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DISCUSSION => Engine + Driveline => Topic started by: JHZR2 on March 11, 2012, 09:02:51 PM

Title: Post your idle speed range
Post by: JHZR2 on March 11, 2012, 09:02:51 PM

I know M42 engines are known for funny idle, but curious what yours is.

I have been playing with the set screw for the top throttle, as well as the set screw for the ICV (you can chip the brass screw out of epoxy on the ICV and then adjust it to set the gaps in the ICV.  

The computer is smart enough to always revert to the same (low idle speed).

What I generally see is this:  A normal idle speed of say, 550-650 (is there a good way to get the actual speed besides reading the tach?).  AC relay clicks on, engine speeds up to about 800, then slowly dies down to about 600.  Relay clicks off, speed drops a bit to about 550, then picks back to about 600.  

This happens over and over.  Typical?  has always been this way since Ive owned the car, which is about 10 years and 70k.  

But the low idle bothers me, especially since all rubber is good, ICV is newer than 2006, O2 sensor from 2004, no leaks, squeaky clean emissions, good MPGs.  

Normal?  Abnormal?  No idea what is or isnt...

Any insight is appreciated.

Thanks!

Title: Post your idle speed range
Post by: n2motorsports on March 11, 2012, 10:54:16 PM

Quote from: JHZR2;111000

What I generally see is this:  A normal idle speed of say, 550-650 (is there a good way to get the actual speed besides reading the tach?).  AC relay clicks on, engine speeds up to about 800, then slowly dies down to about 600.  Relay clicks off, speed drops a bit to about 550, then picks back to about 600.  

my first m42 did that, got me worried at stops that it'll die in the intersection, but I drove it like that for several years without problems.  on my current m42, it idles a rock solid 900 then "hiccups" and drops to 800 and back to 900.  weird

Title: Post your idle speed range
Post by: willworkfore30s on March 12, 2012, 08:23:52 AM

Was idling at 900 until I pulled to head and intake to paint them.  Now I believe I have aggravated some vacuum leaks because it rev's to 3000 and dies unless I give it gas.

Title: Post your idle speed range
Post by: JHZR2 on March 13, 2012, 01:19:45 AM

Quote from: n2motorsports;111004

my first m42 did that, got me worried at stops that it'll die in the intersection, but I drove it like that for several years without problems.  on my current m42, it idles a rock solid 900 then "hiccups" and drops to 800 and back to 900.  weird

Yeah, hiccups is a good way to describe it!