Took my Tahoe in for drivability issue that I am having with the throttle lag ...anyways long story even longer took it in to the Dealer and the service writer tells me that he had his guy look at it but can't do anything until I put the factory wheels and tires back on. Itold him I was having the problem even with the 17 inch wheels but he still stood by his original statement. I even went so far as totell himthe VCI code for the 20 inch wheelsthat ZX supplied me but same story....I am going to have toreinstall my originalwheels and tires before they will even look at it. Does this sound normal???

 

doesnt sound normal to me...not sure what wheel size has to do with throttle lag.
did you upgrade to OEM 20" wheels, or aftermarket? I wouldnt think it would be an issue if OEM 20's are installed and the trucks software was updated accordingly.

 

I just got off the phone with the Dealer again ..actually the shop foreman, I was trying to explain to him that the tire diameter of the stock 17's and my new 20's were not that far apart...stock tire size 265 70 17 and my new tire size of 305 50 20 .



Stock Tire - 265/70R17
Overall Diameter:
31.60 in
802.64 mm

New Tire- 305/50R20
Overall Diameter:
32.00 in
812.8 mm

Diameter Difference: 1.25%

Anyway he said they cannot do anything until the factory wheels were installed because GM won't let them do any work on modified vehicles.
I asked him why they couldn't program in the new VCI code and then try and diagnose my problems..but yet once again he reverted back to GM policies.

Ironcy, I agree with your statement...the throttle lag problemhas nothing to do with the new wheels and tiresbecause I was having the lag even with the 17's installed.
Looks like I will putting the old wheels and tires back on..Thank the good Lord that I still have them.

 

Have you tried checking with a different dealer?

 

Not yet..he is the closest one to me but I may have to go that route. You would think that after 6 vehicle purchases from them within the past 4 yearsthat might mean something...evidently it doesn't.

 

too often the "sales" and "service" departments of dealerships do not operate on the same loyalty system...although your continued business on the sales side of the dealership "should" entitle you to expect the Service teamto go above and beyond to help you on this issue...my advice, take your business elsewhere...and make sure the general manager of the dealership knows. good luck with your problem.

 

Take a look at this thread. https://chevroletforum.com/m_25380/tm.htm

Ask the service dept to update the computer with the latest software. That might help.

 

^^good catch...I think a lot of people called that the "E85 update."
Might want to find out if your Tahoe has received this update...below is from the "Reprogram List Sticky Thread"

New software for E-85 calibration:

Hold off for now as there seems to be a throttle lag issue related to the new software...

Zx --The lag is caused by the updated engine control module calibration software that was written to ensure proper ethanol content calculation. Evidently it is leaning the mixture out during certain operational conditions, hold tight and GM will release an update to resolve this issue.

Original post...
Zx--The product enhancement listed above #06162 - (12/13/2006) is a new software set that simply adds a broader range of operation to the Virtual Flex Fuel Sensor (VFFS) so that the engine will start and run smoother when various amounts of Ethanol is detected in the tank.
It has no effect on drivability when running gasoline containing less than 10% Ethanol.

 

This sounds exactly like what is happening with my vehicle, I wonder if mine got the E-85 update before I took delivery of it.

Anyone know if GM has released an update to fix this yet?

Thanks all !

 

Let me start from the top since I have been away from a computer for the past 4 days.

The VCI I supplied was for 275/55R20 not 305/50's so please don't use it, I should have clarified the tire size.

GM does not provide VCI codes for none OEM tire/wheel sizes.


Evidently (from your PM) it is clear that your dealer does not know the procedure to install pre-loaded updates, this is common with many dealerships and the reason I provided you with the numerical VCI number as well although it is incorrect.

The hesitation is not related, and is most pronounced during aggressive driving or when going from idle/coasting to abrupt heavy throttle applications, this is normal.