ls400beave

Hey thought I would ask for some advice. Recently my car started and automatically died. When I went to restart the car it was turning over very quick like the engine was not engaging just spinning (made a different turn over noise). My neighbor who is a mechanic automatically thought it was the timing belt. We took front part off and belt was fine (changed 50,000 miles ago). Put it back together and battery was almost dead. We charged it and then started cranking, giving it full gas. It finally started (smoked like crazy and then ran fine).. I believe the battery was the issue (this was two weeks ago). However, the idle seems low (kind of always been low since I purchased but seems even lower now). It is around 300k when at a stop light and around 500 in park. It has a little vibration at stop in gear like if it goes any lower might stall. I did notice the it was pretty dirty by the intake circle (when I took off the air black air intake cover). Had some gunk circled around the throttle thing that opens and closes.. I was thinking about cleaning that out. I was going to get some safe carb spray and a tooth brush. My brother told me to use seafoam but I am a bit warry about that. Let me know what you suggest. Many thanks for advice. BY the way the car has 230,000 miles on it and it has a old battery.

ls400beave

Just posted a pic to my profile

ls400beave

The car is my baby and I want her to run ohh so well. I am going to get a new battery when I get some safe carb cleaner but I do not think the new battery will help the idle any. Let me know your thoughts..

ls400beave

So I am going to clean my throttle body. Does anyone have a link that would show good details on how to that? I found one but it is for the 1st generation. I need one for the 98 to 00. See link
http://www.lexls.com/tutorials/EFI/throttlebody.html

PureDrifter

iTrader: (10)

this one is pretty much the same. the only thing i would do different is pull the throttle body off the car to clean it (but that requires draining a little coolant or making a big mess lol)

https://www.clublexus.com/forums/mai...and-gs430.html

j three

About two months ago my car stalled and it just turned out to be dirty oil. I was at about 6k miles on the oil and I knew it needed changing. I changed the oil the next day and back to normal. I was scared though I have to admit.

ls400beave

Hey everyone. So I purchased some throttle body cleaner and cleaned the throttle body. It was like tar build up in the ring. I left the throttle body attached to the engine and sprayed a little bit at a time using a rag and tooth brush. I cleaned it very good. Now when I refired the car the rpms were at 1800 in park and would drop to 1100 in gear. So I drove around 5 miles and the rpms have come down a bit. Its now around 1100 in park and 800 in gear. Which concerns me a bit. I was hoping to have a bit higher idle not this high. Now I did read a couple of threads where people had the same issue and it took around 20 miles for the idle to come down to normal. The car has more pep on it now let me tell you. Let me know if anyone has had the same issues. I still need to drive it some more and figure it out. Any thoughts would be great

andyman32

Just some general advice, an idle that high would usually be either unmetered air in the intake manifold or a bad throttle position sensor (rheostat).

In the case of a bad TPS, it would be sending false signals to the ECU about the throttle position. You'd probably be noticing some erratic behavior while pressing on the accelerator as well.

If it's an air leak, it may not necessarily be external. I don't know if this car has a throttle plate idle position set screw (to allow some minimal amount of air to bypass the throttle plate in the throttle body) or if it has an idle air valve, I can look when I get home. The idle air valve might go bad and can cause high idle, low idle, stalling, all because it fails to permit the correct amount of air to bypass the throttle plate when it's closed.

If idle air is controlled by a set screw, the junk in the throttle body may have been slowly choking off the bypassing air, but even in that case, unless some crud spilled in there suddenly, it's unlikely that you'd notice such a sudden change in idling behavior.

I'll look at my car this afternoon and figure out what's what on the TB.

If you disconnected the battery there's some possibility that you might need to go through a couple drive cycles for the ECU to "re-learn" the correct sensor settings. But this does not sound like a bad battery.

PureDrifter

iTrader: (10)

just drive the car, the ECU learns a fair bit so it'll compensate. you aren't that far off given spec since FSM asks for ~650RPM +/- 100RPM at idle in gear iirc.

ls400beave

Thanks guys for the advice... I will update you all soon. Wife drove my car today.

Michael88

I have intermittent no start situations that I am currently diagnosing. Not easy, even for the dealer. I have a new battery, clean throttle body, new alternator, and all were due for replacement and cleaning anyway. Still a rare no start. Does your intake hum on the driver's side after a no start? I suspect my accelerator position sensor (APS) needs calibrated after I tightened the throttle cable a bit due to 20 years of use. If I disconnect the battery and APS, then reconnect she fires up and drives. My idle seems low, too. After warm up it drops to about 500 rpm in Drive, yet a cold morning start in Park will start at 1200rpms then settle to about 900 rpm. I am also checking a recent replacement idle pulley. It may be bad, causing spiking voltages. This can mess with 5v supplied to the APS, I believe.