W140 ETAs dont open throttlebody fully?

[Christian_K]

I bought a W140 ETA/Throttelbody of Ebay from Year 2001. It works good in terms of that its not throwing any codes, as opposed to my Stock 1992 W124 500E unit which has sometimess 2-3 faault codes with Potentiometer overwatch/oversight and a safety contact switch, however NO limp mode with my old TB.

Please see the video:
[video=youtube;wluNngK-OuE]https://www.youtube.com/watch?v=wluNngK-OuE[/video]

Victor from Restoreyourmercedes also shows this on one of his W140 repaired TBs:
[video=youtube;Ci8fz62O8ew]https://www.youtube.com/watch?v=Ci8fz62O8ew[/video]

Question would be if that is the case the way we are trying these units, depressing the gas pedal with a heavy piece of something and then operating the ETA.
Maybe it has to be done simultaneously, like when done by the linkage cable?
I think about returning the unit as i cant stand it to loose Power.

 

[gsxr]

They should all open the same amount. The W140 ETA won't open any less. What does your old/stock unit do when connected as seen in your video?

 

[Klink]

That is as far as they are going to open without increasing engine RPM being detected. Note that the movement in both videos is approximately the same. The unit in each of those videos is functioning normally. You only need to have the gas pedal depressed enough to change the value of the switch S29/3. If the unit does not throw fault codes or go into limp mode when operated as in your video, it is probably fine.

Possibly related, and for what it's worth, almost all electronic throttle controls include some functionality to maintain air velocity. Very seldom if ever does one actually get a full throttle valve opening with any electronic throttle control until very high air masses and/or RPM are detected.

 

[Christian_K]

Thanks for your replies. I cant test my old 1992 TB this way yet as its still in the car and runs "fine", besides some error codes sometimes. But no Limp mode at all. Car runs very strong.
When i remove my Airfilterbox and look down the MAF with a light, someone is in the car with ignition on and depresses the pedal all the way down the Full-throttle position, my old TB opens fully 90°

Klink, the S29/3 only "knows" two positions or values, a) a certain Resistance for the idle position of the pedal and b) an infinite value for a non-idle position of a depressed pedal.
So my method of not triggering a limp mode is to start ignition, throw a heavy piece on the gas pedal so its depressed (does not matter how far!) and then i can electronically operate the ETA like in the two videos.
However this will always trigger an error code with the S29/3 involved. So IF, like you both stated, the W140 TB opens fully under normal conditions, i think its because the S29/3 behind the pedal and the idle switches inside the ETA are not switched simultaneously with my test method.

So i'll keep that unit and throw it in when i replace heads next month.

 

[Klink]

Most interesting, Christian. Just for my curiosity, what part number is on your old throttle body (the one that opens to 90 degrees)? How far does it open when the key is off?

 

[Christian_K]

Most interesting, Christian. Just for my curiosity, what part number is on your old throttle body (the one that opens to 90 degrees)? How far does it open when the key is off?

Part Nr, i dont know yet. Will see it when i dissassemble it, but its the stock 1992 500E TB for sure. Without ignition on, i can only open the blade it like when in limp mode and totally let say 50-60% ?

 

[J-Sauce]

When you say "ignition on", does that mean engine running or key in run position with engine off? The throttle butterfly should not open to full 90* until the engine is on, and pedal is depressed to bring revs up.

 

[Christian_K]

When you say "ignition on", does that mean engine running or key in run position with engine off? The throttle butterfly should not open to full 90* until the engine is on, and pedal is depressed to bring revs up.

Yes i mean with engine off and key in the ignition-on position. Is that differently named in the USA?
My Throttle does in fact open to 90° or a 100% with ignition on on my 500E.

 

[Klink]

Yes i mean with engine off and key in the ignition-on position. Is that differently named in the USA?
My Throttle does in fact open to 90° or a 100% with ignition on on my 500E.

We are meaning the same things. It is actually the behavior of your original throttle body that is most unusual...