I am not a mechanic. I tuned up ( new plugs, plug wires, distributor cap and rotors ) my '92 sc400 ( with 137K miles on it ) when COVID kept me home from work for 5 weeks in April. On passenger side of V8 engine there were several hoses and the whole air filter intake unit I had to disconnect and then reconnect to get to cylinder head to replace plugs. 2 or 3 of the small hoses tore/frayed at their ends where they connect to the male metal parts of the engine when I took them off. I wrapped the ends with Gorilla tape and forced them back on over their connectors. Right after I finished tune up I took car out and it ran great on freeway at high speed and performed great during my 10 minute test drive. 3 days later I started the car again and it doesn't go faster than 25-30 miles an hour because transmission doesn't shift out of the low gears. If I keep it in park and rev the engine it sounds great and easily goes up to 3500-4000 RPM smoothly. Transmission fluid is good color and doesn't smell burnt and is at normal fluid level, I tested it with engine warm and cold. Does anyone know which ? intake or vacuum hose on passenger side of engine is involved with transmission. Can I go to Pep boys with hose sections and buy new same diameter rubber hoses and replace the hoses I tore? Or do I have to get special Lexus hoses from Japanese auto parts online retailers? Any suggestions? Thank you for reading this post.

 

did you recheck your steps on the tune up you did earlier this year? ensure everything was placed how it was before (e.i. rotors on correct way you took them off). I know it sounds dumb but it happens to all of us. Just a suggestion

 

Thank you for reading my post slackful.

I did the tune up really slowly because I had a lot of time on my hands due to covid. I made sure the caps and rotors went on the exact same way I took them off and the plugs were all in correctly and all the plug wires went to where they were supposed to go. I took cell phone pix and videos after each step to make sure I didn't mess up. When I finished I took a 10 minute freeway test drive and it ran flawlessly, so I don't think I did something wrong during the tune up and it is hard to believe that the transmission would go 3 days after I did the tune up, though I guess it is possible. I think there is an intake problem with one or more of the hoses I forced back on that I tore the ends of when I took everything off on the passenger side of the engine to get to the plugs on that side.

 

Okay I would definitely check those off as a source first if thats your main concern. Another thing that happened to me, which makes sense for you, is that when putting everything back you may have left a cord out of its clip on harness and maybe a belt or pulley may have sliced or cut it. Drove well the first ten minutes while the belt or pulley may have eating at whatever is causing this. Happened to me with my cam sensor on the passenger side. There was exposure to the wire and cause shuddering after warmup and hesitation, even stalling at lights. Try those after. Hope this helps.

 

This is a quite common shift solenoid problem. They are easy to replace and you can do it right through the transmission pan in about 15 minutes.

 

Thank you for responding Slackful. I didn't think of that. I will definitely look into that, there were several clips that held the different hoses and some of the hoses attached below where I could see from the top of the engine looking down. I shined a flashlight and attached them to where it they went before I took them all off. I have had a bunch of other things I have had to do recently and I don't rely on the car as transportation, so I haven't had time to get back under the hood recently. Do you think if I took the different diameter hoses to Pep Boys they could sell me similar hoses to replace the bad hoses with? I guess I can go online and find them if they are available. Thanks again for your advice.

 

Thank you Curtis4661 for reading and responding. I will look for you tube videos on replacing shift solenoids. I need to put the car up on blocks to get to the transmission pan right? I have ramps for raising the car when I do oil changes on it and I know where the transmission pan is. I will check into it, thank you very much.