How Smooth Is Your Idle?

Messages
1,151
Location
Clovis, CA
My Buick with its 3800V6 has a little bit of a "buzz" at idle. Just enough for me to feel through the steering wheel and shake the rearview mirror. This is annoying to me, and I wish I couldn't feel the engine at all. I know there are some cars out there that you can't feel (or hear for that matter) idle at all. The brand Lexus comes to mind. What about your car or truck, what kind of idle do you have?
 
Messages
513
Location
Funny Farm
idle in my 140,000 mile '94 4runner is so smooth i can't explain it. 500rpm with the a/c on in the 100F+ heat. 850rpm w/out a/c. Idle in my 1990 Turbo supra is also perfect. 95K on it.
 
Messages
873
Location
Shreveport, Louisiana
On my '02 Land Rover w/77,000 miles, I thought it was pretty smooth, that is until a couple of weekends ago I changed the plugs and wires. Boy did it make a big difference. Now it is smooth, no shake, shimmy or noise of any kind. It idles at about 750 rpm, running Redline 5w40.
 
Messages
9,365
Location
USA
hate to say it, but its a GM; (uh oh, I can feel the flaming coming from GM owners) [poof] Toyotas I swear I can't even hear the engine when it accelerates let alone idle.
 

JTK

Messages
13,432
Location
Buffalo, NY
The 4.2L inline 6 in our 2005 trailblazer idles so smooth you can't feel it at all. The 3.8L V6 in our 2001 ford windstar gives off a little vib'n shake. Still an awesome runner tho. Joel
 
Messages
1,043
Location
Central IN
Yeah, eventhough the 3800 isn't the smoothest machine out there, it is pretty bulletproof. The 3400 V6 in my '00 Grand Am has a rough idle. My '05 Mazda3 2.3L 4-banger is as smooth as butta!
 
Messages
1,043
Location
Central IN
By the way, my best friend has an '02 Trailblazer. Like JTK said, it's very smooth. They actually made the ignition so that if the engine is already running and you go to try to start it again, it won't do anything. I think they did this because it is so smooth and quiet, you can't tell when it's running.
 
Messages
432
Location
central Georgia
Our lesabre 3800 idles quite smooth. My previous Olds with the 3100 [gasp] was really smooth. My Firebird 3800 is a little less so... My guess on the Lexus etc. would be those liquid filled, high-isolation engine mounts...
 
Messages
3,094
Location
Metro Detroit
When I last changed the spark plugs in my 3800, there was a noticable improvement in idling and overall power and NVH (noise-vibration-harshness) levels. If it's been a while (60-80k on factory plugs), I'd recommend that. I went with AC Delco iridiums. I've also heard a good intake cleaning will do wonders. My Monte Carlo has a low hum at idle. There is only the slightest vibration. It's perfectly acceptable to me.
 
Messages
1,268
Location
SoCal, CA USA
My new SCION tC (Camry 2.4l engine) is silky smooth - and I have 4k miles on it! So who knows, after it's broken in, it might be better [Smile] Scott
 
Messages
656
Location
Massachusetts
My 5.3L V8 is smooth as silk. The previous truck I had was a Ford with the useless 4.2L V6. It idled as if someone was dumping a bag of marbles in the intake. I liked everything about that truck besides the engine.
 
Messages
3,094
Location
Metro Detroit
quote:
Originally posted by Ray H: 60 degree V6s, even with offset crankthrows, will have some vibration at idle. (engine mount design can moderate that to some degree) If I'm not mistaken, GM has at least one V6 engine series equipped with a valley-mounted balanceshaft. I6s with fully balanced and 7 main bearing supported crankshafts have always been among the smoothest engines made - to whit, BMW's legendary "turbine smooth" inline 6-cylinder engines.
The 3800 is a 90* V6 with a valley-mounted balance shaft. At the engine's original inception (late 50's or 60's I think), it was basically a V8 with two cylinders chopped off. This made it cheaper to manufacture since they could use the same tooling to bore the cylinders (or so I've heard). They later refined it with the balance shaft, which smooths it out significantly, but no balance shaft is perfect. That's why you'll always get "some" vibration from these motors. They're normally very quiet, though, being right on par with most 60* V6s. My car used to be unnoticably quiet at idle when it was new. After 106k miles, though, you can hear it a bit. It's still nice and quiet, though, as I noted above.
 
Messages
119
Location
Atlanta, GA
My 3800 w/ 127k starts effortlessly. It will idle somewhat smooth with the occasional burp the first few minutes. It never idles smooth as silk though, and I can hear it at all times. Doesn't really bother me. I did change the plugs (ACDelco), wires, PCV, and it helped a lot with the idle.
 
Messages
36,461
Location
ME
My intrigue 3800 is smooth compared to my saturn 1.9s. The intrigue has two dogbones going to the radiator support and all the other mounts are down low somewhere. I've seen the same motor in a bonneville with a different mounting system. You could have a resonance starting, either from hardened/softened rubber in a mount, or an idle speed just slightly out of factory spec. The idea posted above about an intake cleaning (particularly the IAC) sounds good. Do you have the same buzz in drive as in neutral? Does a load like A/C make it go away or get worse?
 

GoldenRod

Thread starter
Messages
1,151
Location
Clovis, CA
eljefino, The car used to be as smooth as a Lexus. It gradually has gotten worse since I bought it last August with 83,000 miles on it at the time. It still has its original spark plugs, ignition wires, coil packs, sensors, and components. The only things I have ever done to it is change air filter, window regulator, cabin air filter, wiper blades, DexCool, and of course oil and filter. I haven't peeked into the throttle body yet, nor have peeked at the EGR valve either. But I'm thinking about maybe cleaning both of them if it would improve the idle. The IAC valve is right there in plain reach next to the MAF sensor. I am good at mechanical repairs and maintenance. I also have learned from experience, that it is better to leave something alone, unless I know for sure that it is the culprit. [Big Grin] One more thing I might add: I'm still trying to conjure up a plan on accessing the rear spark plugs, as they are not in plain easy reach. Not even close. [SPAZ!]
 
Messages
4,497
Location
Massachusetts
The 2.5L in my mostly '92 Jeep Wrangler idles pretty well even when the Jeep sits on it's side, waiting to get pushed back on it's tires. [crushedcar]
 
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