crazy reving problem

[ramonesfreak]

i was just driving along on the highway going about 55. i had to exit so i took my foot off the gas pedal and pressed in the clutch pedal.

when i did this, the engine started revving on its own to redline and seemed like the gas pedal was depressing on its own....i managed to exit and got on slower streets and it calmed down and i was able to drive home ok.

any ideas? car has been running perfect otherwise

[Dantilla]

Does your car have cruise control?

[ramonesfreak]

yes. and thats the first thing that came to mind. i was not using it at the time but it was as if the car became possessed...due to the gas pedal depressing on its own


the cruise control has always worked great by the way

[ramonesfreak]

how do i diagnose this?

can i disconnect the cruise control? this problem was very dangerous for a moment

[myfast911]

start at the pedal cluster and work your way back. sounds like the cluch cable is bound up with your throttle cable.

[ramonesfreak]

pedal cluster seems fine. working back, im not sure where to look. honestly, it seemed more electrical than mechanical.

[ramonesfreak]

just to be more specific...

i was NOT using the cruise control at the time this occurred

the sensation was like the cruise control activated on its own when i pressed the clutch in, in order to downshift to 3rd. at that moment, once clutch was in, i felt the gas pedal under my foot go towards the floor and the tach went to redline.

i then let clutch out and it stopped revving.

once i was on side-streets, i had to stop 4 times at red lights and shifted normally between 1-2-3 and then was home no problem

[ramonesfreak]

according to my Bentley book. the cruise control has a clutch switch which turns off the cruise control once the clutch pedal is depressed. therefore, i cant imagine the cruise control suddenly turned on - since i had the clutch in when this happened.

[ramonesfreak]

for reference, a similar thread:

http://forums.pelicanparts.com/porsche-911-technical-forum/394455-gas-pedal-gets-stuck-sometimes-post4045132.html#post4045132

[Brorag]

dangerous............
I had the same result when I swapped what appeared to be two identical relays, when searching for a cruise control inop issue. The relay is in the large box in the front trunk.
try removing the cruise relay and see if that stops the problem.

[ramonesfreak]

ill look for it. thanks. it was not a good thing to happen with highway traffic and im worried about my engine now revving to redline....55 mph, clutch in, tach to 7,000 rpm before it stopped

note: i havent messed with my cruise control. it works fine. well, sort of. when first engaged, the engine surges a bit and then settles down to the proper speed...which I understand is normal..or typical. I also dont understand how the CC can do anything if it is not "on".

but, to be safe for now until I fiture this out, Ill eliminate the CC

[haycait911]

my vote is still for crossed-up cables. the description is classic. FWIW.

[Thrlls]

Originally Posted by haycait911

my vote is still for crossed-up cables. the description is classic. FWIW.

+1...depress clutch and accelerator goes down, sounds like cables and rods are either rubbing or something (road debris) snagged them together.
Look under the car where the clutch cable and accelerator rod are located.
Then double check the pedal cluster again.

[ramonesfreak]

if they were crossed could it be happening in the tunnel?
im thinking that the sensation of the gas pedal going down was in my head. im hoping that the cruise control cable got stuck because i found a broken plastic sleeve. see below. ill check for crossed cables though

[JohnJL]

Sounds like crossed cables or a broken throttle return spring/gummed linkage. Yes, they can cross in your tunnel, however first check you have 2 return springs; 1 on hte transmission case to the pivoting linkage and one on the throttle body itself.

Have someone work the throttle (engine off!) and check every linkage for binding.