Idle at tach lower than reading at engine
 

Chasing a good idle. 1986 3.2l...

Just got in an automotive multi-meter and am reading 790-820rpm at the engine but the tach is showing right/well below the 750 mark. Idle is steady...

I have always felt it read low and now have some verification. Is this a situation to send it off for calibration or is this something I can do/adjust myself?

I have searched and only come up with "bouncing tach" threads...

Car is running/idling great just my tach is reading low.

Thanks for any insight-
Erik

increase the idle a little and see..here some reading for you..
Ivan
http://forums.pelicanparts.com/porsche-911-technical-forum/6709-3-2-idle-speed-adjustment.html
..http://forums.pelicanparts.com/uploa...1703022161.jpg
http://forums.pelicanparts.com/uploa...1703022161.jpg

Thanks for taking the time to answer.

That's a great thread and I can't believe I've never read that one. I have been searching the forums for weeks and that never popped up.

Funny what shows up and what doesn't.

Couple things I took from that is...I will swap out tachs and see if my other one reads more accurately and a few of the gents in the thread hinted at maybe setting the idle a bit higher.

My 911 today seemed to idle better at 820 +/- (on average) vs the 800 it's supposed to be. Seemed to start better when cold and kept a smooth idle in stop and go traffic.

I know later versions are supposed to be 880 and mine should be 800. Maybe 820/830 rpm is my sweet spot.

I am pretty happy with where it's at and showing 820+/- on the multi meter. Just hard to look down and see the tachometer showing 700-ish.

Again, really appreciate the link and you taking the time.

Erik