Idle Jitters No Codes

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2000 Buick LeSabre w/ 3800 V6 -- Mileage 126,580

I'm just throwing this out there in case anybody has some ideas. The idle is not terrible, but it's not new car smooth either. I can put my hand on the engine cover and feel the jitters. I know I should hook the car up to a live data scanner, but I don't have one. You guys are welcome to take some guesses.
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Hi Colt,

The plug wires were changed at about 100K along with new plugs.
The coils are all original, but the ICM has been replaced.
 
I would change out the PCV valve. My pop's 93 LeSabre with a 3800 had a rough idle. It was due for plugs and wires so I swapped them out and the idle was still not great, so I changed out the PCV valve and it smoothed out a bit.

These engines were never the smoothest given its design history and pedigree. But I am willing to bet that PCV has never been changed.
 
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Originally Posted By: SR5
Sounds like the oil may be a little dirty. Do you change it frequently enough ?


I think it's the varnish causing the vibration LOL!

Sorry Merk, it's hard to resist. But seriously, I got nothing, I don't even think it's a problem when you have to put your hand on the engine and only then you feel some vibrations.
 
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Just find a scanner to at least pull codes to see if there is any stored codes to look at. We can throw diagnoses at you all day long, but it is all just random without a starting point for a diag.

Random suggestion #1....Ck for vac leaks. This is where codes are nice. You might have a lean code to help out, maybe even a misfire code stored to help as well.
 
Originally Posted By: punisher
Just find a scanner to at least pull codes to see if there is any stored codes to look at.


I have a code reader, but not a scanner to see live data. I got a P0452 code earlier this week, but I always get that code about once a year when the weather heats up. I don't think it's related to the idle issue.
 
Pull out the IAC valve and clean it with throttle body cleaner and wipe the pintle and the seat down good. That is the easiest engine in the world to clean the IAC valve
 
Lazy O2 sensors can cause a shudder, the engine hunts around slightly adjusting the fuel trims and it relies on O2 readings to do this. O2 sensors get slower to respond as they get old but not to the point that they trip a code, the slow response causes the trim adjustments to lag and the air fuel ratio to be less than ideal and not as consistent as it should be.
 
Pull the plugs and look at them, maybe there's a bad injector or something. You should be able to read the plugs and see what's going on.
 
Originally Posted By: ironman_gq
Lazy O2 sensors can cause a shudder, the engine hunts around slightly adjusting the fuel trims and it relies on O2 readings to do this. O2 sensors get slower to respond as they get old but not to the point that they trip a code, the slow response causes the trim adjustments to lag and the air fuel ratio to be less than ideal and not as consistent as it should be.


You got me curious about that Ironman. The O2 sensors are all original from day one.
It sure would be nice if all I had to do is plug in a new O2 sensor to get a smooth idle.
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some good replies here.I would clean iac, put in a new pcv, and give it a dose of a cleaner with pea.if this does not help, check out the o2 sensor.don't get crazy about this, since it's minor in nature.good luck
 
Motor mounts have been replaced and the IAC was cleaned when I cleaned the throttle body last year.

Mobil Super HM 10W-30 was put in Wednesday night. I only had 2995 miles on the SuperTech synthetic but is was almost black. OLM was down to 25 percent.
 
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