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Agree that the ECU adjusts and memorizes idle (within a small range), and your explanation of high idle is correct for most situations after a recent MAF/TB/idle port cleaning. However, your explanation does not address low idle, or the fact that the LS430's throttle position sensor has a physical calibration procedure per the attached picture.
After a cleaning, you should do a 10 minute battery pull (my copy of Techstream and/or my cable cannot clear my Canadian 2002's ECM/PCM memory/learned values, but a battery pull is guaranteed to work), followed by 5 minutes of idling in the driveway, followed by a 20 minute drive in-town. If your idle is still incorrect and your idle ports are clean, throttle plate is clean, and there is no cleaner residue/vapors in the MAF or inside your throttle body, you probably knocked your TPS out of calibration, damaged the throttle position motor, and/or damaged the MAF during cleaning.
This procedure does not apply to Marcs’s 2005 LS430
And we're back to 350-400 rpm idle speeds. I wish I knew about not opening the valve by hand as that's what I did. Granted, I was having idle speed issues before, so I don't think I made it any worse. Is there a way to recalibrate the throttle position sensor?
I had the same low idle in gear around 400 rpm. I replaced my VSV and it fixed it.
I had the same low idle in gear around 400 rpm. I replaced my VSV and it fixed it.
Did you have any fault codes or CEL on? Trying to diagnose my low idle and so far have changed out the MAF, spark plugs, and cleaned the throttle body... still there.
Did you have any fault codes or CEL on? Trying to diagnose my low idle and so far have changed out the MAF, spark plugs, and cleaned the throttle body... still there.
its weird. My low idle came back. Currently I have replaced the VSV, every vacuum line, spark plugs, coils, throttle body gasket, PCV, cleaned throttle body, TPS and had it set with the computer. I'm doing the injectors next Wednesday and if that doesn't fix it im doing the intake manifold gasket.. if that downtown fix it im replacing my throttle body with a donor in known working condition to rule the whole TB assemble out. My idle rpm is good in neutral reverse and park but in drive it drops to 450-500 when the ac is off and I'm getting a misfire like stutter at very throttle conditions like cruising but it drives like a brand new car when I give the right foot. Hhhhhmmmmmm
its weird. My low idle came back. Currently I have replaced the VSV, every vacuum line, spark plugs, coils, throttle body gasket, PCV, cleaned throttle body, TPS and had it set with the computer. I'm doing the injectors next Wednesday and if that doesn't fix it im doing the intake manifold gasket.. if that downtown fix it im replacing my throttle body with a donor in known working condition to rule the whole TB assemble out. My idle rpm is good in neutral reverse and park but in drive it drops to 450-500 when the ac is off and I'm getting a misfire like stutter at very throttle conditions like cruising but it drives like a brand new car when I give the right foot. Hhhhhmmmmmm
Sounds like we are tracking down the same thing. I have all the same symptoms except i dont feel any misfire at all when driving, only the low idle with some vibrations when stopped in drive. If I turn of the AC, its nice and smooth at around 800rpm, but turn it off and it usually drops back down. Sometimes its lower than others and sometimes it seems to be just fine.
I just checked my VSV per the procedure in the manual and it was fine, so I can rule that out.
Interesting. I replaced the vsv and everything seemed great for awhile. Even the low idle went away. It mysteriously returned today. I'm debating if my TPS and throttle motor aren't syncing up correctly. My friend is gonna pull his and let me borrow it next week. I want this car for a long time for my kids so I don't mind replacing old parts. How many miles do you have? I'm at 240k.
Next on the list is going through the hoses, though the ones I have checked have been fine so far.
Also I am having the slight misfire/stutter as well as the low idle at the same time and I have been linking those 2 problems together. Now I realize they are separate issues
Also I am having the slight misfire/stutter as well as the low idle at the same time and I have been linking those 2 problems together. Now I realize they are separate issues
The annoying thing is they may be linked, or maybe not, or one could be causing the other. The joys of diagnosing car issues.
Also I am having the slight misfire/stutter as well as the low idle at the same time and I have been linking those 2 problems together. Now I realize they are separate issues
Originally Posted by biosurfer1
The annoying thing is they may be linked, or maybe not, or one could be causing the other. The joys of diagnosing car issues.
Touche lol. It's why I love it. I ain't mad or frustrated just wanna fix it and it never throws codes. Let's keep this alive till we get it narrowed down. this weekend I may pull my intake manifold, replace the gasket, clean it and replace the vac line underneath it. I've done so much at this point it has to be something simple. On a side note I installed MSD coils and Brisk spark plugs. Its a huge difference in acceleration.
