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Sir Spence

F10 N55 revs dropping on a constant throttle on cold start

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My manual N55 N10 has as ongoing issue in that it's hard to drive off smoothly after a cold start. It's fine once warm and in the recent cold weather where I had to de-ice for 5 mins, that was also enough to get past the problem


I've done some investigation over the past couple of days


Sitting in neutral (manual) and applying enough throttle to see 1500rpm come up, it will almost immediately drop to around 600rpm 

It will then stay at 600rpm until I lift off the throttle

Applying throttle anew, I get the same issue 

..and repeats for 2-3 minutes, after which the revs will drop and then creep back up


With a warm engine, I still get a drop in revs (albeit smaller) on a constant throttle if I go to somewhere no higher than 1500 rpm

If I raise the revs to 2000rpm, it seems to hold steady


No codes are being thrown and I've tried the throttle body reset (turn on electrical power, pin the throttle for 5 sec, switch off and wait 2 mins and it's not fixed it


Low Pressure Fuel Pump was replaced 2 years ago after it threw an error on start up with engine warning lights and associated codes


I'm conscious that without codes being thrown, it's a crap shoot taking it in for a diagnostic, so any suggestions?




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12 hours ago, Sir Spence said:

Thanks for the reply @Andrew - I’m just looking for codes in the unlocked binnacle menu at the mo, but I’d like to keep the car for a while (55k on a 2010 plate) so up for getting a reader..?


You need to read the codes via the OBD port using ISTA and an ENET cable. The instrument cluster codes only pertain to the iDrive or cluster and not from the many ecus in the car. I’ve been using ISTA for years and as it is dealer level software it’s your best place to go. There are other code readers out there too. 

Edited by Matthew Ashton

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Right, apologies for carpet bombing here, but I don't really know what I'm looking at


I've used the Bimmerlink App and a TONWON wifi port


Nothing came up at all under permanent errors, but I got the attached under various other menus.


To the untrained eye, this looks like a load of detritus, but I'm sharing in case one of you fine folks can find an/the issue / issues?


Any help much appreciated!














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Been doing a little code searching - the site I ended up on didn't have every code and became a PITA asking for Captur all the time, but I did get the following from it, although the first to were not listed specifically for the N55


100601 - Throttle body actuation

100100 Throttle body actuation


This one was listed for the N55

100001 Throttle valve function briefly clamped


The suggestion for this last one was that the throttle body actuator was what was throwing the code?


So in the real world, what does this mean and what do I do about it?







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I had similar hesitation/stumbling with 6cyl 528i. I could get it to throw a fault by starting the engine cold and letting it idle for a few minutes without touching the gas at all. It would start misfiring and throw an error code eventually.


Dealer had it a few times and the eventual fix was to replace all 6 injectors to the tune of €1200 (under warranty thankfully).

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If you are able to get someone with ISTA on a laptop and use that for diagnosis as it gives you the miles the specific code was triggered so you can see whether it is an old historic code or something more recent. It also translates the code into BMW speak and will go through a diagnosis plan for each specific code so you can drill down into the module throwing the error. 

Edited by Matthew Ashton

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