Low Idle on 2000 LS with 55K Miles
01-25-19, 08:33 AM
#1
Driver School Candidate
Thread Starter
Low Idle on 2000 LS with 55K Miles
Hi everyone. I purchased a 2000 LS400 with 55K miles on it a few weeks ago and it has a few minor issues I've trying to chase down. The car was well serviced at the dealership, but such low miles, it was mostly for oil changes. It hadn't had the timing belt changed, so I immediately had that and the water pump service done. The belt looked pretty new, but it was fraying at the edges. After reading up about the engine coolant temperature sensor in the big thread and noticing how my temp gauge wasn't very consistent, I decided to replace it. Sometimes the temp gauge needle was slightly below the second line, on second line or slight over the second line. I immediately saw some fuel economy gains and the temp gauge is consistently slight over the second line. This leave me with only a few issues I still need to address and one of them is the low idle when fully warm.
Fully warm: 400RPM
With headlights on: 600RPM
With A/C on: 650-700RPM
I've read through a whole bunch of threads about this issue and most of the cars have at least twice the mileage. Does it seem possible the throttle body and MAF is in need of cleaning?
While changing out the ECT, I noticed a couple things:
1. There is oil leakage coming from the PCV. The whole assembly seemed loose, so I ordered a new PCV and grommet. Will install them when they arrive.
2. A lot of vacuum lines were loose as well. I could pull some of them out pretty easy even though they were clamped. I adjust the clamps to help tighten up the lines.
Still getting low idle at this point. Would a vacuum leak cause low idle?
Any suggestions on other possible things to look at? Has anyone definitely fixed their low idle issue on their VVTI? It seems a lot of the threads I read didn't lead to any resolution.
Fully warm: 400RPM
With headlights on: 600RPM
With A/C on: 650-700RPM
I've read through a whole bunch of threads about this issue and most of the cars have at least twice the mileage. Does it seem possible the throttle body and MAF is in need of cleaning?
While changing out the ECT, I noticed a couple things:
1. There is oil leakage coming from the PCV. The whole assembly seemed loose, so I ordered a new PCV and grommet. Will install them when they arrive.
2. A lot of vacuum lines were loose as well. I could pull some of them out pretty easy even though they were clamped. I adjust the clamps to help tighten up the lines.
Still getting low idle at this point. Would a vacuum leak cause low idle?
Any suggestions on other possible things to look at? Has anyone definitely fixed their low idle issue on their VVTI? It seems a lot of the threads I read didn't lead to any resolution.
01-25-19, 12:05 PM
#2
the low idle is a very common issue. on my 97 (pre-VVTi) I also had the 'problem' and lived with it.
of course when the AC was on the idle would increase, per design, as you noted.
the engine is also loaded when the car is in gear, lowering the idle point further.
the car stalled once in my ownership on a hot day after turning off the AC while in Drive as the idle couldn't hold.
this didn't really concern me though gladly I was on a slow pace through the neighborhood.
a slight vacuum leak may cause rough idle but not really contributing to low idle.
of course when the AC was on the idle would increase, per design, as you noted.
the engine is also loaded when the car is in gear, lowering the idle point further.
the car stalled once in my ownership on a hot day after turning off the AC while in Drive as the idle couldn't hold.
this didn't really concern me though gladly I was on a slow pace through the neighborhood.
a slight vacuum leak may cause rough idle but not really contributing to low idle.
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