924Board.org

neophite · Joined: 11 Sep 2008 Posts: 16 Location: georgia

I jumped on a project that was beyond my skills. Replaced waterpump, head gasket, new plugs and wires, distributor cap, rotor.etc..It took me months since I had to redo it several times. Finally got it together and it was excited when it actually cranked and ran. Problem is at idle it runs extremely rough.It was fine before I took it apart.I checked and the timing on the crank and cam are dead on as well as the balance shafts.Any suggestions on my next course of action? Any help will be greatly appreciated.

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Motor mounts???
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erstwhile owner of just about every 924 variant ever made

neophite · Joined: 11 Sep 2008 Posts: 16 Location: georgia

Thanks for the reply. I have read every thread concerning rough idle and
motor mounts seem to be the logical answer. However, there was no problem before I began the repairs and the engine seems to be dropping in rpms. Is there some way to check the mounts or do you think it is a problem in the ignition system?

masterdave · Joined: 10 Dec 2008 Posts: 183 Location: Harrison NY

if the rpms are dropping or changing then it may not be the motor mounts. I had some low idle issues, it ended up being the throttle housing it is very sensitive almost in a bad way. Play around with it a bit, use the idle adjust screw to finesse it. you may find it was just set to low and the engine could not idle correctly

minnesotamatt · Joined: 02 Dec 2009 Posts: 16 Location: woodbury minnesota

how do you adjust the idle speed? my idle is very rough also and it seems like its gonna just die sometimes

bcblase · Joined: 23 Oct 2007 Posts: 574 Location: Winchester, VA

You have one of three problems -

1. Throttle body leak - reseal kit is cheap. (www.paragon-products.com)

2. Vacuum leak, replace with silicone lines. (www.lindseyracing.com or www.paragon-products.com)

3. MAS resistor strip is worn, reset/move wiper arm (www.clarks-garage.com or www.frwilk.com)

I did all of these just to be sure, as well as replaced: motor mounts, throttle position sensor, and a few other things...

Idles and runs smooth as silk now...
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1987 Porsche 924S - track toy
1986 Mercedes 190E 2.3-16v - autocross
2007 F-150 5.4L Lariat Supercrew - tow beast
1994 Volvo 850 Race Wagon - 24 Hours of Lemons Car
2001 BMW 325xi - daily driver

Paul · Posted: Wed Apr 28, 2010 11:09 am Post subject:

Hook up a vacuum gauge and tell us what the needle does at idle

Check the engine grounds (underneath the heater control valve)

Do a compression check

Check your firing order

Make sure the rotor set screw is tight
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

minnesotamatt · Joined: 02 Dec 2009 Posts: 16 Location: woodbury minnesota

ok thanks guys ill get ahold of a vacuum gauge and run some tests and tell you guys how it goes