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Stuck Throttle (in the Mountain Twisties, no less!)

 
Old 10-03-2005, 05:38 PM
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Ed Scherer
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Question Stuck Throttle (in the Mountain Twisties, no less!)

A couple of weeks ago, I was driving the twisties in and around Estes Park, Colorado (see post #58 in "Best Roads In America for the 928" thread for general comments on that great trip).

Anyway, my throttle stuck three times (including once with my wife in the car) while driving these twisties. Rather high pucker factor. Especially the last time, which was at WOT after having reentered the road (from a turnout; stopped to take some photos) in front of some traffic.

It's remarkably hard to haul the car back down to a stop when you can only leave the road at the next available turnout (which aren't very closely spaced). Didn't want to cut the engine too early, either, since I didn't want to get caught going uphill with nowhere to pull off. So... the torque converter got quite a beating.

I'm about 99% sure I finally figured out what was going on the third time it happened (the other two times, it "fixed itself" shortly after stopping). The third time, however, when I popped the hood and took a look, I found the socket at the end of the throttle body cable at a strange angle. It was stuck at that position (see animated photo below); a little pressure, though, popped it down into the proper position again and I was good to go. Luckily, the previous day, I had the foresight to put a small container of oil in the car. Lubricated this ball/socket and it has been fine ever since.

But... this episode had me thinking about doing some preventive maintenance on these cables, guides, and the ball and socket connections. Some questions for those of you that might have had similar problems (or might have some of problems similar to what I'm about to describe):
  1. Has anyone else experienced a stuck throttle like this? Did it take anything beyond just lubricating the ball/socket connections? Any preferred lube?
  2. Note that the little rubbery, amber-colored, conically-shaped guide that used to be on my accelerator pedal cable split into a few pieces and eventually fell off (see the second photo below for the remains). Is this an individually replaceable part? (Hard to see how you could replace it unless it's really stretchy, unless you recrimp the end of the cable). Is this an important part? Is there much of a risk of increased wear (or sticking cable or something) if I don't replace it?
  3. Note that the black plastic, conically-shaped guide that used to be on my A/T kickdown cable is also broken off (you can still see a little fragment of the remains, though). Is this an individually replaceable part? (Again, hard to see how you could replace it without recrimping the end of the cable). Important part, or not? Risky to run without it, or not?
  4. Generally, what is the condition of these guides on your car? The remaining guides on my car look like they're not going to last much longer. Starting to split and disintegrate.



The guide (or whatever it's called) that broke up and came off the accelerator cable end:


One of the "surprise stops". Couldn't just stop anywhere (lots of blind corners, so not wise to stop in street, but no shoulder either). Couldn't just shut down engine, either, because I was going uphill. So, had to time a pull-off, shutdown just right.


Last edited by Ed Scherer; 10-03-2005 at 06:01 PM.
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Old 10-03-2005, 05:52 PM
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Sorry, I don't have any advice for you, but I do have to say kudos for the snazzy animated gif of the problem. Man, you're taking this to a new level. Good luck.

Actually I can add a little advice if you need it - I have a trick for lubing your cables if you want to do that.
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Old 10-03-2005, 06:24 PM
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Originally Posted by Ed Scherer
[list=1][*]Has anyone else experienced a stuck throttle like this? Did it take anything beyond just lubricating the ball/socket connections? Any preferred lube?
I had it happen on a side street, in FIRST GEAR, WHILE FLOORING IT.

Lets say it bounced off the rev limiter in a blink of an eye many times before I got the key off.

A fix? I oiled it, and it didn't happen again.
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Old 10-03-2005, 06:57 PM
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Ed.........from your great animation perhaps your inner accelerator cable is sticking. .....why else would you have that slack on the throttle body cable?

I removed all cables from the plate, lubricated the ball ends with molibdium disulphide (graphite grease) reassembled and adjusted slack per the WSM.

To test any of the cables for sticking after removal from the plate manually move the cable back and forth looking for any binding. If you find any you can buy a cheap device from the local m/cycle store that clamps to the cable end allowing attachment of a spray nozzle tube. Spray the culprit cable first with WD40 or equivalent to get it clean then spray in the cable lube; should also be available at the m/cycle store and you should have good as new cable.

Remember and put a rag at the other cable end if its going inside the car othrewise you end up with a little puddle of mess.
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Old 10-03-2005, 07:00 PM
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Had it happen on my car - after I had mounted the supercharger! It was my fault but still scary!
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Old 10-03-2005, 07:33 PM
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Had it happen to me on a busy main street. Stupid me, I had blipped the throttle to give bystanders some engine music. The engine got stuck in WOT, so I literally shoved the brakes to the floor and pulled over as soon as possible, which was a few blocks away .

Same exact thing: the connector was binding as you've pictured it. I gave it a healthy shot of WD-40 and it never happened again.

I about soiled my shorts on that one, especially when I had to navigate between 2 parked cars on each side of the street with another one coming from the opposite direction. I ended up playing a game of chicken with the oncoming car without the ability to stop . Thankfully they pulled over at the last second and let me through, flipping me the middle finger.
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Old 10-03-2005, 07:42 PM
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On a related question. Is that entire assembly available from one of the Big 3? Mine is not very good looking and I would really like to replace it altogether.

Rob
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Old 10-03-2005, 07:49 PM
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Rob..........the plate assembly can be completely disassembled. Remove the cables and the circlip from the end and all should just pull off. Clean, lubricate reassemble, attach ball ends and reset cable slack. If required lube cables as noted above.
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Old 10-03-2005, 08:34 PM
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I had mine Zinc plated or silver cadmium or something - and I was planning on replacing the bearings. Gosh, I need to do that soon...
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Old 10-03-2005, 09:14 PM
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Originally Posted by sublimate
Sorry, I don't have any advice for you, but I do have to say kudos for the snazzy animated gif of the problem. Man, you're taking this to a new level. Good luck.
Well, it's a hell of lot easier and cleaner to mess with a mouse and keyboard than actually getting my hands greasy doing actual work, isn't it?

Originally Posted by sublimate
Actually I can add a little advice if you need it - I have a trick for lubing your cables if you want to do that.
Do tell!

Originally Posted by BrendanC
I had it happen on a side street, in FIRST GEAR, WHILE FLOORING IT.

Lets say it bounced off the rev limiter in a blink of an eye many times before I got the key off.
I'm not laughing. Honestly.

Originally Posted by BrendanC
A fix? I oiled it, and it didn't happen again.
That's good to hear. I'm hoping that's all that's going on. Mine has been perfectly well behaved since I oiled mine. I'm going to pop off all four sockets, though, clean them with Q-tips, and relube them with whatever is recommended.

I do hate to think about what would happen if someone else (like my wife) was driving at the time. She has only driven the shark two or three times in six years, but this might just keep her from ever driving it again!

Originally Posted by the flyin' scotsman
Ed.........from your great animation perhaps your inner accelerator cable is sticking. .....why else would you have that slack on the throttle body cable?
Interestingly enough, I actually think the cable was in tension, not slack, despite what it looks like. The first time this happened, I thought it was due to exactly that (accelerator cable sticking), because the little conical rubber guide thing was still attached to the accelerator cable at the time, but it was loose, coming apart, and wedged at a weird angle. That's when I actually ripped it off, thinking it was contributing to the problem (it was pretty far gone, anyway). The key thing that I noticed when I finally caught this happening (the third and final time), though, was that the socket on the end of the throttle body cable was clearly stuck and wouldn't rotate down without me forcing it a bit. Then it snapped and dropped back down into its normal position.

Originally Posted by the flyin' scotsman
I removed all cables from the plate, lubricated the ball ends with molibdium disulphide (graphite grease) reassembled and adjusted slack per the WSM.

To test any of the cables for sticking after removal from the plate manually move the cable back and forth looking for any binding. If you find any you can buy a cheap device from the local m/cycle store that clamps to the cable end allowing attachment of a spray nozzle tube. Spray the culprit cable first with WD40 or equivalent to get it clean then spray in the cable lube; should also be available at the m/cycle store and you should have good as new cable.

Remember and put a rag at the other cable end if its going inside the car othrewise you end up with a little puddle of mess.
Molibdium disulphide -- Is that anything like those "Dilithium Crystals" they're always talking about on Star Trek? Hey.... you're not really Scotty, are you?

Seriously, sounds like some good advice, there. I hadn't heard of the cable lubrication device you mention. Sounds like a great idea (one of those things that you think should exist, but you're not sure if it does.) I'll see if I can track one down. Sounds like something I could use for all sorts of stuff (bikes, etc.) Thanks!

Originally Posted by Adam C
Had it happen on my car - after I had mounted the supercharger! It was my fault but still scary!
Holy s***! That thought actually crossed my mind after this happened. The one time I was glad I hadn't done a blower yet! Maybe the installation instructions for the SC kits should include a step for lubing these joints, if they don't already.

Originally Posted by Big Dave
Had it happen to me on a busy main street. Stupid me, I had blipped the throttle to give bystanders some engine music. The engine got stuck in WOT, so I literally shoved the brakes to the floor and pulled over as soon as possible, which was a few blocks away .

Same exact thing: the connector was binding as you've pictured it. I gave it a healthy shot of WD-40 and it never happened again.

I about soiled my shorts on that one, especially when I had to navigate between 2 parked cars on each side of the street with another one coming from the opposite direction. I ended up playing a game of chicken with the oncoming car without the ability to stop . Thankfully they pulled over at the last second and let me through, flipping me the middle finger.
OK, this time I'm really having a hard time suppressing the laughter (I'm farther into my evening beers than earlier in this message). Choice language and puckering involved, I'll bet! At least I didn't have many witnesses when my incidents occurred.
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Old 10-03-2005, 09:19 PM
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Thanks for the replies so far, guys. Still waiting for answers or comments on some of my original questions, though. I'm getting a lot of answers (and entertaining related stories!) to question 1, but nothing on the rest.
  1. Has anyone else experienced a stuck throttle like this? Did it take anything beyond just lubricating the ball/socket connections? Any preferred lube? (keep comments coming on this one, if you'd like, but you've already told me a lot on this one)
  2. Note that the little rubbery, amber-colored, conically-shaped guide that used to be on my accelerator pedal cable split into a few pieces and eventually fell off (see the second photo below for the remains). Is this an individually replaceable part? (Hard to see how you could replace it unless it's really stretchy, unless you recrimp the end of the cable). Is this an important part? Is there much of a risk of increased wear (or sticking cable or something) if I don't replace it?
  3. Note that the black plastic, conically-shaped guide that used to be on my A/T kickdown cable is also broken off (you can still see a little fragment of the remains, though). Is this an individually replaceable part? (Again, hard to see how you could replace it without recrimping the end of the cable). Important part, or not? Risky to run without it, or not?
  4. Generally, what is the condition of these guides on your car? The remaining guides on my car look like they're not going to last much longer. Starting to split and disintegrate.
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Old 10-03-2005, 09:42 PM
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Your throttle stuck open in the mountain twisties?

Some people have all the luck!
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Old 10-03-2005, 09:50 PM
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You think you had it bad?
https://rennlist.com/forums/928-forum/169713-update-on-two-renegade-hybrids.html
Originally Posted by Malibu310
Our Yellow Blower Motor 928 setup (www.rhsdplanning.com/porsche.htm) was in an accident. In my neighborhood at 20 MPH, I blipped the throttle (a quick jab) and the linkage stuck wide open. Since the 550HP and 550 lbs of torque were instant, within the two seconds it took to reach for the key to turn off, we (my wife and I) launched 400 feet sideways through two sets of curbs at a spped I cannot even describe. When we blew through the "dead end" sign which poked a hole in our gas tank, the car did a 180 in less than 25 feet. Amazingly, the only damage was to the tank, a lower right rear control arm, all wheels and tires and some minor body damage, attesting to the strength of the car overall. No one got hurt (another miracle). Some front lawns need to be replaced next spring. It seems the problem was traced (a repeatable problem) to a defective bearing in the throttle linkage. This car will be repaired (with a different linkage setup) within a month, but put up for the winter.
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Old 10-03-2005, 09:54 PM
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Ed: All I have to say is I'm glad you are alive to tell about this!
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Old 10-03-2005, 10:29 PM
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Originally Posted by sublimate
Damn! I forgot about that. After re-reading it, I remembered reading about the incident vaguely, but not the cause.

Originally Posted by Nicole
Ed: All I have to say is I'm glad you are alive to tell about this!
Forget about me, it's the car that matters. It's still alive and well.

Throttle cables have been lubricated.

And tonight, in order to maintain the perfect balance between car and driver, I have also been lubricated -- with some DAB (Dortmunder Actien - Brauerei) and Paulaner Oktoberfest Mńrzen. And Paulaner is the best brewery in the world.
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