piperscamp

Hello Everyone! Well, I finally got my '95 SC400 fixed. I Googled for a good Lexus mechanic and found one about an hour from my house. It was a long drive, but it proved to be worth it. When he did the check for my "check engine" light, he found several items. The first real problem is that my car (manufactured in September 1994) has the older computer check and only gives codes on general conditions. The codes showed an RPM problem, but that could be interpreted different ways by different mechanics. I was told it could be caused by several different things. Fortunately this mechanic diagnosed the problem correctly as one problem. It seems that I had a bad timing belt tensioner. This allowed the timing belt to slip and this messed up the idle as well as cruising. It didn't slip much, just a couple of teeth. Anyway, the labor is much more than the part (but a lot less than what a Lexus dealer would have charged). I think the tensioner is only about $50, but you have a take a lot of things off to get to it. So, a few hundred dollars later and my SC400 is happy again. My only advice to all is, if you have the timing belt replaced, replace the tensioner, as well. It's a very small additional charge. Thank you all and happy driving! Phil

Well, I opened up the IACV and it was very clean. I cleaned it anyway with high quality electrical cleaner (fast drying, no residue) and no help. I'm about done trying to fix this thing myself. I'm planning on taking it to the dealer and having them check it out. I'm not taking it back to my regular mechanic (Premier Auto Service) because they basically gave up after they replaced the crank position sensor. On a separate note, my catalytic converter was destroyed by what, THEY say, is a fuel problem. The converter was making noise like it was broken inside. They (Meineke muffler) is saying my warranty is void because of driving with the check engine light on. Anyway, my next step in a dealer diagnostic. They I'll have to decide if I want to spend the several thousand dollars I know they will want to fix it!!! Thank you all for all your help. If youall are interested, I'll let you know whether I keep it and fix it or sell it for parts!! :-( Take care, Phil Lewis

Thank you all for the advice on my problem. I was hoping I wasn't the only one with this problem. So, far, I've had the ECU rebuilt by a nice company on Ebay that offers a lifetime guarantee. http://www.autoecu.com For only $249, I sent them my ECU and they rebuilt it, returning it to me in only a couple of days (from the time I sent it to them in Tennessee, until I got it back was about a week). Unfortunately, that did not the fix the problem. They said they'd be happy to check it out again, but I don't think the ECU is the problem. I bought a used MAF on Ebay, but I still have the same problem. Same thing that you mentioned. I might try that again, but I think I'll check out the IACV Idle Air Control Valve that was discussed. At least that is a low cost solution. I'm thinking about taking it to the our local Lexus dealer for another diagnostic. There will be a charge, but at least they can tell me what the codes are saying that might be causing the check engine light. I had my non-Lexus mechanic check it out and he had a laundry list of codes including cam sensors. I'm hoping the Dealer will be better. I'm also wondering about the O2 sensors that were mentioned. Unfortunately, at my age and my bad back, I really can't crawl under the car and do that kind of work myself. So, O2 sensor replacement (all 4) could run over $1000. So, tomorrow, I think I'll check out the IACV and see what I can find. I can work under the hood with no physical problems. Thanks to everyone for their help. I'll let you know what happens. Take care, Phil Lewis

Thanks for your help. I'll check out getting a replacement oxygen sensor on Ebay. It has to much less expensive than an ECU. I'll search for that service manual. You know, when I was a teenager, we would put in new points, a new condenser, check the vacuum advance, and we were good to go. Too many sensors on these new fangled cars!! ;-) Thanks again. Phil

Hello! I have a 1995 SC400. Just recently, I have a "check-engine" light and the engine is running a little rough idling. Also, the engine does not run smoothly when driving using very little gas. I'll explain: At about 45mph, on a level road, it takes very little gas to maintain this speed. The gas pedal is hardly pressed at all. But, since it needs just a little gas to maintain this speed, the engine starts to "balk" for lack of a better term. I can take my foot off the gas pedal and it smooths out. I can accelerate with no problem. But, if I try and maintain about 45mph, the car is very "jerky." Now for my own trouble shooting: I guessed that there might be a problem with the Mass Air Flow sensor. So I unplugged it. The car runs fine. No "jerkiness" or idling problem. So, I replaced the MAF, with a used one, and plugged it in. Same problem I had before. So, I guessed that maybe the ECU is not working properly. Well, a new ECU can be as much as $1500, but I found a place on Ebay that will rebuild my old one (with a lifetime guarantee) for only $249. So, I had it rebuilt and installed it today. Same problem I had before. So, I unplugged my MAF and it runs fine (except I still have the check engine light). Also, as an extra note, when I turn on the A/C or turn it off, the idle speed responds appropriately maintaining a steady 600rpm. Smooth, with the MAF unplugged, or "rough" with the MAF plugged in. So....... whatdy'a think? Should I just drive it with the MAF unplugged? I'm hoping someone out there has a better idea. Thanks in advance for anyone who can help.