V2 Throttle control problem

[RapidRob]

Originally Posted by bergstpg

I added this note to another thread - but want to continue here till resolution.

The latest is the snow tire size is slightly larger than the stock tires and they think this might be the issue. Stay tuned.

Which winters do you have installed - Sottozero Winter 240's ?

Rob

[Razorecko]

There is no way the tires are the cause of this. The Cts-v isnt an awd vehicle thats affected from different wheel sizes.

[Hogg]

The missfire could be an issue calibration as could the throttle issue. These cars are brand new, and as everything nowdays, is rushed into production.

As GM gets some in the field info coming back from its customers, the updates to the ECM calibrations can be made to fix the numerous drivability complaints that will inevitably ensue teh release of a new vehicle.

This is the sole reason I dont suggest buying of the 1st year of a new vehicle run.

You can enter your VIN into this GM website and check for new calibrations for your vehicle. I guarentee there is/will be a flood of new calibrations.
http://tis2web.service.gm.com/tis2web

Good luck with your car. These V's are awesome cars.
peace
Hog

[bergstpg]

Remove this thread?? Do you work for GM or something??

I am reporting as I get it. I didn't spend 72k on a Cadillac to roll over dead and expect this car when I am driving a car with the check engine light on and the car surging in idle. Back to those that may be interested.

The tires are Pirelli SOTTOZERO W240's. 255/40 R19's in the front and 285/40 R19's in the rear - so I believe they are a little taller than stock. Again, I didn't pick them out - Discount Tire's corporate did.

[Hogg]

Originally Posted by bergstpg

Remove this thread?? Do you work for GM or something??

I am reporting as I get it. I didn't spend 72k on a Cadillac to roll over dead and expect this car when I am driving a car with the check engine light on and the car surging in idle. Back to those that may be interested.

The tires are Pirelli SOTTOZERO W240's. 255/40 R19's in the front and 285/40 R19's in the rear - so I believe they are a little taller than stock. Again, I didn't pick them out - Discount Tire's corporate did.

What, no I simply screwed a post, and dont know how to delete it.
I want my screwed up POST deleted, not the THIS THREAD. Please re read.

No one is telling you to roll over an play dead. You should get an awesome car as it is a Caddy.

I am trying to help you by explaining the way GM issues recalibration for customer compliants.


BTW I am very interested in your problem.

And no I dont work for GM anymore.

Whats with your attitude? I'm just trying to help.

peace
Hog

[urbanski]

hogg, got it

OP, relax w/ hogg. thanks.

[bergstpg]

Sorry Hogg - my bad. I miss understood what was going on.

[bergstpg]

Service tech called back again. They working with Cadillac to change a setting in the computer to compensate for the 5 mm change in height of the snow tires. They are going this route because they don't have any tires to swap without swapping out my wheel's snows with the orginals - don't have an extra set of rims yet. He also said he was 95% sure this was the issue since everything else has check out.

Does anybody else have snow tires? I know they do. I believe there isn't a snow tire built to exactly the same size, so there should be others having this issue - if this is truely the right hypothesis.

[wait4me]

Ok your problem is because you changed the rear tire size and now it is tooo far off from the front to rear and that is why the system thinks you are loosing traction. Stability control is not kicking in, just traction control.

Stock tire size for the front is, 255 - 40 - 19 which is exactly 746.10 revolutions per mile and 84.92 inches in curcumference.
Stock tire size for the rear is, 285 - 35 - 19 which is exactly 751.02 revolutions per mile and 84.37 inches in curcumference.

That is releatively close in terms of pulses per mile so they have it probably set up to be very close and just allow a little bit of slop before it will start seeing the difference and will start thinking it is loosing traction. Obviously they have to set that "GAP" to never happen in 200 mph. Because the faster you go, the more the difference between the front and rear tire pulses will be.

Now, your new rear tire size is messing with you.

The tire size you now have being 285 - 40 - 19 is 720.9 revolutions per mile. Way off in terms of pulses per mile of the wheel abs sensors. They will be close till about 28mph and still within range, but then as you go past that point, it will start to be too far off from the safe zone and will then think you are loosing traction on the front 2 tires.



Changing the tire size in the computer will not fix your problem i dont think. It would be an abs adjustment, and by changing this to fix your error would result in LESS than ideal traction control when you change your tires back to the summer ones..

[The Tony Show]

^ ......and there's the answer.

[Kadonny]

Originally Posted by bergstpg

Does anybody else have snow tires? I know they do. I believe there isn't a snow tire built to exactly the same size, so there should be others having this issue - if this is truely the right hypothesis.

Tirerack has the right size in the Sottozero for the rears. 285-35-19.

[Razorecko]

short-throw has on winter tires and he has no issues. I'm still firm on the belief that it doesnt have anything to do with the tires.

[jwa999]

Been driving my new cts-v for a few weeks now. almost 2000 miles. One thing I notice is that when you downshift, it does rev matching, which causes the car to jump forward. I ammainly used to manual transmissions and will always break by downshifting. Not with this car, there is no point at lower speeds. It jumps a little bit. Perhaps this is what you are experiencing when you take your foot of the accelerator. If it's in automatic mode, i know it will sometimes downshift when you slow down. Perhaps it depends how your driving style programmed it. Personally, i don't drive in automatic mode much. It is just not very responsive. My wife's m45 automatic transmission is much better. I never struggle with it, and usually only use manual mode to downshift for breaking.

[bergstpg]

I guess it really sounds like this is it. If it is, I hope there isn't anybody planning to burn rubber off their rear tires otherwise you will start to lose throttle control the more you burn off. If +5mm is measurable at 28 MPH, which the speed seems to match my test, -5mm could be similar. I would imagine -2.5mm is more likely for tread loss - would that be seen at twice the speed (60 MPH). Probably not, but at some speed higher than 28 MPH you will likely see this on all cars if the rears wear more the the fronts. But more wear to the rear tire will never happen in the V2.

I have asked Discount Tire to swap out my oversized tire - still waiting for a response from them. At the same time, Cadillac is probably going to want to use my car as a test subject so they can put out a bulletin, however, if this is the fix - to adjust the computer - I don't want to do this twice a year. Still going to push for the right sized rears.

Stay tuned. Probably won't hear anything more until Monday at the earliest.

[bergstpg]

jwa999 - My car does the samething in manual mode, but, the problem happens in automatic and manual mode, and does it until I either step on the gas or the brake. In addition, it isn't in the process of shifting gears - since it is in idle when noticed. Another point to note is that sometimes the car will not let me turn off the TC. I push - hold - no hold - put car in park - etc and it won't turn it off. When this happens I have to turn the car off before I can disable it again. And yes, it has the uncontrollable throttle during this situation as well (same speed around 35).