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Black 560 SEC AMG, White 560 SEC Carat (RIP 09) , 300E
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1,296 Posts
Discussion Starter · #1 ·
hi guys i was wondering if i have a problem with my throttle pedal, there's no response until the pedal's been depressed least 3 to 4 cm. A mate of mine had a drive tonight and thought the trottle have a rather large 'deadzone' and felt very stiff? it feels like that since day one so i don't notice...
 

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1987 & 1991 C126
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6,449 Posts
Hi there,

My car had the exact same thing when I first got it, about an inch of free play in the linkage before the engine would accellerate. I also found the car was not getting full throttle as well.

After consulting the MB CDs, removing the aircleaner and measuring all the linkages, I had my wife put the accel pedal down till it was just touching the kickdown switch - no further. Obviously the engine has yet to be started here.

I found I could push link 5 further down.. opening the throttle.

With my wife still holding the pedal in position, I loosened the adjustment at 4 on the shaft between the firewall & just inside the left valve cover. Pressing link 5 all the way down (Wide Open), I tightened the adjustment nut 4 up at the firewall. My wife then released the throttle and retested for full travel. After another go at the adjustment it was all set.

After the adjustment, I made sure the roller at 15 & 13 was free and the linkage didn't bind, the engine was started and checked for good idle & throttle response. All OK.

After lubing the linkage & reinstalling the aircleaner, I took the car out for the road test.......

What a HUGE difference! I wish there were less houses around where I live, as the car was/is significantly more powerful and has instant throttle response. Been that way for two years now.

A while back, Mike Ramay shared info from an MB tech meeting, which recommends replacement of the 19 link with a corresponding item from an R107. I haven't felt the need for this modification, as my car gets full throttle and has good throttle response with the stock setup.

Mike's post: http://www.mbnz.org/forums/forums/thread-view.asp?tid=1228392&start=1&fid=12

Whatever you do, it will be quite a difference! [:D][:D]

Hope this helps. MBL
 

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1987 & 1991 C126
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Glad it made sense..

My car had some repairs to that throttle linkage in early 1988. The previous owner always had remarked to his business partner over the years that the 560, although nice and smooth, never quite had the punch that their 300 did!

I'm pretty sure the car only got 70% full throttle from February, '88 till May of 2004 (67,000 break-in miles). His business partner drove my 560 in late 2004..Said it was an entirely different car. [:)]

I'll bet that picklesam's car will 'come alive' too!
With that much play early on, as he describes, there is no way that engine can go Wide Open Throttle.

Cheers, MBL
 

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1992 W126 300 SE
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11,045 Posts
My 928 had too much free play in the throttle linkage when I got it and the adjustment made a huge difference to the response.I wonder how common is this problem? I haven't even looked at my 126.
 

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85 euro 500sec 91 420 sel
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138 Posts
i was told that that "dead zone" was due to k-jet fuel injection as it is a linear response, after a few months i got used to it, but car has great power.
 

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1991 300 SE
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18,534 Posts
With mechanical fuel injection like K/E Jetronic/CIS – E engine speed is increased by increasing airflow rather the fuel flow as with EFI; this combined with the design of the throttle linkage results in the ‘heavy throttle’ effect. Diesels also have mechanical fuel injection and experience a similar effect.

My g/f’s car is EFI (I need to get her a Benz…) and when I drive it I always manage to chirp the tires when I mash the throttle.
 

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1987 & 1991 C126
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6,449 Posts
As I have just learned that picklesam's car has ASR, and that it appears to be malfunctioning (ASR light ON), I hasten to amend this thread with: The throttle linkage adjustment guidelines I previously posted are for cars without ASR.

The procedures used when adjusting linkages on vehicle with ASR I have no practical 'hands on' experience with.

I do know (from the MB CDs) it is possible to damage linkage components if one doesn't know what they are up to and tweaks the wrong thing.

Regards, MBL

The 'Heavy Trottle' may be a side issue regarding the malfunctioning ASR.
 

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1987 & 1991 C126
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6,449 Posts
OK All, so here is the deal:

The reason the throttle is so heavy is the fact that the ASR has a problem, and picklesam is accelerating via an "Emegency Driving Facility" which uses the spring loaded Idle Travel Rod to actuate the throttle valve, instead of a servo motor doing so, as is normal.

Additionally, you will notice in the copy (from the MB CDs), that only "2/3 of available engine output can be utilized" under this back up scenario.

Picklesam, I'd get this one looked at by a trusted MB specialist with grey hair... not some young tech who knows everything, but without real practical W126 experience.

My 0.02USD/0.03AUD....

Cheers, MBL
 

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'82 380 SL, '82 300TD, '85 500SEC
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194 Posts
This is a follow-up question primarily for MBL87560SEC, but everyone's invited to comment. He said [After the adjustment, I made sure the roller at 15 & 13 was free and the linkage didn't bind]. I'm working on the same deadzone issue and when I watch the "roller" he refers to in my case it has to begin travel and probably moves perhaps 5-7+ mm within it's little opening BEFORE the linkage ending at #5 even moves. I suspect this is my deadzone issue, but MBL87560SEC's post seems to suggest the movement at #5 is immediate after the pedal is pressed. Am I seeing things or is there an adjustmenmt I messed up (on my '85 500 SEC)? Thanks.
 

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1987 & 1991 C126
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Hi There, linkage lovers,

I think I left out something / got the sequence wrong. So... sorry for any confusion.

Dave is, of course, correct regarding the roller movement.

This roller is supposed to be 'free' with a link temporarily removed, and is part of the base setting of the linkage, making sure nothing is binding and the car achieves a closed throttle state, done before the wide open throttle check & adjustment.

Here's the copy from the CDs. I hope it doesn't make me look too, too bad!

See if this makes more sense.
 

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'82 380 SL, '82 300TD, '85 500SEC
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To MBL87560SEC, I was not trying to out-detail you, I just wondered if there was a trick you knew that I didn't. Anyway...are you saying that the little roller moving in its arc does not create the deadzone? Or it is not noticed in the driver's seat? I suppose I am more used to direct linkage that actuates as soon as the pedal is pressed...and if it doesn't...I'm all over it. Just curious, when you adjusted the linkage to the best case, is #5 supposed to wait til the roller does it's thing? Thanks for all the pictorials...they help a lot. Dave
 

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Black 560 SEC AMG, White 560 SEC Carat (RIP 09) , 300E
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Discussion Starter · #15 ·
you're a star MBL! thanks!Gee i can't believe i haven't experienced my car's full power, better get a mech to come around. i always thought if the asr comes on it means it's disabled! how embarassing haha...nice sec you got there by the way MBL!
 

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1991 420 SEL
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949 Posts
I adjusted #4 based on MBL87560SEC's post

wow what a difference ... I can feel much more power...
and the response is very quick from the pedal...

my fuel consumption will probably go up as well

[:D][:D]
 

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1985 500 SEC, 2005 E320
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1,294 Posts
there is also a plastic bushing in the linkage that goes bad on some if not all Mb Models of the era. Don't quote me on that, I know the SEC well and that was the first thing I replaced on this car when I got it. It was totally missing. I had to replace 3 of em on various MB's I've had.
It has a tendancy to break apart and you don't even notice it's missing unless you know what to look for. That will account for about 1/2 of the pedal travel. At least in my experience it has.
 

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1985 500 SEC, 2005 E320
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I'll take one tomorrow for ya. Bringing it into my shop for another look at the exhaust, brake squeek, plugs, cap, rotor, and to assess a power steering leak. so when I got the air filter off, I'll snap some pics of it for ya. Speaking of which, I forgot where I saw it, but someone on this forum had an air filter that had 2 intake pipes coming off the air filter, one on each side. Who was it, and was it custom? and if it was custom, are the pipes still available? mine is broken in 2 spots. got duct tape holding it together for now.
 

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1982 280 se aut. ecc. - sold
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1,607 Posts
Kingorcus said:
I adjusted #4 based on MBL87560SEC's post

wow what a difference ... I can feel much more power...
and the response is very quick from the pedal...

my fuel consumption will probably go up as well

[:D][:D]
every cloud...........:D :D

gr J
 
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