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Discussion Starter · #1 ·
My lovely little car has been sitting for 6 months because of an ignition problem. I have other cars to drive so it sat patiently waiting. Yesterday I decided to get her going, she was misfiring on #2. I swapped coils between 1 and 2 and the misfire went to #1. So bad coil, no big deal, I pulled one from my 330Ci and now she's running again, yea! I've put maybe 50 miles on it since yesterday. Today I went to the local apple orchard for opening day because they have the best apple cider donuts. On the way home I stopped at a stop sign, when I went go I heard a pop/snap as I pressed on the gas pedal and nothing. After further troubleshooting it appears as thought the cable has popped off the throttle body. I can move the gas pedal and the cable moves so it is not a broken cable. That throttle body is certainly buried down there! I have removed a lot of the ducting leading up to the throttle body and can sort of see it but not very well. Is there a common failure item here? Like something made of plastic perhaps?
 

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what car is this? Maybe a '99- '00 528i ?

EDIT: I see from your previous posts it's a '99 528iT. Yes this is not uncommon. The throttle cable is pretty fiddly in there. Unless the cable or part of the throttle body broke, you should still have the little ball on the end of the cable and it can be re-attached.

Make sure the rubber grommet is still in the bracket that holds the adjuster wheel...Many M52tu cars have this rubber grommet disintegrate.
 

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Discussion Starter · #3 ·
Yes the 1999 528iT. So the cable still has the little ball attached and the mounting bracket has all rubber intact. See the picture below. When I look up throttle cable for that car I do not see a picture identical to mine, they all seem to have some different hook on the end? That is rather confusing. So, if the ball will still connect to the throttle body, do you suppose there was just too much slop (like misadjusted?) and just happed to pop off? I saw some plastic piece on Pelicanparts that was a throttle linkage part but not sure where it was used??

It would be helpful to be able to see what I am dealing with, maybe a mirror would help. I tried my phone but that was of no hep.
 

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Inspect the spring loaded wheel of the throttle body where ball and cable attach..I've seen this part break and allow the cable to slip off. If nothing is broken, yes, some slack in the cable may have caused it. HOWEVER, read up on adjusting the MDK (throttle body) cable for an M52TU..and do not just start cranking on that adjuster knob... That whole Throttle Body arrangement - which is a hybrid drive by wire/drive by cable thing - is extremely sensitive to changes in cable tension...This is one reason my '99 528i - which is my first BWM and which I bought in '03 - is in storage at the moment
 

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Discussion Starter · #7 ·
I have never even looked at that connection before, since it has never been a problem! I would suspect that the cable adjustment nut would be adjusted so there is minimal slack at idle. I was able to guide the ball back into the throttle body lever and it stayed there, but I did not push the cable mount back into the bracket because I did not have light. I will tackle it tomorrow with fresh eyes. I am happy to know that it is close to being back together, I love driving that car!
 

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Wingnut
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the cruise control works just like the DSC does, varying the throttle plate position to need. the MDK in 99 and 2000 is a hybrid system, in between the early mechanical linkage and the later fly by wire no mechanical systems. whne one presses on the throttle pedal, it sends a "drivers wish" signal via the cable, however the actual position is set by the motor in the throttle body, which is overridden if needed by the DSC or cruise.
 

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Discussion Starter · #9 ·
I cannot get that cable with the little ball on the end to latch into anything on that throttle assembly. It would help if I could see what I am trying to accomplish, but I can't see it at all so I am going by feel. It feels like I get into into a recess after I have rotated it up, but as soon as I slowly let it retract the ball pops out. Does the ball maybe slide in from the side? I wish I had a picture of what I was trying to hit. I have searched the web but found nothing helpful. I am not giving up on this.
 

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Discussion Starter · #10 ·
I held the throttle mechanism o pen with a string so I could get a mirror down there and I can see where the ball goes it. It's hard to see any detail of that recess, like is it worn out allowing and not holding the ball? If you blow the picture up you may be able to see that in the little mirror. This is a great example of why we should have borescope's! I can easily justify spending money on tools.

Automotive fuel system Motor vehicle Automotive design Automotive exterior Auto part
 

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Wingnut
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trying to think of a good way to describe this...if you look at where the socket on the linkage retains the ball at the end of the cable, the cable must be held at an angle that allows the ball to pop in the socket and the cable perpendicular to allow it to drop in to the slot in the socket (iirc i had the cable adjuster loosened all the way and had the cable removed from it). the cable then needs to be put in to its slot that follows around the linkage, then the cable remounted and adjusted. i hope i described correctly.
 

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Discussion Starter · #12 ·
So, I took the string off and allowed it to close, then worked the ball end up to where I thought it should be and the pushed the threaded adjuster into it's bushing and as soon as I let my finger off the ball end it pops back out due to lack of tension. If I pull up on the cable it will stay in. I cannot get enough tension on it for it to stay regardless of where the adjuster is adjusted. So I am wondering, did somethinh happen at the other end of the cable where it meets the pedal? I know the cable retracts when the pedal is pressed.
 

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You need a new throttle cable, the sheathing is gone, should not be rust colored like in the picture. When I replaced my throttle cable on my 2000 528i (old cable looked as yours does in the picture), getting the new cable ball seated was difficult. I have taken my throttle body out enough times to understand how the cable fits and I still had difficulties getting the new one on there and seated correctly.
 

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It is certainly possible that the spring-loaded, plastic actuator on the throttle body that holds the ball end of the cable has cracked and will no longer hold the ball..I have seen it before.

Take a look at pictures on M52TU throttle body to familiarize yourself.

You can remove the throttle body and determine for certain. It has four bolts. You might replace it's gasket while it is out...

Be careful when handling this 22-year old throttle body...Treat it like a mechanical computer hard drive full of old family photos. Back in the day, dealer tech's avoided removing it as it is quite sensitive.

The round 10-pin connector with rotating closure is a little tricky...easy to remove, rotate it away from you, then remove plug..But to reinstall...you need to rotate away until it clicks, insert onto throttle body then rotate towards you until it clicks.

To make you aware, there are many reported problems with the M52tu throttle body (aka MDK), just not the one you are reporting.. A common problem relates to corrosion getting into the wires/connectors of unprotected 10-pin connector, and causing minute changes in electrical signals to/from the Throttle body and putting the car in limp mode.

Here is one guy's solution.
MDK Repair
 

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Discussion Starter · #15 ·
Thanks for the tips, I had not thought about the cable being bad. As I was laying in bed just waking this morning I was thinking about the thing and it occurred to me that I was reinstalling the cable wrong on the bracket with the rubber gasket. I was installing it with the adjuster UNDER the bottom of that bracket. I remember now pulling the cable right straight up and out of that bracket after it first came loose. I will tri it the CORRECT way and order a cable also. I was hoping to get a look at a throttle body to what that spot looks like where the ball seats. Mine does not snap in at all.
 

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Discussion Starter · #16 ·
I just looked at some M52TU throttle body pictures and videos but did not see in detail where the little ball connects. And I must say WOW, that is one complex throttle body! What could go wrong? And they were only used for 2 years? How much disassembly is required to get to that throttle body if I need to replace it? On one of the videos there was an explanation of how the creature works, quite impressive!
 

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Discussion Starter · #17 ·
After realized my mix-up I got the cable back on and if feels secure. I pushed the ball end in and tried to slide the cable into the grommet/bracket and had no luck at that so I ended up pulling the grommet from the bracket, putting the grommet onto the cable then slipping the grommet w/cable onto the bracket. I think I have the adjuster screwed out a little more than what it was originally. I have not had it out for a drive yet but I have all the bits-n-pieces back in. I oiled the rusty throttle cable for the time being and will order a new one post haste.
 

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Discussion Starter · #18 ·
Test drive was a success! I did not stray too far from home, I experienced not odd symptons and I do not have the CEL lit so I will call it good for the moment and order that new throttle cable.

Thank you all for your helpful words and guidance, that is what makes these forums so special. Tom
 

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Wingnut
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well done..when ordering the new cable, there is a rubber bushing on the throttle pedal that the cable hooks in to...they wear, and can put a bit of slack in to the cable. theyre a a bit of a bear to replace, but worth doing.
 

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Discussion Starter · #20 ·
Thanks, I already ordering the cable from FCP. I compared prices/delivery between FCP and Pelican and I do recall seeing some associated parts, most likely that bushing, at one or both of the sites. I did not check my local dealer but having the part number in hand I will call and just see what they might charge. Always good to shop around. I buy a lot of car parts from NAPA and they had nothing for this application.
 
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