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I just bought an 89 S4. Was driving it home last night and stepped on the accelerator and the car kicked down from 2nd to 1st. When I needed to slow down I noticed that the car seemed to still be accelerating. Lifting off the brake it pulled forward at wide open throttle. Surprised, I hit the brake and it slowed down but was still pushing forward. I put the car into neutral motor revved to red line and I put it back in gear and turned it off at the ignition. Read a little about sticky throttle cables etc. anyone know a good video that explains disassembly and diagnosis of throttle on an S4?
wow........thats a very bad introduction to your new car.
You mentioned the transmission kicked down so shall assume its an auto gearbox. There are 4 cables on the quadrant for the throttle operation; quadrant to pedal, quadrant to throttle plate, quadrant to gearbox, quadrant to cruise control.
I take all 4 off the quadrant then test them all espeially the throttle plate cable and pedal. If your unsure which is which take the air box off and follow them.
If the cables appear ok then its very possible the throttle plate mechanism itself which is located under the intake. If you have the skills to go this far Id recommend following Dwaynes intake epic.
What ever you do, do not drive the car until fixed.
I just bought an 89 S4. Was driving it home last night and stepped on the accelerator and the car kicked down from 2nd to 1st. When I needed to slow down I noticed that the car seemed to still be accelerating. Lifting off the brake it pulled forward at wide open throttle. Surprised, I hit the brake and it slowed down but was still pushing forward. I put the car into neutral motor revved to red line and I put it back in gear and turned it off at the ignition. Read a little about sticky throttle cables etc. anyone know a good video that explains disassembly and diagnosis of throttle on an S4?
99% of the time, the problem as you described it, is caused by the cruise control cable.
The plastic ears that keep it captive break off, which allows the housing to pop out of the throttle quadrant, which keeps the throttle open.
Simply push the cruise control cable housing back into the quadrant. Use a couple of tie wraps to hold the plastic housing in place (the cable is NLA.)
99% of the time, the problem as you described it, is caused by the cruise control cable.
The plastic ears that keep it captive break off, which allows the housing to pop out of the throttle quadrant, which keeps the throttle open.
Simply push the cruise control cable housing back into the quadrant. Use a couple of tie wraps to hold the plastic housing in place (the cable is NLA.)
Anyone have a pic of this?
After refreshing my intake on my '79, I had a hanging throttle too - wasn't like the OPs though it would only hang at about 2,000 RPM. I checked the floor mats to make sure they weren't the cause and manually opened and closed the throttle plate where the cables attach - didn't look like it was closing fully from the little bit of tension that remained on the cable. If I would put my foot under the gas pedal and lift it up, the car would return to the normal idle.
When I refreshed my intake, I actually cleaned the inside of the throttle body and removed quite a bit of black gunk from around the edge inside edge. My assumption after the hanging throttle occured was that the gunk was actually making a seal between the throttle plate that moves with the accelerator pedal and cable, and the inside of the throttle body. Without the gunk, fuel and air were leaking past the plate and causing the increased RPM hang. I also thought maybe the return spring that closes the throttle plate when lifting off the pedal had become weak. My solution was to add a little helper spring to the bottom unused ball attachment point of the linkage (maybe it is supposed to be used and I'm just missing something) and attach it back to the a small hole I drilled in the opposing bracket that holds the cable. With the helper spring, the car runs better than it ever has with the RPMs dropping back to about 800 very quickly and no more elevated RPM during shifts or when sitting at a light. The helper spring is quite weak and you can't actually tell it's there when operating the pedal, based on effort. Having seen this post about the cruise control cable though, I'd like to check into that as well, which is why I'd like to see a picture.
well that would deeply annoy me. along time ago I had a tripower linkage hang up on decelleration. took me a few feet, heading into a curve to remember to turn off the key. sweaty armpits?
Turns out it was something simple. Seems like part of the linkage got caught up. I will share with you a better explanation when I get it back from the shop.
Thread revival. This happened to me yesterday in my red 1985. The good news, the intake refresh and everything else I did worked great. The cars runs very well. The bad news is I just about **** myself - passed a car on a 2 lane, down shifted, hit the gas hard, then like a rocket the engine was bouncing off the rev limiter and I was uncontrollably accelerating. Fortunately, nobody was in front of me. I was able to shift to neutral, pull over and cut the ignition. Didn't know what to think, other than wow. After my nerves calmed down, I fired it up, turned around and carefully drove home without further incident.
So, where is the cruise control cable on the butterfly swivel at the front of the engine (not sure what to call that part - it has the ***** on it for the throttle linkages). I have 2 cables coming in - one has a rubber bellows on it. One cable is for the gas pedal and the other must be cruise control? Not sure which is which. I think one of these cables is getting hung up. Also, from the pictures below (taken from a post of an S4 which has a different configuration but is close to mine) you can see amber colored cable guides at the end of the cables. On one of my cables, the brittle guide had broken off during my intake refresh. Could this be causing the problem - not having the guide? also, how do you lubricate these cables?
Note - the problem is not the throttle rod to the throttle body. I actually had that issue last week - the rod popped off because it was hitting a hose. The throttle body itself is fine as well. My current problem is with the cables I beleive, but pictures would be good of what Greg is describing above, so I can check that too.
Finally - problem solved. The rubber kick plate inside the cabin was the problem. The gas pedal kept getting hung up on it. Damn, and I never touched the inside of the car. My buddy came over and we felt the pedal acting like it was hitting a kick down switch, which as a 5 speed, we know there is no kick down switch. I thought I might have to open up that damn pipe organ again too, which I hate doing that job. We'd hear the noise, feel the "catch" and I finally climbed in and examined the gas pedal. I felt the interference with the rubber plate. Pulled it off, the catch sound and feel completely disappeared, and we went for a nice long and very spirited drive. Car - finally - runs great!
The offending part (I'm guessing the last person who had it out didn't put it back in right):
03-13-2016, 12:14 PM
Stuck throttle
