[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: another high idle problem 87 5kcst auto tran

-----Original Message-----
From: LOACESQ <LOACESQ@aol.com>
To: quattro@coimbra.ans.net <quattro@coimbra.ans.net>
Date: Monday, May 11, 1998 9:31 AM
Subject: another high idle problem 87 5kcst auto tran

>Hi list,
>After a stretch of highway driving at around 85, I noticed as I was slowing
>down coming into the city that the idle was unusually high, as if the
>control were stuck on.  Flipped the cruise switch, no improvement.
>Disconnected the cruise module, no improvement.  Put her in neutral, the
>rises quickly and steadily to 3000.  Work the throttle, the rpm goes up
>3000; release throttle, rpm slowly comes back down to 3000.
>Later at home, I check the ISV.  There's no crud and it seems to be
>freely (hoses off, electrical on, you can see the valve oscillating).
>Reinstall the ISV, unplug the green connector on firewall, idle rpm still
>climbs to 3k.  Unplug the electrical connector to the ISV, same high idle.
>Unplug the WOT switch, same high idle.  Undo the ic/tb hose and check the
>plate in the throttle body--it opens and closes fully and freely.  Throttle
>linkage is fine.  Unplug the ISV temp sensor, no change.  Unplug the ECU
>sensor, no change.  Ground each temp sensor connector, no change.  Swap the
>temp sensor connectors, no change.
>Could the idle speed adjustment screw cause this problem with a broken
>Fuel distributor air flow metering plate stuck?  Spring broken?
>The car is automatic transmission.  Anyone remember what that trick was 60
>Minutes used to induce unintended acceleration?

Hi Adam;

    I had a similar problem on both my '86 5ktq and my '91 200q. After
prolonged highway driving, the engine would idle high. It was indeed cruise
control related.  The actuating rod from the cruise control motor is
connected to the throttle bell crank with a ball joint. On both cars, over
time the joint filled with grit and other debris - the resultant friction
prevented the throttle from returning to the fully closed position. I pulled
the joint apart, cleaned out the socket (the socket has a plastic liner),
polished the ball with 0000 steel wool, & lubed with WD-40 (the real stuff,
not the diluted spray stuff). Voila, problem solved.
    Hope your fix is this easy!


Fred Munro
'91 200q  251k km