rough idle
11-10-2002, 09:10 PM
#1
Intermediate
Thread Starter
Join Date: Nov 2002
Location: Tulsa, OK
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
rough idle
low rpms goes from 1100 and then drops from 1100 to 600 and stays very rough around there. Changed plugs (they were fouled)thinking distributor is next or maybe coil?
11-10-2002, 09:45 PM
#4
Race Car
Join Date: Jun 2002
Location: Costa Mesa, California
Posts: 3,781
Likes: 0
Received 0 Likes
on
0 Posts
[quote]Originally posted by kami:
<strong>sorry '84 944 n/a</strong><hr></blockquote>
Add this to your signature line -- helps.
There seems to be a rash of throttle bypass valve stickies lately. Also called the Auxiliary Air Valve and the Idle Positioner depending on the year and the translation of the particular repair manual you are looking at.
This valve in the 83's, 84's and early 85's has a bimetallic spring attached to a sliding valve (knife valve) and is opened by heating the bimetallic spring.
The valve sticks from gummies in the vacuum lines. The valve is located under the intake manifold plenum. That's the large round part before the long runners into the head. You can just get to one of the large vacuum hoses attached to it and pull it off.
Spray the heck out of it with brake/carb cleaner a few times then a spray of lube such as WD-40 then put the vac hose back on tight. Make sure the electrical plug is back on tight too.
If this doesn't do it then you may need to clean and reset the throttle position switch.
<strong>sorry '84 944 n/a</strong><hr></blockquote>
Add this to your signature line -- helps.
There seems to be a rash of throttle bypass valve stickies lately. Also called the Auxiliary Air Valve and the Idle Positioner depending on the year and the translation of the particular repair manual you are looking at.
This valve in the 83's, 84's and early 85's has a bimetallic spring attached to a sliding valve (knife valve) and is opened by heating the bimetallic spring.
The valve sticks from gummies in the vacuum lines. The valve is located under the intake manifold plenum. That's the large round part before the long runners into the head. You can just get to one of the large vacuum hoses attached to it and pull it off.
Spray the heck out of it with brake/carb cleaner a few times then a spray of lube such as WD-40 then put the vac hose back on tight. Make sure the electrical plug is back on tight too.
If this doesn't do it then you may need to clean and reset the throttle position switch.
11-10-2002, 09:54 PM
#5
Intermediate
Thread Starter
Join Date: Nov 2002
Location: Tulsa, OK
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
thanks I was messing with the vaccum hoses and on the passenger side I would touch the under side of one on the drivers side of the throttle cam and it would idle up then
thanks will try that
thanks will try that
11-10-2002, 09:58 PM
#6
Race Car
Join Date: Jun 2002
Location: Costa Mesa, California
Posts: 3,781
Likes: 0
Received 0 Likes
on
0 Posts
If you have a vacuum leak it's best to find it and fix it.
Sometimes the rubber boss on the large rubber intake tube between the AFS and the throttle body breaks off at the tube.
Fix the vacuum leak first.
Sometimes the rubber boss on the large rubber intake tube between the AFS and the throttle body breaks off at the tube.
Fix the vacuum leak first.
Trending Topics
11-11-2002, 09:21 AM
#8
Pro
Join Date: May 2001
Location: Annapolis, MD
Posts: 552
Likes: 0
Received 0 Likes
on
0 Posts
The easiest way to verify its the Aux Air Valve, or the Idle Control Valve, is to tap it with a screw driver handle when you car is idling rough. It it's smoothes out, there you have it.
11-11-2002, 09:55 AM
#9
Drifting
Join Date: Jan 2002
Location: Central Florida
Posts: 2,258
Likes: 0
Received 0 Likes
on
0 Posts
I recently had vacuum hose troubles too. Sometimes (usually when hot starting) the car would just not idle and frequently stall. Sometimes it would run fine. I had this problem on and off for probably a year. At the DE last month it decided it wasn't gonna cooperate for my last session so we went in and looked at all the lines, and sure enough one of the vacuum lines was like mush, completely disitegrating.
So we went and got some rubber hose and jury rigged it with that until the right hose comes in from Porsche. But now the car runs perfect, and it even seems to have stopped my pan gasket leak as well.
So we went and got some rubber hose and jury rigged it with that until the right hose comes in from Porsche. But now the car runs perfect, and it even seems to have stopped my pan gasket leak as well.
