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-   -   Interesting valve adjust result. (http://forums.pelicanparts.com/porsche-911-technical-forum/736408-interesting-valve-adjust-result.html)

SilberUrS6 02-27-2013 09:13 AM

Interesting valve adjust result.
 
After a valve adjust on my 3.2, the idle is about 100RPM higher when the car is warm. Cold idle is about 200 RPM higher.

If nothing was touched other than the valve covers and the valve adjusting bits, why would this be true?

Reiver 02-27-2013 09:18 AM

You tuned it up...now it breathes and exhales better is all.

DaddyGlenn 02-27-2013 09:43 AM

How far off were the valve adjustments?

SilberUrS6 02-27-2013 10:41 AM

Quote:

Originally Posted by DaddyGlenn (Post 7299227)
How far off were the valve adjustments?

It didn't seem like much. I *did* touch all of them up, however. It didn't seem like there was any glaring gaps or lack thereof. Maybe my unskilled hands can't tell???

redstrosekNic 02-27-2013 10:44 AM

Does the car sound any different after the adjustment (more or less clatter)?

Chuck.H 02-27-2013 10:57 AM

You sure you didn't knock a vacuum hose loose?

Idle should be set by the ICV, not by 'tune of the engine'... unless the idle bypass valve was at it's limit of adjustment (too far open) and the ICV can't adjust the idle down far enough?

Chuck.H
'89 TurboLookTarga, 347k miles

SilberUrS6 02-27-2013 11:07 AM

Quote:

Originally Posted by Chuck.H (Post 7299388)
You sure you didn't knock a vacuum hose loose?

Idle should be set by the ICV, not by 'tune of the engine'... unless the idle bypass valve was at it's limit of adjustment (too far open) and the ICV can't adjust the idle down far enough?

Chuck.H
'89 TurboLookTarga, 347k miles

I could have, but I don't think so. Wouldn't a big vacuum leak after no vacuum leak make it idle lower??? And driveability hasn't changed.

It did have a bit of noise before the adjust, when the engine was cold. After, it was clatter-free. Sounds like a sewing machine when first started up. :)

E Sully 02-27-2013 11:53 AM

Minor valve adjust by itself would not change the idle on the 3.2. DME controls it through the Idle Control Valve. You say the warm idle is 100rpm higher, fairly small change, but more relevant is the actual rpm. Assuming that you still have the stock chip installed, does it idle at 800 rpm?
I would make sure that the O2 sensor was still connected, those connectors tend to disintegrate from age and heat. I would then reset the base idle using the jumper in the port by the electrical panel. When the jumper is removed, see if it holds a steady 800 rpm, but drops a little when the oil cap is removed.

DRACO A5OG 02-27-2013 12:37 PM

+1 check for vacuum leaks, buddy's 86 3.2 had a leak and he had higher idle, after vavle adjust and chts fix, it was higher so we checked his base idle and it was set too high, adjusted and all is well.

Guardsred911 03-24-2013 07:10 PM

I had similar results, but on the '80 SC after dropping the engine, re sealing the triangle of death, new headers and exhaust, as well as valve...

I did have a backfire that popped the Pop - Off valve glue, which I fixed... but I looked closely for cracks and saw none

Similarly, I seem to be slightly higher... 200 at cold and 100 at warm... any suggestions on setting it?

(and yes, still scrolling through the list of posts, but this one seemed fresh and relevant)

So I just went into the garage and found the idle adjustment screw... I am wondering if I tweaked it when I dropped and reinstalled the motor... and all the other work I had been doing...

Jdub 03-24-2013 08:04 PM

It wasn't until I did a valve job on a Honda 400/4 (400cc 4cylinder) that I understood what opening up the valves meant. A choked (read: tight valve) drivetrain won't make much noise and won't idle well. Getting the recessed valves to now open at the proper adjustments will increase idle and let you hear the valves sing. The toughest valve job you will ever do is on a 911 tho. - no question!

LakeCleElum 03-24-2013 09:57 PM

I had the same result (higher idle) with a 911 once. The valves had not been adjusted in a long time and were on the tight side.
My theory: Valves weren't quite closing all the way and losing a little compression? It certainly was not a vac leak.


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