EDITED original post below. It seems at this point that the issue has been pinpointed to the differential which was replaced. Although the shop says they ordered a manual transmission dif, and their paperwork confirms this, there is an automatic dif (3.15 final gear) instead of a manual dif (2.81 final gear) in my manual car. I confirmed the ratio after watching this video. The short of it is spinning one wheel 10 times while the other is held (in an open dif) while counting the number of times the drive shaft revolves. Multiply that number by 2 then move the decimal left one place (essentially dividing by 10). In my case, backed up onto ramps then carefully raised one side and supported on jack stand. marked the tire and driveshaft with chalk pen and had my girlfriend rotate the tire while I counted (both counting in our heads). 15.75 turns of the driveshaft X2 = 31.5, when you divide that by 10 you get 3.15. The exact ratio suspected in this case.
The symptoms for this problem are cruise control that activates but will not hold speed well, especially over bumps, down hills, or when you press decel. It sometimes will not engage unless you are "helping it" by already accelerating while holding accel. However the cruise works perfectly for me in a lower 4th gear (mistakenly diagnosed by me as lower speeds). It also works more reliably above 80mph.
I am still trying to solve this problem as many people have had it and said the solution is to reprogram the DME but I haven't gotten more detail than that. I hope this revised info helps someone else in the future, I suspect this problem is true for anyone who has swapped diffs to a lower gear ratio. END EDIT*
Hello all! First post here, of perhaps very many considering this car. Did some searching and couldn't find anything specific to my symptoms. Been driving this car for several years now without any major drama, mostly just maintenance. The car recently sat for about 7 months after a dif failure. Since I've been sitting on my ass during the pandemic I was finally able to find a good low mileage unit and have a shop I trust install it without breaking my limited bank. Since getting the car back it has a somewhat intermittent cruise problem, I'll switch to list mode to try and make it easier to understand.
-Cruise control turns on and light will stay on no problem even when CC isn't engaging. Sometimes it will engage with no problem and cut out later, other times it will just barely start to engage before cutting out. It SEEMS to happen more often when the car needs to keep from accelerating to maintain desired speed.
-2000 540i 6 speed with nearly 250k miles. Cruise has always worked smoothly until now.
-Originally thought it was voltage related, found out I had a SECOND bad alternator soon after dif replacement. (it has been a rough 2 months). Now alternator is fixed and cruise is still not working.
-Car is throttle by wire with all buttons for CC on steering wheel, to me this eliminates many possible failure points.
-Only other warning light is SES for air injection system (I suspect clogged ports) and codes that havent cleared from storage yet for an unhooked coolant sensor after the alternator was put in. This also seems to eliminate many failure points (abs) to me
-Visually, functionally checked brake and clutch switches, both seem to be working, brake lights work fine.
-I just got a creator 310+ but it seems many things give me a communication error, I can check and clear codes, see live data and ecu info, and even clear throttle whatchacallit. but it wont let me look at any of the sub systems. user error?
Any help would be much appreciated. I hope this long ass post makes sense!
The symptoms for this problem are cruise control that activates but will not hold speed well, especially over bumps, down hills, or when you press decel. It sometimes will not engage unless you are "helping it" by already accelerating while holding accel. However the cruise works perfectly for me in a lower 4th gear (mistakenly diagnosed by me as lower speeds). It also works more reliably above 80mph.
I am still trying to solve this problem as many people have had it and said the solution is to reprogram the DME but I haven't gotten more detail than that. I hope this revised info helps someone else in the future, I suspect this problem is true for anyone who has swapped diffs to a lower gear ratio. END EDIT*
Hello all! First post here, of perhaps very many considering this car. Did some searching and couldn't find anything specific to my symptoms. Been driving this car for several years now without any major drama, mostly just maintenance. The car recently sat for about 7 months after a dif failure. Since I've been sitting on my ass during the pandemic I was finally able to find a good low mileage unit and have a shop I trust install it without breaking my limited bank. Since getting the car back it has a somewhat intermittent cruise problem, I'll switch to list mode to try and make it easier to understand.
-Cruise control turns on and light will stay on no problem even when CC isn't engaging. Sometimes it will engage with no problem and cut out later, other times it will just barely start to engage before cutting out. It SEEMS to happen more often when the car needs to keep from accelerating to maintain desired speed.
-2000 540i 6 speed with nearly 250k miles. Cruise has always worked smoothly until now.
-Originally thought it was voltage related, found out I had a SECOND bad alternator soon after dif replacement. (it has been a rough 2 months). Now alternator is fixed and cruise is still not working.
-Car is throttle by wire with all buttons for CC on steering wheel, to me this eliminates many possible failure points.
-Only other warning light is SES for air injection system (I suspect clogged ports) and codes that havent cleared from storage yet for an unhooked coolant sensor after the alternator was put in. This also seems to eliminate many failure points (abs) to me
-Visually, functionally checked brake and clutch switches, both seem to be working, brake lights work fine.
-I just got a creator 310+ but it seems many things give me a communication error, I can check and clear codes, see live data and ecu info, and even clear throttle whatchacallit. but it wont let me look at any of the sub systems. user error?
Any help would be much appreciated. I hope this long ass post makes sense!