LS 400 dying at idle

[Gipraw]

93 LS 400 .. 189k on the clock ..

runs fine down the road, but this morning .. started stalling at idle .. sputters and dies at a stop light, dies quicker at idle with a load on the engine, i.e. turning out of a parking space ..

temps look fine ..

I am heading home to take a look at it for the wife .. what specific should I be looking for with this motor ?

thanks ..

 

[Lextreme II]

If the car is not dying. How does it behave? Was your A/C on? Its possible its the idle speed valve.

 

[Gipraw]

the car drives fine .. no hesitation, no sluggishness .. but when it is just sitting at idle .. the rpm's slowly decay until it stalls. With the A/C on, it seems to hang on at about 500 rpm .. although it did stall on me turning around in the driveway, even with the A/C on.

From the searches I have done,. I gather cleaning the throttle body is a good place to start .. then I will do the normal tune up type stuff .. rotor, plugs, etc.

would the A/C running help if it is the idle speed valve?

 

[Lextreme II]

I think cleaning ISC will help.

 

[persevere]

My 1990 LS400 was doing the same thing...I discovered it does not like low voltage. The alternator was not working at low RPM. Replace alt and no more problem. Good luck

 

[jibbby]

Check the TPS (throttle position sensor)

 

[Gipraw]

My 1990 LS400 was doing the same thing...I discovered it does not like low voltage. The alternator was not working at low RPM. Replace alt and no more problem. Good luck

we seem to have a winner .. thanks..

after doing all the tune up stuff, I was still having issues .. since it is wifey's car, I don't drive it much .. but I took it for another spin, and noticed the power steering pump was noisy.. after looking harder, I noticed that the pump had leaked into the ALT. so I replaced the pump, and the ALT, and all seems to be well .. plus, I have a clean TB, new plugs, wire and cap .. fun stuff

thanks for the ideas and info ..