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Pulsing Cruise Control

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Old Oct 29, 2004 | 09:22 PM
  #1  
Emsdad's Avatar
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From: Puyallup, WA
Pulsing Cruise Control

Hey has anyone experienced their cruise control pulsing? Lately I've noticed that when I set my cruise, it has a slight pulse in power, not a lot, maybe once a second and not enough to go up any MPH, but enough for me to notice.

Anyone seen this before? Any suggestions on how to get rid of it?


thanks in advance
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Old Oct 29, 2004 | 09:36 PM
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I haven't noticed it. Have you been using it on ground that isn't completely flat (small rises and drops in the road)?
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Old Oct 29, 2004 | 09:48 PM
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It maybe due...

...to the speed at which you initiated the cruise control. Sometimes, the cruise control can be caught "inbetween" speeds, ie. 55.5 mph. You can notice this because the speedo will move between 55 and 56 mph when cruising on smooth highway. In this case, the cruise control will seem to pulse on and off, in attempt to keep between the two speeds.

Simply try pressing Accel or Coast once and the cruise control should set itself to the next speed setting. Or, just make sure to initiate the cruise at steady state throttle. Hope this helps!

Arvin
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Old Oct 29, 2004 | 10:00 PM
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Speaking about the dig speedo. I noticed when I passed one of those road side radar meters with the big sign that the 8's speedo is off by about 3 MPH. So if the 8 speedo says 45 mph the radar sign says 42. Anyone ever notice that?
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Old Oct 29, 2004 | 11:18 PM
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Yes the speedo is off 3 mph, its been known on this site for a long time. I'm glad its off in that direction, saves some tickets. I love how you can advance or decrease your speed by one mph every time you touch thr cruz.
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Old Oct 29, 2004 | 11:20 PM
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Yes mine pulses.
And I can stare at the tac, but it never moves!

I know I feel it but the RP never moves or the sppedo.

Very strange indeed.

I think it's the rotory design. Most likely normal.
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Old Oct 30, 2004 | 12:42 AM
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I think mine does that too but I think its normal it was like that on my other car
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Old Oct 30, 2004 | 01:59 AM
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From: Rancho Cucamonga, CA
Mine does it but only if I'm going up or down a hill where it has to slow down or speed up to keep the speed.
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Old Oct 30, 2004 | 06:04 AM
  #9  
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I experience occasionally "surge" from the cruise control but only on downward or upward sloping gradients, hardly ever during normal level driving though.
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Old Oct 30, 2004 | 07:04 AM
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I've noticed that the cruise control will seem to surge if it is set when your foot is off the gas....ie: driving at 55 with foot depressed...momentarilty remove foot from gas...vehicle now coasting at 55....cruise control kicks in accelerator to maintain 55 and car seems to surge for a spit second. I use it as often as possible to avoid tickets especially the 1 mph increments.
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Old Oct 30, 2004 | 08:58 AM
  #11  
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I've noticed this a bit as well - but it's not the first car I've noticed it on ... I had an Acura Integra GSX in 1994 that did this. On both my 8 and on my Acura, it's dependent on the gear you're in and where in the powerband you've got things set.

The pulses in my 8 are most noticable when I'm locked on cruise above 4200 RPM - about 85 mph in 6th. That's the beginning of the "fat" part of the powerband and when the car makes slight speed corrections the power comes on strong there - I don't think they calibrated the unit just right for this level of power.

Not noticable below 4000.

Same issue was on my Integra - above about 4000 (which was similar speed on it as well - short gears, 8200 RPM redline), the cruise felt surgy-
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Old Oct 30, 2004 | 05:44 PM
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Well I never noticed it before, and then I left on a trip for a week, and when I came back, I've noticed it now on two seperate occasions. I really hope it goes away, I don't like taking my car in to the shop. But I can't stand the pulsing, it's very annoying.
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Old Oct 30, 2004 | 06:28 PM
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Yep...I have the pulses too. I was told by my dealership that it is because the whole system is digital and very tight. The computer is trying so hard to keep it at the set speed that it seems to pulse rather than maintain a smooth speed. Don't know if that makes sense the way I explained it.

Trying to hard to keep an exact speed...'pulses' are the result.
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Old Oct 30, 2004 | 11:53 PM
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This is the best cruz I ever had in a car. It's real accurate. The best MPG I ever got is when I set it for 65mph on a long trip and got 27.5mpg! It's hard to "Set it and forget it" because you want to have some fun reving it to the Red Line. This car like all my other rotarys is hard to discipline yourself to go for the gas milage. So I dont try for it very often I just cherish it. Enjoy!
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Old Nov 1, 2004 | 11:34 AM
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I have noticed the pulsing also. However, at 15,000 miles, I have either become used to it or it doesn't do it anymore. It used to drive me nuts.
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Old Nov 1, 2004 | 06:58 PM
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Mine has the pulsation as well. Hence I avoid using cc - way too annoying... especially on a slight incline. The way it feels, it's like the ECU cuts injection periodically. Someone with more experience - is it possible the low load conditions when cruising make the ECU cut power to one of the rotors, then alternate between the two of them? Similar to how some V8s cut power to 4 cylinders under low load.... This would be the way to really improve mpg Just not for me.
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Old Nov 1, 2004 | 07:18 PM
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I too no longer use the cruz control because the pusling was aggravating. My wife thinks I'm nuts (she may be right though). I haven;t tried it in a while. Maybe the last flash changed somehting
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Old Nov 1, 2004 | 07:28 PM
  #18  
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From: portland oregon
Originally Posted by bxb40
Someone with more experience - is it possible the low load conditions when cruising make the ECU cut power to one of the rotors, then alternate between the two of them? Similar to how some V8s cut power to 4 cylinders under low load.... This would be the way to really improve mpg Just not for me.
No it does not do this- nor does Mazda have any plans to do this in the future. its not the direction they are looking in....

do a search on "surging" or "surges" and cruise control and you should fina at least 2 other threads discussing it. some people have it some dont. i believe its more of a "prevailing conditions" kinda thing instead of differences between cars. like others have said the gear,speed, rpm etc that you set it at seem to have a bit to do with it. i have never experienced it my self and have used the cruise on several long distance trips and a couple of times around town and have not been able to replicate this.

edit- actually instead of doing the search just read the "similar" threads listed at the bottom of the page.
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