterfly valve scenario and see if I can check that without going to a mechanic. Thanks for the info! I found the original owner! He changed the timing belt at 96k so no worries there, and experienced the same low end hesitation I do. He never had his TRAC light come on solid though, so I am still looking for the source of this. I think next time it happens I'll drive straight to the Lexus dealership and see if they'll look at it. Aren't these vehicles OPD-II, so I can get a scan tool at the parts store and just hook it up and see what they would see?

Disconnect the battery for 90 seconds, it will reset the ECU. I might even err on the side of caution and leave it disconnected for five minutes.

One thing noone has mentioned is that you CAN use too much of this stuff and if you do, your engine is toast. As in locked up and ruined. I'm speaking of course in terms of letting the running engine suck it up through the vacuum hose attached to the valve cover (I never can remember whether this is PCV, EGR, or if the terms are interchangable since they both appear to do the same thing to me). Follow the directions precisely. Call a Lexus dealership if you want assurance of this, they'll tell you the same thing as will most mechanics. Half a pint at most!!!!

I had a similar thing on my 92SC400. Then my timing belt broke while I was driving. After the timing belt was replaced, I stopped having this issue. Not sure if you want to peek under the timing belt shroud to see if anything is going bad. In my case, my belt tensioner was frozen, and the belt was basically rubbing against a frozen belt tensioner pulley until the belt overheated and snapped. This is something that was on my list, as no maintenance record is available for this vehicle. However, after buying it 2 weeks ago I immediately drove almost 2000 miles in a week going from Kansas City to Austin and back so I would hope if my situation was like yours it would have broken during the trip - I drove over 100mph from Dallas to just south of Oklahoma City and it ran great. No change though now that I'm back, runs just like it did. I'm going to look into this stuck butterfly valve scenario and see if I can check that without going to a mechanic. Thanks for the info!

I'll look into it, thanks!

..problem is, slight hesitation when you give very light gas. Barely touch the accelerator and it jumps then lets off, then jumps again. Put your foot in it from the get-go and it runs like a bat out of hell. Lexus dealership drove around with a diag tool on it and everything was fine. Others are suggesting seafoam to burn off carbon deposits. Anyone else think this is a good idea?