What's Your Idle Speed?

**Firebirdjones** · 06-20-2011, 08:07 AM

It's easy like Cutlass said. It's a "do it yourself" job if you have even the slightest mechanical ability.
Just loosen the screws (don't take them all the way out) The blade should slide around freely. Close the throttle blade and move the blade around. You'll see the throttle close even more. You can try snapping it a couple times like Cutlass mentioned.
I've found that if I open it again after it's centered and before tightening the screws down, that it will move again.

I do this all the time with carbs, removing throttle shafts for various reasons. Very easy to center the blades, After it's done and the blades are tight, I like to use locktite on the scews by removing one at a time, so the blades don't move. I also shave them down smooth with the throttle shaft so the threads aren't sticking out in the airway.

**SMWS6TA** · 06-20-2011, 04:41 PM

Ok I did what Cutlass suggested in regards to re-center my blade. No change.......but......

I also looked at the IAC. I cleaned it up and it seems like it doesn't want to move to freely. Like it's gummed up. I pushed it towards the sensor, re-installed and holy shit it idle high quick. Turn her off, pulled it, and then tried pulling it out as far as I could. Re-installed, this time it had a hard time starting, then it did, then idle like crap for a few minutes, then went straight to 1000 rpms. I revved up and it would come down to 500, then try to stay at 800, then it would jump back up to 1000 again.

I'm thinking the IAC is going out or is out?

So whatcha think?

**35th-ANV-SS** · 06-20-2011, 05:50 PM

Can't believe this thread has 1,060 views

Free bump for ya SMWS6TA

**Vexzer** · 06-21-2011, 08:33 PM

Originally Posted by SMWS6TA

I also looked at the IAC. I cleaned it up and it seems like it doesn't want to move to freely. Like it's gummed up. I pushed it towards the sensor, re-installed and holy shit it idle high quick. Turn her off, pulled it, and then tried pulling it out as far as I could. Re-installed, this time it had a hard time starting, then it did, then idle like crap for a few minutes, then went straight to 1000 rpms. I revved up and it would come down to 500, then try to stay at 800, then it would jump back up to 1000 again. I'm thinking the IAC is going out or is out?
So whatcha think?

'puter gotta relearn. Go run it around a bit & it might clear up.

**Firebirdjones** · 06-22-2011, 07:35 AM

Originally Posted by SMWS6TA

Ok I did what Cutlass suggested in regards to re-center my blade. No change.......but......

I also looked at the IAC. I cleaned it up and it seems like it doesn't want to move to freely. Like it's gummed up. I pushed it towards the sensor, re-installed and holy shit it idle high quick. Turn her off, pulled it, and then tried pulling it out as far as I could. Re-installed, this time it had a hard time starting, then it did, then idle like crap for a few minutes, then went straight to 1000 rpms. I revved up and it would come down to 500, then try to stay at 800, then it would jump back up to 1000 again.

I'm thinking the IAC is going out or is out?

So whatcha think?

Sounds like it's either very dirty and needs a good cleaning, or a new IAC. I would think it should have set a code though if the IAC is that far out of whack.

**SMWS6TA** · 06-22-2011, 07:49 AM

I think so too. but I pulled it back off last night and it has moved back to the same position it was in when I pulled off to clean it and do the 1st adjustment. So it's moving some.

I guess I need to send my PCM back to Frost for a tune up. When he did it the first time I had a stock LS1 Intake, now I have a LS6. But the idle has always been at 1000 since I got her. She was all stock when I got her, only was the muffler changed.

So you know what's been done since here's my sig:

**Naaman** · 01-18-2012, 01:06 PM

UPDATE:

Okay, so this is an old thread, but I saw something today that might be helpful to others.

In lab today, we were able to hook up a Modis to our cars and look at various info. My tach still reads about 1050 at idle, but the computer is calculating an RPM that fluctuates between about 790 and 810. The spec is 800, so it's right on target.

Just thought I'd share.

**Vexzer** · 01-18-2012, 02:29 PM

Originally Posted by Naaman

In lab today, we were able to hook up a Modis to our cars and look at various info.

What is a Modis?

Originally Posted by Naaman

My tach still reads about 1050 at idle, but the computer is calculating an RPM that fluctuates between about 790 and 810. The spec is 800, so it's right on target.

Do you mean that the car tach is that far off from the commanded idle or the actual idle?

Thanks for sharing.

**cruzincamaro** · 01-18-2012, 05:42 PM

To Firebirdjones, How did you change your idle on a 6 speed? I have a Diablo Predator tuner and it seems to only want to work on automatics. In selection section it has neutral and in gear. Do you know if this would work on my 6 speed?

**Firebirdjones** · 01-18-2012, 06:24 PM

I haven't messed with the diablo in a long long time, but it should be capable of adjusting your idle speed.

Just for giggles, what is the idle speed set at in the Diablo for the neutral setting? I'm guessing that would be the section used for your 6 speed. If it matches what you are idling right now, try changing that and see if it's affected.

**cruzincamaro** · 01-18-2012, 08:07 PM

Originally Posted by Firebirdjones

I haven't messed with the diablo in a long long time, but it should be capable of adjusting your idle speed.

Just for giggles, what is the idle speed set at in the Diablo for the neutral setting? I'm guessing that would be the section used for your 6 speed. If it matches what you are idling right now, try changing that and see if it's affected.

I was in the "change stock parameters" section. I haven't gone into the diagnostic (engine running) section yet, but that sounds like like a good idea. At least it will tell me if my oem tach is showing the same. Thanks, I'll try it...

**Mr_Rich** · 01-18-2012, 08:21 PM

Originally Posted by Naaman

UPDATE:

Okay, so this is an old thread, but I saw something today that might be helpful to others.

In lab today, we were able to hook up a Modis to our cars and look at various info. My tach still reads about 1050 at idle, but the computer is calculating an RPM that fluctuates between about 790 and 810. The spec is 800, so it's right on target.

Just thought I'd share.

You're not the only one. I was thinking this same thing as I chased the posts down the board. At startup, my tach indicates ~1200 rpms and settles down to ~1000 rpms. I also know this is a high reading since Autotap indicates my car idling at 800 rpms. No big deal. It's off barely the width of the tach needle.

**WhiteHawk489** · 01-19-2012, 12:52 AM

Originally Posted by jrzdude

My idle seems to be a little high after a P&P TB. Is this a normal thing? I can cruise about 25-30 mph without even touching the gas.

my idle was high after i p&p my tb and it turned out to be a lil dirty from the porting and the butterfly hadnt returned completely closed. i believe the idle control motor saw that as the new "0" . to fix: disconnected the tb, rotated the butterfly open/close until the return spring closed the butterfly, reconnect tb and cross your fingers! this worked for me.

**WhiteHawk489** · 01-19-2012, 12:56 AM

oh and my idle is 800

**Naaman** · 01-19-2012, 06:35 AM

Originally Posted by Vexzer

What is a Modis?

Do you mean that the car tach is that far off from the commanded idle or the actual idle?

Thanks for sharing.

Its a snap on diagnostic tool. The factory spec is 800 rpm. The actual rpm was right around 800 plus or minus 10. So the engine is running just as it should. The tach is about 200 rpm off at idle.

**Cutlass** · 01-23-2012, 05:07 AM

Originally Posted by Naaman

Its a snap on diagnostic tool. The factory spec is 800 rpm. The actual rpm was right around 800 plus or minus 10. So the engine is running just as it should. The tach is about 200 rpm off at idle.

Thanks for the update! Someone else found the same thing wrong with there "high idle" just being the tach off a few 100 rpm.

**SMWS6TA** · 01-23-2012, 08:14 AM

That was me..shows 1000 on the stock tack but on 2 diagnostic computers showed 800 rpm.

**Naaman** · 01-24-2012, 10:56 AM

I wonder how common it is for the tach to be off. After taking some readings at different rpms, I've noticed that it's about 200 -250 off (on the high side) at various ranges. Not sure if it happens under load, as I have not tested in gear (might get a chance to in the dyno class, but I'm not that far along yet).

**SMWS6TA** · 01-24-2012, 11:57 AM

my theory is that its worn out over the years, mine has turned 14 yrs old this yr so it's not hard to believe the OEM tach bearings and other stuff has worn down over that time. My fix is going to be getting new one from Autolight with a shift light attached.

**Firebirdjones** · 01-24-2012, 03:57 PM

The only issue I've ever noticed with the factory tachs is they don't ramp up as fast as the engine, but mine have always been pretty accurate otherwise.
I just log mine with HP tuner and it shows as being spot on while idling. As far as shift points, it doesn't really matter. Find where your car runs best and shift it there, whether the tach is off 200 rpm or not isn't a concern so long as you keep using the same tach.