I was wondering if I have a problem or if it was normal. I notice that my '97 LT1 doesn't idle "smooth as butter". The tach shows a steady 800RPM, but I can sense a slight "roughness" in the idle, which may be interpreted as a slight miss. I recently changed the Opti, serpentine belt, plugs and wires, and water pump all at the same time. It idled the same way before the service. It doesn't sputter or try to die on me..I just never really noticed that it idled "rough". No SES codes are on either.
While at speed, it runs great.

 

I notice the same thing and it bothers me each time I start my car. I think it is a combination of the open loop when I first start the car and the sound/feel of the exhaust popping and flowing through the LT's and Y-pipe. I dont remember is being so noticeable until after my header install.

-Dustin-

 

I idle was horrible at one time, cleaned my iac sensor and now it's pretty steady. This idle is no rolls royce... but it's nothing to complain about. Video in sig.

 

Well i would not exactly call mine "smooth" but it idles good.

 

i'm with nick...mine idles nice and choppy. It shakes the whole car and I love it.

 

If it were up to me, I wouldnt have a smoothe idle again.

 

depends on if its had a tuning recently...

give me 10 hours under the hood fiddling around poking at stuff and replacing wires, plugs, filters, etc, it idles at 500 rpms as if it were off, no movement...
and thats at 106k miles, but when its not tuned it shakes back pretty good and its not uncomfortable just kinda annoying

 

Like a baby's @ss.....

 

Not smooth at all. It's steady enough at 800rpm and the exhaust feels smooth (no missing) but it just shakes. But mine also vibrates at RPM, which I think is a crank damper issue. I wonder if that could be causing idle roughness as well.

In one of my recent datamaster logs, I noticed the spark advance at idle can vary by as much as +/- 4° so maybe I'll see if I can get it to idle with a steady spark advance, then see if that helps anything. Probably won't.

Then there's the issue of just how smoothly an M6 LT1 Camaro is supposed to idle. My friend has a 94 T/A A4 and it's noticably smoother. The torque converter helps. But these aren't exactly the most refined cars anyway. I mean, when I get out of the Camaro and hop in my Caprice, for the first few miles, I could swear I'm driving a Lexus...

 

Mine is very smooth. 140000 miles with original opti.

 

how did you clean it?

 

The idle in mine got significantly rougher after I installed my headers and put polyurethane motor mounts in it, that is the car shakes quite a bit more now. But I am not complaining.

 

Pull it off of the Throttle body, and spray with carb cleaner till it's shiny again. I have always pushed the plunger all the way back in, before I bolt it back in place.

 

If your "tach" is reading 800 and the tachs usually read a couple hundred high, I'd guess that you might actually be idling too slow. My pcm is progsrammed to idle at around 950 with my little bitty cam and if idles quite nicely.

However, if I was reading 950 on my tach, I would, in reality, be idling around 750 which would probably mess with my idle. (M-6) JMHO

 

thanks for the info
do you have to take the TB off to get to it?