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Fluctuating Cruise Control Speed ???
- Thread starter pcb
- Start date
Justin2129
Member
- :
- 2002 Mazda Protege 5
ive never noticed that on mine
It's not that noticeable but it really shows up on my Ultragauge. My fuel trim, O2 readings, and especially my instantaneous MPG are always moving around.
I'm thinking the people behind me are thinking I don't know how to keep my foot steady on the gas. (it's only 2-3 mph every 10-15 seconds).
I'm thinking the people behind me are thinking I don't know how to keep my foot steady on the gas. (it's only 2-3 mph every 10-15 seconds).
Justin2129
Member
- :
- 2002 Mazda Protege 5
hmm ill check mine against my scangauge next time im out
tweety2300
Member
- :
- 2001 mazda protege mp3
My moms vibe will run over 5mph what its set for sometimes.
I'll set mine and it stays there for just a few seconds then slowly speeds up three miles an hour then the throttle backs off and it slows down three miles and hour then starts over. It's very cyclic and perfectly timed to cycle every ten or fifteen seconds. Up and down the whole time it's on cruise. It's not that bad but I'm gonna ditch my instantaneous MPG on my Ultragauge and replace it with an average instead. The roads around here are almost perfectly flat and straight so it's nothing to do with climbing hills.
sleepwalker
Member
- :
- 2010 Mazda CX-7 i Sport
My moms vibe will run over 5mph what its set for sometimes.
I'm generally anti-Your-Mom-jokes, but my mind grabbed this like a fat kid grabs a corndog.
[OnTopic]
Granted, I live in Missouri, where south of The River we mostly scoff when someone says they found a flat straight stretch of road, but on the interstates you can find them, and I can't say I've really noticed this happening. She's usually pretty good at staying within a mph of where I set it. I'll have to pay more attention next time I run down I44.
Justin2129
Member
- :
- 2002 Mazda Protege 5
i checked mine on the scangauge today. it fluctuated between 45 and 47 when i had CC on
i checked mine on the scangauge today. it fluctuated between 45 and 47 when i had CC on
I guess that's good news,... that means it's probably normal then and I don't have to fix anything. Did your scangauge show the numbers constantly moving too?? (like instantaneous MPG, fuel trim, O2 readings ect.)
Justin2129
Member
- :
- 2002 Mazda Protege 5
Did your scangauge show the numbers constantly moving too?? (like instantaneous MPG, fuel trim, O2 readings ect.)
yes
kamesama980
Member
- :
- 2002 Protege5
Yes, it's normal. My wifes car does it too. Nothing to do with hypermiling. Has to do with the mechanics and programming for the cruise system. The car doesn't know exactly how far to push the pedal, no tables to look upandno predictive algorythm. All it does is read the VSS speed and if you go too low, it opens the valve on the cruise control servo momentarily to open the throttle. Once you get to the upper limit, it opens the other valve to vent some vacuum from the servo and close the throttle slightly. All cruise control systems do it to some extent, usually not noticeably though. the P5 is the worst I've noticed and I've owned and driven a pretty wide variety of cars.
I actually noticed it by feel first then confirmed it when I got a SG2. According to the SG2, at any given speed I can usually average 1.5-2 mpg better than the cruise by having a steady foot and if there are hills, predictively adjusting my foot rather than responding after the speed changes (up or down).
I actually noticed it by feel first then confirmed it when I got a SG2. According to the SG2, at any given speed I can usually average 1.5-2 mpg better than the cruise by having a steady foot and if there are hills, predictively adjusting my foot rather than responding after the speed changes (up or down).
