'84 suddenly revs uncontrollably to 5500rpm - pls assist in diagnosis

[pcar fanatic]

Hi,

I currently own a 1984 3.2 targa. Its recently had an engine overhaul (1 month ago) and has been running well ever since.

Was driving along today when suddenly, car started to rev at approx 5500rpm. Swithed off the car immediately.

I've checked the accelerator cable and and tried to control it from the engine bay. It seems fine. However, car revs immediately and almost instantaneously to 5500rpm once started.

My mechanic seems to think that the idle control valve may be stuck open or that the brake booster pipe on the manifold may be dislodged ... would this cause such a drastic symptom?

Not really sure how to troubleshoot this .. any help would be appreciated

[john walker's workshop]

cruise cable plastic end popped out and hung up on it's mounting bracket?

[RDM]

Originally Posted by john walker's workshop

cruise cable plastic end popped out and hung up on it's mounting bracket?

This was the problem when I had these symptoms. Look for the square zinc-plated mounting bracket above the center of your engine. The opening is about 1cm square, and the square plastic cable end ought to be poking down through it.

[techman1]

My guess is also your cruise cable. Nothing like having this happen when you left a light quick! Shift into second, engine kept revving, look for a place to pull over!

Seriously, if your closed throttle switch is working, the stuck idle valve would only let the engine rev to about 1200 before the DME would cut the signal and let it drop. Really need a partner to work the throttle in the cabin, and watch it in the engine bay.

[Flat6pac]

You also needy to check the return spring on the throttle console and the two screws that hold the cruise cable to the throttle body, make suretheproper length are used so the throttle doesn't bind as it pivots.
Bruce

[dshepp806]

Cruise, in my case,...long ago. Probably the MOST stressing event to happen in my ownership. I was lucky enough to "control" that event.

Just as JW mentions,...needs to be checked right away.

Best,

Doyle