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Discussion Starter · #1 ·
Hi I have a 525 SE Auto 1990 low milage. Can any one throw light in the type of Throttle position sensor that i have on my car and how to set it up from scratch .It has a round connector (unlike most pictures in manules - oblong showing three spade terminals) with a number of pins which look as though they are laid out in pairs it is about one and a half inches in dia. and when pushed in has a secureing clip that is pressed over to insure that it cannot fall out. My car does not have a cold start valve an oxygeon sensor in the exhaust or an extra screw on the throttle body appart from the throttle lever stopscrew. it has the large round plug on the nearside that accepts an electronic readout tool which i believe is of 20 pins however looking at mine it only has about eight or nine of these holes holding a femail socket . All this considered can a recognition be made as to what series of Motronic it is . My local BMW garage ( not dealer) says very little info would be available from this plug and the cost of having a diagnoses done is not worth while. Problem jumpy tickove ..I have changed the blue temp. sender with a slight inprovement shown, no holes in any of the rubber breather pipes, tappets ok plugs ok, Air flow sensor tests ok ( note no aditional mixture screw for tickover here)
 

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The TPS is shown as item 2 in http://bmwfans.info/original/E34/Lim/525i-M50/ECE/R/A/1992/05/mg-13/ill-13_0368/

There are 2 different parts depending on if you have ASC+T fitted, or not...

You shouldn't need to set it up at all...simply screw a new one on and Robert is your mother's brother! They do wear and give false readings...Usual symptom is a slow return to idle after lifting off the throttle (usually sticks at around 1000-1200rpm slowly returning to normal idle).

If the idle is lumpy or erratic and you're sure there are no air leaks between the MAF and the cylinder head, then maybe worth cleaning the ICV (idle control valve)

That is item 6 in http://bmwfans.info/original/E34/Lim/525i-M50/ECE/R/A/1992/05/mg-13/ill-13_0381/

A good swill with petrol or carb cleaner should help if it is sticky...If it is really shot, though, it will need replacement.
 
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Discussion Starter · #4 ·
It only has one throttle position sensor and this situated under the housing that contains the butterfly valve and is operated by the butterfly valve shaft .I am not sure what ASC+T is, if it is automatic stability conrtol the answer is no. The switch in question seems to be more of a potentiometer than a series of switches and it is held in position by two phillips head screws and can be adjusted by turning the switch within the range of its elongated holes. At the moment i have it adjusted so that the butterfly valve is very slightly open ie. 02mm and the switch positioned so that an audible click can be heard instantly the butterfly valve is opened further.You mentioned air leaks ,i have very carefully checked the hoses in question but i have found a further possible fault since posting my problem . There is a sucking sound that i have always assumed to be the normal sound of the engine however i have traced this soumd to just in front of the rear inlet manifold bolt using a short length of garden hose to the ear, all looks ok but i decieded to apply a little oil arround this area and lo-and behold it produced smoke from the exhaust. I have now ordered a new manifold gasget and a set of injector seals, i am keeping my fingers crossed that there is no problem with the manifold itself. I still need identification of the valve and the recomended way to adjust it.
 
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