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1976 450 Lorinser SL
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21 Posts
Discussion Starter · #1 ·
HELP!!

I need help resolving my sticky throttle issue that is only sticky when the engine is running. I have full free travel when the engine is off. But after I start it, it holds whatever RPM I accelerate the engine too. I have to put my foot behind the gas pedal and pull it back in order to return the engine to idle. I played around with disconnecting the throttle linkages and I isolated it to the very end where the linkage rotates down to what I assume is the actual throttle body just foward of the air intake opening. Any chance it's a vacuum related issue?

Any ideas? :confused:

Chris
 

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1984 380SL
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2,374 Posts
Do you have cruise control? (I do not.) That uses vacuum. I think it hooks in where the rods take the downward plunge in the front as you describe. Otherwise, the return spring is located behind the blower box.
 

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Premium Member
1975 450SL
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2,440 Posts
If the linkage is binding, look for places that change when running as opposed to not. There are two ball bushings on the linkage, one at the firewall and another on the manifold, that may be binding if your system is like mine.

Another possibility is that the motor mounts may be collapsed enough to bind the linkage.

You may get lucky and be able to fix the problem by going through the linkage and checking and/or lubricating.

Just a couple of Wild guesses.

Scott
 

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22,841 Posts
.

mortis said:
I need help resolving my sticky throttle issue that is only sticky when the engine is running.

I think this is critical.

Is there anything in the "pedal linkage connected to the throttle plate connected to the air meter plate connected to the fuel distributor piston" continuum that could could cause this?
 

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1976 450 Lorinser SL
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21 Posts
Discussion Starter · #7 · (Edited)
Going down the road that this might be a vacuum related problem. I see a vacuum connection on the front passenger side of the engine that has no tubes connected to it. In fact, one of the nozzles is broken an plugged with silicon by a previous owner and the second is just disconnected. In the attached photo of a new engine I circled it in red. Can someone tell me what those tubes lead to? And could that be related to my throttle problem?

Chris
 

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2010 Mercury Milan Hybrid, 1993 BMW 325i convertible
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6,077 Posts
In the attached photo of a new engine I circled it in red. Can someone tell me what those tubes lead to? And could that be related to my throttle problem?
If you give me a decent sized picture, probably.
 

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1976 450 Lorinser SL
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21 Posts
Discussion Starter · #9 ·
Finally, got the car out today! I still had the same throttle issue but I think I have more info for trouble shooting. I noticed that a quick goosing of the throttle would cause the engine to return to idle. This happened both when then engine was both cold and warm. Chatting with a local mechanic mentioned that it sounded like a choke issue. I didn't think this car had a choke give it's fuel injected. Some googling brought up topics on Aux Air Valve and more vacuum leak issues. Does this sound about right? I'm guessing I may need to start replacing all of my vacuum hoses...
 

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'80 450SLC Afro RHD Ikonengold
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3,195 Posts
linkage bushing tend to fail, it may stick.

I think there was a recall on that. Go trough sticky EGv107
 
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