home register FAQ memberlist calendar

Go Back   Turbobricks Forums > Mechanical > maintenance & nonperformance

Thread Tools Display Modes
Old 08-24-2010, 12:48 AM   #1
Board Member
Join Date: Mar 2009
Location: Lynnwood WA
Default Wavering idle, poor vacuum

Hi, I have been getting a rather poor idle, it wavers between 500-600 rpm fairly rapidly and causes the motor to shake lightly when it drops down to 500ish range. My aftermarket boost gauge only indicates about 12 Inches mercury for vacuum.

I am aware that I have an ACC problem, vents/ac/heat cut out when in boost. Could this problem be related? Could air be leaking in from the ACC system?

I'm running on a fresh rebuild, new vacuum hoses, cleaned the AMM.

I really want to install my new V cam, but want to get this squared away first cause I know that will only make vacuum worse.
Ninja007 is offline   Reply With Quote
Old 08-24-2010, 03:05 AM   #2
Cooks with motor oil
Join Date: Aug 2008
Location: nut Sac, Cali

Make sure you don't have any vac leaks. Ya can kinda check your AMM by unplugging it. That ought to make your car run really crappy. When ya plug it back in, it ought to run regularly.

If everything else is working properly (might not be the case), you can up the idle by turning the big thumb screw on the throttle body.
1988 740 turbo wagon/squishmobile!
gottarollwithit is offline   Reply With Quote
Old 08-24-2010, 05:04 AM   #3
Board Member
6kYellowLine's Avatar
Join Date: Dec 2007
Location: Tigard, Oregon

you might have skipped a tooth on your cam or crank.
Check your timing marks
Originally Posted by uvwx310
whole body edema after ugg baby boots
6kYellowLine is offline   Reply With Quote
Old 08-24-2010, 11:16 AM   #4
Drunk as ****
Canuckvolvo's Avatar
Join Date: Nov 2002
Location: Beautiful BC

read the brickboard faq to fix your acc problem, just did this on my 940. it shouldn't affect idle/vacuum though. More likely timing or vac leaks as mentioned.
Currently Volvo-less
Canuckvolvo is offline   Reply With Quote
Old 08-24-2010, 12:28 PM   #5
Masked Moogle
MistrThou's Avatar
Join Date: Oct 2004
Location: Janesville, WI

Do a quick check for a vacuum leak in the engine compartment. Buy some carb/ throttle body cleaner, and spray anywhere there's a connection around the intake manifold or hoses going to it (if a turbo). If the idle changes at all, you can find where your leak is.
Originally Posted by Old Guru
Current cars: Something old, something new, something borrowed, something Maroon.
MistrThou is offline   Reply With Quote
Old 08-24-2010, 12:50 PM   #6
Kickin' rocks in sandals
Chris_R's Avatar
Join Date: Jul 2003
Location: Loganville, GA

Good info on vacuum problems here:
Originally Posted by Turbo Joe View Post
Ermergherd!! Erm gernner kerhm!!
1995 964 (Silver)
1992 944Ti (White)
1996 965 (Burgundy) - Scrap
1994 945 Ti (Black) - Sirius Black Scrap
1992 944 GL (Black) - Killed by drunk driver
1988 745Ti (Silver) - Sold
Originally Posted by TurboBrickMan View Post
Long story short I found out she's a squirter.
Chris_R is offline   Reply With Quote
Old 08-24-2010, 10:43 PM   #7

I had a slightly milder issue with a faulty distributor...

also, like the other dude said...mechanical timing might have skipped a tooth or something (unlikely) but if you want to swap cams I'd go ahead and do it, that way you will know timing is 100% before diagnosing this problem. I'm pretty sure it's electrical..
  Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

All times are GMT -4. The time now is 07:07 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.