PjLex

I have a 98 Lexus ls400 with 220,000 mileage. Normally runs fine. and gets regular gas mileage. Lately I have had it die on me driving into work. I has happen twice or three times over the last month or month and a half. On all times it was a cold day around 30 degrees or less. I drive to work on the highway and get off on the exit ramp. I stop and then the car dies. This is after a good twenty minute drive on the highway. I have noticed that the warm up idle on the car can be a bit rough at times lately, like the last three months. Recently i have run two tank fulls with "techron" additive. and I normally get top tier gas like from shell stations. This is the first time I have ever had any problems with the idle or whatever it is.
Any advice would be helpful. Thanks!!!!

PureDrifter

iTrader: (10)

clean the throttle body and idle ports.

donteatbug

Also check the Air intake tube and vacuum lines for cracks. Any extra air introduced into the system after the MAF sensor can cause the car to stall and run rough.

Yamae

Are you sure?

PureDrifter

iTrader: (10)

pirate air can definitely cause rough running but it usually isn't temperature specific.

Try unplugging the vacuum tube from your brake booster and seeing how well it runs

PjLex

What are the idle ports?

PjLex

I just finished cleaning the MAF sensor and the throttle body. After a test drive, the idle is much better and very smooth. Before after warming up it would rough idle at around 3 or 4 rpm. Now it is a smooth idle at around 7 to 9 rpm. Out of curiosity, does anyone know what the warm up idle is ideally set to?
So I am pretty sure that my problem is fixed. Thanks for much for all the advice everyone!!

PureDrifter

iTrader: (10)

the idle ports are under a metal plate on the top of the throttle body (for '98-00 cars). just unscrew the plate and clean the ports out.

timmy0tool

iTrader: (7)

where are they on older cars?

PjLex

Just finished up cleaning the idle ports. I don't know for sure that's what they were but fairly sure by the descriptions others have given me. There was some build up in the ports, I would say half of them were clogged up with black stuff. Cleaned it all up and also the tunnels on each side. I'll drive it later and see if it helps any.
Thanks for all the advice!!! Best forum ever!!