Cruise Control Speed Issues

[8675309]

First time poster but long-time reader of everyone's great insight!

First off, I LOVE, LOVE my new Genesis!

I have a 2009 V6 Genesis with Tech Package. On recent trips, I have noticed that the cruise control seems to slip quite a bit on uphills and downhills. So much so that setting the cruise control at 70mph will accelerate to 80 miles/hour on a downhill and conversely, uphills will slip down to almost 60 until it "wakes up" and increases the speed slowly back up to 70. My previous car, a V6 Toyota Camry would sense the very slight sign of an uphill/downhill and increase or decrease the speed to maintain the cruise control speed. This happens with only me and my wife in the car with no extra weight in the trunk.

My question...Are any other owners experiencing this or is this something I should have the dealer look at?

Thanks again for all your help!

Jeff

 

[Midnightsun]

Hmmm, have it looked at. Mine stays within about 1 mph. Heck it even applies the brakes on steep downhills. Then again the braking thing may be part of the adaptive cruise control on the 2010. Regardless, the variations are unacceptable.

 

[Disaster]

First time poster but long-time reader of everyone's great insight!

First off, I LOVE, LOVE my new Genesis!

I have a 2009 V6 Genesis with Tech Package. On recent trips, I have noticed that the cruise control seems to slip quite a bit on uphills and downhills. So much so that setting the cruise control at 70mph will accelerate to 80 miles/hour on a downhill and conversely, uphills will slip down to almost 60 until it "wakes up" and increases the speed slowly back up to 70. My previous car, a V6 Toyota Camry would sense the very slight sign of an uphill/downhill and increase or decrease the speed to maintain the cruise control speed. This happens with only me and my wife in the car with no extra weight in the trunk.

My question...Are any other owners experiencing this or is this something I should have the dealer look at?

Thanks again for all your help!

Jeff

That isn't normal. I use the cruise all the time to keep from getting tickets around some speed traps...at speeds as slow as 25mph. Since cruise control doesn't control the brakes, you can go over speed if the hill is steep enough (that it overcomes the engine braking) but it should control the speed within a mile or two up and down hills otherwise. Ours does.

 

[Pahaska]

With the high gearing in 6th, I commonly hit 70 or more with cruise set at 60 on the steep hills near my home. Speed picks up very quickly. Cars with lower gearing don't pick up speed so quickly on a downhill.

Unless you have a 2010, the cruise will not limit downhill speed.

 

[ShoNuff]

My v6Tech has the same issue - losing speed on inclines. Mine isn't as severe as the OP's, though - if I have it set at 75, it'll vary by +/- 4mph or so. Is this something that can be tweaked by the dealer fairly easily?

 

[ctrcbob]

Note that the V8's above (plus mine) do not have that problem, but the V6's do. Must have something to do with the lack of torque in the V6's at the low RPM's.

 

[ShoNuff]

Note that the V8's above (plus mine) do not have that problem, but the V6's do. Must have something to do with the lack of torque in the V6's at the low RPM's.

Bummer. I knew I should have had a V8!

The wife felt I'd be waaayyyy too dangerous with upwards of 400 ponies at my disposal. She was probably right, but still...

 

[Midnightsun]

Since cruise control doesn't control the brakes, you can go over speed if the hill is steep enough

Actually cruise control does control the brakes on the 2010 with intelligent cruise. No over speeding even on the steepest of inclines.

 

[Disaster]

Bummer. I knew I should have had a V8!

The wife felt I'd be waaayyyy too dangerous with upwards of 400 ponies at my disposal. She was probably right, but still...

Our V6 does not exhibit any issues with the cruise control. It is not a power issue. The V6 has plenty of power to stay within speed ranges. Heck, I've had econoboxes that didn't drift more than a couple miles per hour over normal ups and downs.

 

[Sayantsi]

I think it depends on how steep the hills are how much the car slows or speeds up, but the cruise control is definitely "lazy" - it is not stringent with staying on a specified speed but seems to have a wide margin. That is the ECU programming, probably for mpg efficiency. Its simply a matter of programming the logic to increase power as the mph drop from a target sooner.

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[Sayantsi]

Note that the V8's above (plus mine) do not have that problem, but the V6's do. Must have something to do with the lack of torque in the V6's at the low RPM's.

Due to the mechanical gearing of the two models, the low end acceleration and "grunt" is nearly identical at low speeds. The V8 shows its extra power most at highway speeds when accelerating. Fwiw, the V8 weighs altogether around 250 pounds more than the V6 - that means 20-25 hp are needed to keep it as fast as the V6, with the remaining ~55 hp being the true power advantage.

I don't know why a V8 would behave differently, I'd assume its in the ECU mapping. The V6 certainly has the power to maintain highway speeds - even at 70 mph, only about 20 hp is needed to keep a car traveling at constant velocity on a flat road, 50hp for a 6% incline. Both cars have much more power than that.

 

[Sayantsi]

My v6Tech has the same issue - losing speed on inclines. Mine isn't as severe as the OP's, though - if I have it set at 75, it'll vary by +/- 4mph or so. Is this something that can be tweaked by the dealer fairly easily?

This seems to be the norm ±4 mph. I'd love a reflash of the ECU hat kept it to 1-2 mph, but that means slightly lower mpg. I haven't heard of any factory reflashes for more stringent cruise control or quicker throttle response.

For the OP - it sounds like you have some pretty steep hills where you live, would you say so?

 

[CanukV6]

I had the same problem with the Cruise Control in my 2009 V6. It wouldn't hold speed uphill and gained speed on downhill sections. I recently had the car in for a service and the dealer made a number of "software upgrades". Now my Cruise holds speed almost perfectly even through some hefty inclines through northern Pennsylvania.

 

[Sayantsi]

I had the same problem with the Cruise Control in my 2009 V6. It wouldn't hold speed uphill and gained speed on downhill sections. I recently had the car in for a service and the dealer made a number of "software upgrades". Now my Cruise holds speed almost perfectly even through some hefty inclines through northern Pennsylvania.

This is good news - do you happen to know exactly what the dealer upgraded?

Maybe the OP can call the dealer and ask about the software upgrades that need to be made.

 

[michaeldallen]

Does anybody know when the cruise control hits the breaks for you, do the break lights come on to alert the guy behind us?

 

[Paulroger]

Someone verified in a previous thread that the brake lights do indeed come on when the car engages the brakes with the adaptive cruise control.

 

[Disaster]

Does anybody know when the cruise control hits the breaks for you, do the break lights come on to alert the guy behind us?

Since you aren't really slowing down...just holding speed...it shouldn't have to, but I expect it does.

 

[Midnightsun]

Since you aren't really slowing down...just holding speed...it shouldn't have to, but I expect it does.

If the guy in front of you breaks hard, the adaptive cruise does the same. I have played with it by cutting behind a slow moving car in another lane and believe me it brakes very hard if it needs to. I still have not found out if the brake lights work though under auto braking and would also like to know.

 

[nearwater]

God, I want the ACC.
Not that I need it nor do I get to use it often, but.. it's cool!

Dan

 

[CanukV6]

This is good news - do you happen to know exactly what the dealer upgraded?

Maybe the OP can call the dealer and ask about the software upgrades that need to be made.

My Service receipt doesn't specify what 'Upgrades' were installed, sorry.