Dangerous Engine Issue

[Champak]

After doing 85mph+ for an extended period of time...30min+ or so, when slowing down to below 30mph or so....traffic or coming off the ramp, the engine light comes on and shuts down. You can imagine how dangerous that is on a highway with heavy traffic or coming off a steep turn ramp with practically no power brakes or steering power. I'm worried that at some point this is going to start happening without me doing the high speeds first. What could possibly be the problem?

[1990LS400]

It would help if you put the model year of your car either in a signature or the "Car model" field. I figured out from one of your past posts that your LS400 is a 1994.

First of all, it's not good to keep driving a car that dies unexpectedly. What's going to happen if the engine dies and you can't get out of someone's way?

Being a 1994, the problem could be related to a dying alternator -- typical on the 90-94 LS400 due to power steering fluid leaking on to the alternator. Or it could be a bad battery or battery connection. Or some other electrical connection that has become corroded over time.

Are their any stored diagnostic codes? Some people have reported that stores like Autozone can pull the codes.

[lexstar]

http://www.lexls.com/tutorials/intro/codereading.html

put it in N and start it.

dose it start right back up?

idle's at?

rev hold 3000rpm let off hot dose it die slow idle speed control valve (ISC) clean

dam thats alot of miles

[Leadfoot]

After doing 85mph+ for an extended period of time...30min+ or so, when slowing down to below 30mph or so....traffic or coming off the ramp, the engine light comes on and shuts down. What could possibly be the problem?

Depending on the model you have it may be related to the ECU. There was a series of ECU's on the 95-96 years that had idle problems if your aircon was OFF. The problem does not get worse, but it is still a danger/hassle. The car started right back up again and didn't play up right after did it? Try with the AC on and see if it happens again in the same situation.

For the full details refer the following thread;

http://us.lexusownersclub.com/forums/index...9&hl=stalls

[90LS400Lexus]

85+ mph for extended periods? :o Never can even try that here... they would have you behind bars so fast your head would spin, or you would pay a $800 fine. ;)

[Champak]

@lexstar, I don't understand anything you said.

@Leadfoot, When the car died, after the long run, when I tried to start it again, the engine would idle at 100-300 and then die out the first few times I tried to start it.

"Try with the AC on and see if it happens again in the same situation."

That should be fun...purposely run the car way beyond the speed limit to try and get the engine to shut off on me. Talk about troubleshooting...that should be fun; if I don't crash, "Sorry officer, I was trying to get my engine to shut off on me :)." But I guess you got to do what you got to do.

@1990LS400, Not relating directly to this problem, but a few days this winter here in NY, the temp was below 10 and those days the car either didn't start, or would start and idle at like 100 and then die out...if I revved it, it would die immediately. Would that be a problem with steering fluid leaking on the alternator?

Thanks

[Marklouis]

@lexstar, I don't understand anything you said.

@Leadfoot, When the car died, after the long run, when I tried to start it again, the engine would idle at 100-300 and then die out the first few times I tried to start it.

"Try with the AC on and see if it happens again in the same situation."

That should be fun...purposely run the car way beyond the speed limit to try and get the engine to shut off on me. Talk about troubleshooting...that should be fun; if I don't crash, "Sorry officer, I was trying to get my engine to shut off on me :)." But I guess you got to do what you got to do.

@1990LS400, Not relating directly to this problem, but a few days this winter here in NY, the temp was below 10 and those days the car either didn't start, or would start and idle at like 100 and then die out...if I revved it, it would die immediately. Would that be a problem with steering fluid leaking on the alternator?

Thanks

born and raised in New York are ya? i can tell <_<

fix that steering leak for sure-and that alternator has served well, replace it too. if that doesnt fix your issue, at least you know it eliminates that theory.

good luck!