Cruise Contol ???

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Thmsshaun

MB Enthusiast
Joined
Sep 23, 2004
Messages
2,630
Location
Ontario, Canada
Car
2009 C300 4Matic, 2012 Kia Sportage, 2015 Triumph Tiger800 XCX
Cruise Control ???

Went over to Nottingham last night (A50, M1) Using cruise control it would not cruise over 80. If I setcruise at 80 it would be be ok for a few seconds and then just cut off and start slowing.

Holding the cruise control lever up it would accelerate past 80 and the cut off again. If I then pushed the lever back up it would not accelerate. :confused:

Any ideas??

Thanks

*EDIT*

The fastest it would cruise at was about 76
 
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You have your 18's on dont you? IIRC Mick had the same problem on his C36 after he put his 18s on.

I have tried to recreate it on mine (which has 18's) and I cannot, works fine for me. The only difference being that I have lowered suspenssion but I cannot see that having an effect. :confused:
 
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It could be a problem with tyre sizes/pressures. Have you changed them recently?

If the wheel speed sensors detect that they are rotating at different speeds then the microbrain decides it's got a problem and turns off the CC. Any slight speed differential between wheels caused by size would be greater the faster you go. 80 may be the trigger point that causes the thinking beast under the bonnet to cry "Enough!"
 
Stratman said:
It could be a problem with tyre sizes/pressures. Have you changed them recently?

If the wheel speed sensors detect that they are rotating at different speeds then the microbrain decides it's got a problem and turns off the CC. Any slight speed differential between wheels caused by size would be greater the faster you go. 80 may be the trigger point that causes the thinking beast under the bonnet to cry "Enough!"
Makes the following thread look pretty stupid:

http://mbclub.co.uk/forums/showthread.php?t=12329
 
I can imagine the lines of code in the ECU:-

IF (big difference in wheel speed) AND
IF(rain sensor=TRUE)
THEN GOSUB floor throttle
ELSE ................. any suggestions?
 
Will have a check of my tyre pressures.

I am sure that it was OK when I first but the 18"s on although cant really remeber if I have driven with cruise at above 80 :rolleyes:

Hmm. IF the was the case wouldnt the speed limiter have a similar problem?? I set this to 80. Accelerated up to 80 and it held it without any problems.
 
Thmsshaun said:
Hmm. IF the was the case wouldnt the speed limiter have a similar problem?? I set this to 80. Accelerated up to 80 and it held it without any problems.
No, the limiter will work fine, remember all it does is prevent you from going faster, the cruise control will accelerate for you!

When the brake switch died on my previous car I had to make do with the speed limiter for a couple of months before the switch was replaced. It's not a patch on cruise control though :(
 
See what happens after I have checked tyre pressures. I take it if one side was softer than the other for example then this could have an effect.
 
Shude said:
No, the limiter will work fine, remember all it does is prevent you from going faster, the cruise control will accelerate for you!

When the brake switch died on my previous car I had to make do with the speed limiter for a couple of months before the switch was replaced. It's not a patch on cruise control though :(

Its good to have on that massive section of the M6 near stoke that has a 40mph limit at the moment :D
 
Mambo said:
Its good to have on that massive section of the M6 near stoke that has a 40mph limit at the moment :D
I always use the speed limiter on motorway 50/40 limit sections. I usually dial it up to 1 or 2 mph more (indicated) than the posted limit to avoid going only fractionally faster or slower than the other cars.
 
Shude said:
I always use the speed limiter on motorway 50/40 limit sections. I usually dial it up to 1 or 2 mph more (indicated) than the posted limit to avoid going only fractionally faster or slower than the other cars.

Wierd, mine only goes up in 5mph increments
 
Mine allows either 5mph or 1mph - try moving the lever in the other plane
 
I'm afraid it's an auto-pilot thing with me, but IIRC you pull the lever towards you to go up in 1mph increments :)
 
Shude said:
No it does not! Try moving the lever forwards and backwards :rolleyes:

You learn something new every day!

Will try that on my way up to manc land tomorrow!
 
Mambo said:
You learn something new every day!

Will try that on my way up to manc land tomorrow!


Will give that a try thought it only went up in 5's

Shude even though your rep has gone you are still a glorious beacon of light :)
 
Thmsshaun said:
Shude even though your rep has gone you are still a glorious beacon of light :)
I was a glorious beacon of light before this forum existed and you know it! :)
 
Thats the only thing i miss on my BMW , the speed limiter :(
 

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