SPLiFFY

Hey Everyone,

I just want to say I love the forum and it truly has helped me so much. I just got Lexi (95 SC300) because she's been passed down within the family. My dad bought her used in 2006, and just the other day she hit 114k miles. She's in excellent condition but I could use ANYONE'S help on this problem.

Okay..

So I've read that these models of cars have many problems stalling, but I've taken this car to everyone and no one really KNOWS what's wrong. I even tried taking it to Autozone and other stores and no one even has the scanner for the car. I could take it to a Lexus dealership, but this one mechanic said it could be the computer. He said that if the car is hooked up to the scanner, the computer won't tell you that it's bad.

Anyways, with the original ECM in, the problem would just stop in the middle of the road. It would drive just fine, and the car would shut off out of no where. My dad's friend put in another ECM and the problem with that computer is that it's stuck in 3rd gear. I mean I drive it around locally, but it stalls too. Like, when I'm at a stop sign I get so nervous because I have to like inch to the stop line so it won't shut off on me. I don't know how to describe it. I mean like when I'm sitting at the stop light, the car gets silent and you don't hear the engine running anymore.. that's what I mean. And I mean some days it drives perfectly fine. I just don't trust her because I've pushed her with my dad through so many intersections :\ LOL.

Bottom line, she has a terrible idle. And I mean sometimes when I'm trying to make a left, she like studders and I don't think I can even turn, but eventually she pulls it together and she's okay again. My dad himself is a mechanic, and doesn't have experience with Lexus. He narrowed it down to the ECM, the relay, or the fuel pump.

I know many of you have this car, and have experience, and I pray that you can help me solve this issue. I don't want to buy an ECM and that not be the problem. I'm actually looking for an ECM online right now and it's damn near impossible.. or too expensive

Another question: The part # is 89661-24350. When buying a new ECM, does it matter if the part #s match up.. even if it says that it fits? Or do I even need an ECM?

I appreciate you all for reading this. Thank you..

dwebb99

iTrader: (17)

Have you ever changed the fuel filter? Next, have you ever changed out your Fuel Pressure ECU? (just do a search on this, it's a very easy and cheap DIY). Next, I would TRIPLE check EVERY electrical connecter in your engine bay and find a Autozone, Pepboys,O'Riley's, or indie shop that can perform a very simple Engine Code check for free...your problem should be pretty simple to troubleshoot and track down.

SPLiFFY

The fuel filter wasn't changed, at least I don't think. My mother doesn't live with me, and she had this car so I don't know what was done to it before I got it. Everyone is so stuck on it being the ECM, and I really don't think so. But what do I know -_-

Like what are the chances that both ECMs that were put into the car is causing it to have a terrible idle? But when I try to tell my dad that he says he thinks it's something like the messages are being sent to the computer or whatever.

I'll ask about the fuel filter though, and I'll ask for my dad to check out the electrical connectors. Is there any other precautions I should take before I jump to buying the ECM?

Thanks.

Carfreak70

iTrader: (16)

I am with dwebb on replacing the Fuel Filter.

Out of curiosity was the MAF ever cleaned with MAF cleaner? If so, that is your problem. If anything has touched that MAF that is a chemical, it basically ruines it. I would also check plugs, rotor cap, and button. Those are ignition items, that if have not been replaced in a while very well could cause stalling problems.

SPLiFFY

Well, we did take out the original MAF at first and replaced it with a used one that we bought on Ebay. That surely didn't fix the problem. We also changed the ignition modules numerous times and still stalled. I will ask him to check it. Thank you very much. I will surely ask about replacing the fuel filter.

Also, my dad keeps on ignoring everything I say and he's telling me to just buy the computer. Thing is, I called to one place and I asked if the ECM part #s had to match, and they said it does because it's a federal emission car or something like that. I don't know what they said. But in other words, they said the part #s on the ECM have to be the same or the car won't "react."

The ECM that's on the car, that probably isn't the same part #, do you all think that could be a problem? My dad keeps forcing me to buy the ECM and I really don't think that's it. :[

dwebb99

iTrader: (17)

Sorry, I meant to say check your "Fuel Pump ECU". It is a cigarette pack sized control module that controls your fuel pressure. This little unit is prone to failure and intermittant operation on SC's and you need to do a search on this forum and read up on it. It is very easy to replace and costs about $30 used. Same goes for the fuel filter. Also you need to check your rubber intake boots for holes/cracks from your MAF to your throttle body AND ALL of your vacuum lines!. Rough idle (assuming you have a good tune-up) is often caused by vacuum leaks .My best advice since you do not know the maintenance history nor much about this car is to invest in a factory service manual and/or a Haynes manual and review/read the troubleshooting sections and start learning how this fine car operates. It appears you and your father are just ASSUMING so called "fixes" without CONFIRMING what is at fault. Throwing big money on "suspect" parts does not guarantee a fix. Close to a ga-billion of these engines have been produced and they are very well engineered motors and are really quite simple to work on and will run for many 100,000 thousands of miles if properly maintained.While anything is possible, faulty MAF and ECM (or ECU's) on the SC's are rare and not a common weak point. If you don't have the skills or talents to work on this car then you need to find a good independent Toyota shop to find your problem. Dimes to donuts it's a very obvious and simple issue. Spark, fuel, compression.....and you have " lift off". So....is it fuel or is it electrical (or both) and/or vacuum leaks, that is causing the rough idle and/or the stalling?....time to troubleshoot......good luck and keep us posted on the culprit.

TechGreek

iTrader: (4)

I can't say whether or not you need an ECM without seeing it (and the capacitors inside) but I will tell you, YES - the part numbers need to align if it's going to be used for more than testing.

The 91-93 ECU will work with the 95, however, it has a slight hesitation upon acceleration.

Tabaka

iTrader: (8)

I'm definitely not an expert bud, but I feel your pain. My advice is to pay Lexus $120 to inspect everything and give you a proper diagnosis. My friend gave me some good advice last night and had a funny quote, "it's the best $120 you'll ever spend". And it's pretty much true. Best of luck with whatever you decide, but I've learned that mom and pop mechanics just can't diagnose these vehicles properly.

Because your car is a '95, no one has OBD1 Toyota scanners anymore. You will need to read the DIY terminal jump to pull your codes properly.

OG Dada

iTrader: (10)

This is a pretty common problem, let me link some thing that helped me a lot if you're on a budget like me... The thing about these cars is it's the first cars to get electronic parts introduced to them, so it's like we bought test products when it comes from that aspect... But bear in mind that this model was available for 10 years with little to no changes... These are really reliable but since it's the firsts with electronic parts like I said, there are a lot of parts that are defective since they come from a production line... I've yet to hear people changing the same parts over and over again wether used or brand new on these cars... Some would say they did, so too bad for them... Anyways;

I'd also suggest for you to check all electrical groundings in the engine bay, clean TPS, and follow this link...

https://www.clublexus.com/forums/sc-...on-issues.html

If you use dirt cheap fuel on these cars, the fuel filter would go bad quick, so might as well replace it... You can buy it for less than $90 brand new from Lexus Sewell with our Club Lexus membership discount...

Good luck!

SPLiFFY

Wow,

Thank you all so much for the input regarding this issue. When my dad gets in tonight, I will read all of this over with him. As far doing all of the simple diagnostics, I will make sure all of these things get handled accordingly. I am planning to take the car to a shop for all of these checks, but getting there is also a problem. It's 5 minutes away but takes like 15 mins to get there with Lexi lol.

Right now, Lexi has a different computer in her, and the part number doesn't match with her original. I didn't know about the 91-93 thing, so thank you for telling me... I guess that's why she studders so much when I drive her. As far as everything else, my dad still won't give up the idea of it being the ECM, so he is sending to be rebuilt tomorrow and shipped back.

Once the ECM is replaced, then all these checks all of you told me about will be done too. I will be sure to keep you all posted as to what happens when the original ECM comes back. I don't want to do all these checks until the original ECM comes back, because it would be a waste with this temporary ECM in her.

Anyways, I will read this to my dad and I will keep you all posted. Thank you for reading and giving your input.

Kira X

iTrader: (24)

Try the 12v fuel mod when you get the chance. It might solve your SC's problem.

Here is a link on how to do it: https://www.clublexus.com/forums/per...tures-faq.html