500 rpm idle ?
Thread Starter
Teching In
Joined: Oct 2005
Posts: 12
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From: currently .. South Carolina
500 rpm idle ? A couple of weeks ago I put some longtubes, and a custom true duel x pipe with no cats on my internally stock 99 z-28 m6. I kept the egr stuff on there because I wasnt sure what I can take off yet. Sinse having no rear o2 sensors, my SES light was on. I plan on doing a cam this month and I was going to get the car dyno tuned after all the mods. Today my SES light went off and my idle is aout 500 rpm. Did the computer automatically adapt to my unfinished mods. Is there a way to adjust my idle manually without all the computer stuff. Thanks
Joined: Nov 2001
Posts: 34,638
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From: Schiller Park, ILL Member: #317
Stock M6 idle speed should be 800rpm.
High or low idle speeds can be due to quite a few things, A/F issues (due to tuning, bad sensor readings, exhaust leaks, or vacuum leaks) are one major reason.
The idle can be manually raised via the TB set screw to a point, but before doing that I'd question why the idle is suddenly so low? Better to fix the problem than cover it up. Was it always low, or did the recent mods cause it?
Other possibility is, maybe the gage is off for some reason? Did you verify idle speed via a scanner? Should always be in the 750-850rpm range at steady idle on an M6 with stock tuning.
High or low idle speeds can be due to quite a few things, A/F issues (due to tuning, bad sensor readings, exhaust leaks, or vacuum leaks) are one major reason.
The idle can be manually raised via the TB set screw to a point, but before doing that I'd question why the idle is suddenly so low? Better to fix the problem than cover it up. Was it always low, or did the recent mods cause it?
Other possibility is, maybe the gage is off for some reason? Did you verify idle speed via a scanner? Should always be in the 750-850rpm range at steady idle on an M6 with stock tuning.
Joined: Nov 2001
Posts: 34,638
Likes: 2,564
From: Schiller Park, ILL Member: #317
Originally Posted by SVThis
what about an A4?...mine has alway idled around 500
M6s have a higher stock idle speed.
A4 stock idle speed is 550rpm in gear and 650rpm in park/neutral. The factory tach is not exact so if it's anywhere in the 500-700 or so range, then it sound like you're just fine. If you want to be real sure of the actual idle speed, hook up a scanner and check it out.
As an example, my '98 shows via the tach that my fully warm idle in gear is about 650-750rpm. But when I hook up my scanner, it shows ~550rpm as it should.
Thread Starter
Teching In
Joined: Oct 2005
Posts: 12
Likes: 0
From: currently .. South Carolina
I never thought of the throttle body or mass air flow sensor. I was playing with it today, and rpm idle seems to be back to normal. I couldnt imagine what would cause that. I'll figure it out. Thanks for the help
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