Occasional low idle
06-16-10, 04:03 PM
#1
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Thread Starter
Occasional low idle
I've noticed a strange phenomena with my 2008 is-f where if I'm stopped with the transmission in Drive, the idle will hover around 500 rpms and when I shift into neutral it is back to a more normal 750 rpms. When the car idles at about 500 rpms, I can feel a slightly stronger vibration from the engine. This typically only happens on my morning commute and never happens again for the rest of the day. Does anyone else also notice this or is this a specific issue with my vehicle?
06-16-10, 04:17 PM
#2
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I've noticed this too... at around 500 rpms
Next time do this test.
While out for a drive during the day or morning with lights fully off..
Idle will be low while at a stop light.
Now at the same moment your experiencing this, switch on the lights to either just the 1st click for parking lights or even the 2nd click for head lights..
Idle will quickly raise to 750rpms.
You shouldn't be experiencing this low idle phenomena @ night ..
Joe Z
Next time do this test.
While out for a drive during the day or morning with lights fully off..
Idle will be low while at a stop light.
Now at the same moment your experiencing this, switch on the lights to either just the 1st click for parking lights or even the 2nd click for head lights..
Idle will quickly raise to 750rpms.
You shouldn't be experiencing this low idle phenomena @ night ..
Joe Z
06-16-10, 06:27 PM
#3
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This happens to me all the time. Been happening since day one. Honestly i think it has to do with fuel. On really hot and humid days it happens when i have a certain BP's fuel in the car. But even with the ****ty fuel, a proper amount of lucas injector cleaner stops the problem.
06-16-10, 07:05 PM
#4
This happens to me all the time. Been happening since day one. Honestly i think it has to do with fuel. On really hot and humid days it happens when i have a certain BP's fuel in the car. But even with the ****ty fuel, a proper amount of lucas injector cleaner stops the problem.
06-16-10, 09:51 PM
#7
Driver
Thread Starter
Joe, I tried your experiment tonight and lo and behold, my idle went down when I turned off the headlights and went back up when they were consequently turned back on! LOL. I suppose it's reassuring that other owners are experiencing a similar issue and I may give the Chevron Techron treatment a try.
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06-17-10, 09:12 AM
#10
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Joe, I tried your experiment tonight and lo and behold, my idle went down when I turned off the headlights and went back up when they were consequently turned back on! LOL. I suppose it's reassuring that other owners are experiencing a similar issue and I may give the Chevron Techron treatment a try.
This issue has NOTHING to do with fuel.. I have been using Chevron for over 20,000 miles....
It seems there is an idle setting for when all ACCY's are OFF and then there is a different setting for when a major power draining source is turned ON..
Like Lights or A/C.
Last nite I ran another quick test for you..
Car off ground and in drive idle mode...
Lights OFF = 4 mph with rpms @ approx 600
Lights ON = 14 mph with rpms @ approx 1,100
Keep in mind there was no load on the enigne or tires with the car off the ground..
Which resulted in the constant & measureable MPH.
But the Rpms are reacting the same way when you come to a stop in drive.
Once again NOT a fuel system or fuel brand issue at all...
Joe Z
06-17-10, 07:29 PM
#13
Driver
Thread Starter
If this is just the result of having more load on the engine when the accessories are active, I think Lexus could have fixed it easily via electronic throttle control. Maybe they felt it wasn't worth the effort.
06-18-10, 08:29 AM
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Many people experiencing this with the 250's with many posts on the 250 threads. I have had my '08 250 in 4 times for this and they did a top engine cleaning procedure and it came back shortly thereafter. I have used Chevron since day 1. Lexus Corporate is now telling me it is NORMAL and won't do anything about it. Pisses me off!