JohnnyCake

I have an 06. I've confirmed that this does not happen on earlier models -- Mr.. Blister pointed out that the transmission changed with the 06 so maybe that's why.

Anyway, here's the test:

1. Engage speed control at a highway speed.
2. Deflate the lumbar support completely. Hold for a few seconds after fully deflated, then release
3. Next, press the lumbar control repeatedly, as if you wanted to deflate it further (even though it is fully deflated), relatively quickly (maybe half second or so intervals).

See whether the speed of the car "lurches" or speeds up for a fraction of a second.

I can have this repeat reliably. I am trying to figure out whether it is related to something else I am working on or whether it is present in all stock 06 vehicles (and presumably later).

Lots of good karma coming your way for trying this and reporting back!

huy33

What speed do you think we need to be going? 60+??

I meant for this part:

1. Engage speed control at a highway speed.

mrblister

Johnny . I noted that when I have my cruise engaqed and I am going up hill the engine does surge to maintain speed . I am sure yours does the same. I went to look at the 2006 brochure because I think that your cruise control sysytem also changed in 2006. I cant find it. Do you have the 2006 specs.

Buddy

JohnnyCake

huy33: I can feel this at almost any speed on cruise, but I think it is easiest to detect on the highway (45-65).

mrblister: I'm not talking about a gradual increase in RPM, like smoothly occurs when going up a hill. Rather I am talking about a brief surge -- not throw you back in the seat and hold you there, but a definite, but very brief, moment (fraction of a second) when the car jerks forward.

76210Guy

Mine does that when I have the cruise on and go up an incline. It is almost as if it drops into a "passing gear" sort of mode for a second. Figured it was normal. My Benz and BMW did it too as I recall.

eliotd

finally got to drive wife's car and had a chance to try it out and did NOT notice any surge at all with three or four different attempts to replicate...sorry!


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JohnnyCake

Thanks ellotd -- if anyone else has an 06 or later, please test.

Here the situation. I have the Beatsonic adapter installed to disable the Nav "lockout when moving," so I am able to enter destinations for the NAV while moving.

Overriding the speed sensor involves interrupting a single wire with a SPST switch. Anyone could do it with a $1.29 switch from RadioShack. The only advantage of the Beatsonic adaptor is that you do it without cutting any wires, but there is no electronics in the Beatsonic adaptor. Just interrupt the wire and the car thinks you are stopped (but only for about 30 seconds, oddly enough).

However, engaging or disengaging the override causes a brief "surge." Then I coincidentally noticed that surge was also present when using the seat lumbar control. Whether that was there before the wire was interrupted, I have no idea. I discovered that purely by chance.

I also noticed that sometimes the cruise control disengages and the "cruise" light begins to flash when the wire is interrupted. However, the cruise can be just be re-engaged and does not require a power off restart.

I really have no explanation for this -- seems like some sort of electrical thing obviously. Any guesses welcome.

Harold57

It kind of sounds like one of the engine related computers is monitoring that signal since you notice the surge and the cruise control disengages. I haven't figured out a tie in for the lumbar support though unless it is trying to be like the ECU that controls acceleration and is trying to be a nanny telling you to quit messing with the seat while you're driving.

tfischer

This is all mildly curious from a technical standpoint, but is this phenomenon causing any problem, hazard, danger, inconvenience or noticeable aberration from the normal performance of the car or any of its systems?
I can't recall the last time I deflated the lumbar support with the cruise control engaged at highway speeds, or at any other speed. In other words, I'm having a hard time getting any useful information out of this story.

JohnnyCake

Socrates: "The unexamined life is not worth living"

This is just so odd, that I was interested an an explanation. The lumbar was just an accidental discovery. The main point is that the surge happens when I override the NAV in-motion lockout.

Several forum members have sent me a PM asking which wire to interrupt with a $1.29 switch from Radio Shack to achieve the NAV lockout override. But I am a bit leery of being the source of this without knowing why the override effects the car's speed. Unintended acceleration is something to be cautious of, even if it only lasts a brief second.

tfischer

"The unexamined car is not worth driving."
PS: many great inventions and discoveries through the ages were accidental. I don't think this is one of them, but it is important to keep nosing around things all the time.
You never know.

mrblister

Johnny I think what you need is to call Sam at Beatsonic see if his tech people have a explanation for you. Maybe he can tell you of another owner that bought the nav overide that installed it on a 2006 like your car. I have not found that symptom on my 2005 .

BUDDY