Sc400Jimmy

Hi guys,

I recently had a chain of problems with my 92 SC400 that were resolved. The ignition coils, spark plugs, spark plug cables, distributor rotors, ECU, MAF, and catalytic converter all were replaced and the car finally began working ok (not sure which of them resolved the issue). The problem was with the car dumping too much fuel and the car riding on only half the cylinders.

Now the car is working great, but after a while of driving, I notice that the car has a very foul smell of what seems to be fuel. It smells like it did before when I had the huge problem that lead me to replace all of those parts but this time the car is running, no rough idle, and the cats are nor glowing hot (thankfully)

Does anyone have any idea what this could be?

SC400slide

iTrader: (11)

That would be an exhaust leak, upstream most likely. You're smelling the unburned raw fuel and air coming out of a crack or seperation in the exhaust. Do you hear any hissing as well at idle?

Sc400Jimmy

Hi, sorry for the late reply to this thread. I'm new to this forum and didn't have the notifications turned on.

While I'm at idle, don't hear any hissing sounds. But then again, it's loud and I'm not able to really hear much.

I took the car in today because the last time I took it, the muffler was never screwed on tight. So they did that for me but I sti) hear it vibrating at times. The car smells like fuel very badly, it usually doesn't happen when I first drive the car. It's usually after a few minutes of driving that I smell it.

I've turned the AC on, off, but he car still smells very badly. Does it seem related to the muffler being loose?

rexst

If you are smelling a lot of raw unburnt fuel and notice your fuel consumption increase dramatically while the power is not quite what you remember it to be, your problem may be with your ECU. Nothing in the hardware is going to correct it unless you address the ECU itself. Our SC's from year 1992-1997 have a well documented problem of the capacitors in the ECU leaking over time. When the capacitors start to leak it messes up the signal sent to the injectors and sometimes the injectors stay wide open. I know this only because I have gone through it myself. You may want to do a search on this forum by typing SC400, ecu, capacitor, and I think you will see a few threads related to this. You might want to check it out. By the way, there are companies listed in those threads that can repair the capacitors so you don't have to buy a new ecu from lexus (who will give you a remanufactured one anyway, due to the age of our cars). Just as a test, why don't you try to source out an identical ecu that you can borrow (one that you know is from a properly working vehicle) and see if it makes a difference. I have a feeling that it will. Good luck.

Sc400Jimmy

Hi Rexst.

Thanks for your reply. However, the ECU had already been replaced as mentioned in the initial post. Do you have any other ideas on what it could be? I'm going to have it tested today to see if it's a EVAP related problem, but I have a feeling it could be an exhaust leak. The reason I think it may not be an exhaust leak though is because the smell only comes after a while of driving, say 30 minutes in.

Any suggestions would be great. Thank you!

SC400slide

iTrader: (11)

https://www.clublexus.com/forums/mai...-95-sc400.html

Sc400Jimmy

Thanks for the link SC400Slide. I *think* we fixed the problem. You were right, there were very small holes in the exhaust, upstream, that we would've never really been able to spot if we didn't take a close look while the car was lifted. I haven't had the smell come back since so I'm crossing my fingers!

Shrugy

iTrader: (12)

I've got the same issue now where my car runs on half the cylinders, lets hope I can fix this problem.

Mind if I ask what you paid to get all those parts replaced?

Sc400Jimmy

Hey Shrugy,

I just went through a whole lot of problems related to what you're talking about. I had another thread open about it (Can't find it now).

They ended up replacing the catalytic converters and the distributor rotors/caps (I believe that's the name) were completely destroyed, but that didn't fully solve the problem unfortunately. It only solved it temporarily, and on the way home, the exact thing happened again. Rough idle, the smell, running in limp mode and half the cylinders.

What the mechanics believe did the trick was the replacement of the ignition coil, the passenger side one (which breaks down rarely from what I've heard). The ground cable wasn't doing anything when they put it up to a monitor. Now the strange this is, they had already replaced that ignition coil so here it was again not giving anything out of the ground cable.

In the end, what they think may have caused the problem with the ignition coil itself was a small little fuse in the fuse box, I forgot which one it was. They were never really ever able to tell me exactly what caused the mayhem, but those were the things we went through and it worked and hasn't given me problems since. All they did with the fuse was clean it. It wasnt burned out eithe which is what was confusing; it just needed to be cleaned out and put back in.

I'm sorry I am not able to give you a more definitive answer, I feel your pain, but this is what we did to try to resolve the problem. If you can find my other thread on this issue, it will break everything down as I was actually going through it and will give you an idea of what we did. I ended up paying about $1600 total, plus the purchase of parts that I ended up not needing (ECU, MAF).

Please keep me updated, I would love to hear what you do to get your issue resolved. This guy SC400Slide helped me alot along the way, you may want to talk to him too