MERVZ Tech Question

[RyanbabZ71]

MERVZ since you have connections at gm (at least i hope you might) could you try and find out something for me.

Can you find out any programming necessary for tire changes.  I went from stock P265's to LT285's.  I have the HPIII set and am wondering if its even working.  

Is there any gm people you could ask on this subject?  If so ask them what programs are available to me and other alike.

Thank you very much for your time and help

[Shaners]

Ryan,

Check against the mile markers on the Interstate next time your on it.  Those markers are pretty close especially if you go about 10 miles or so..........

[RyanbabZ71]

The speedo is working fine Its right on.  I am worried about other things like abs and now at around 35 seems the truck bogs down (runs rough) till i hit 40.  I dont know if its the trans or what.  

 

[Shaners]

Were you able to adjust the shift points with the HPIII?  It sounds like the converter is locking up in third too early...

[Shaners]

One more thought...  is it the same when you have the tow/haul button pressed??? I know you don't want to drive around with it pressed all the time, but if it doesn't bogg at 35 mph then it would be in your tranny somewhere...  My guess is big tires/early lock-up of converter/low RPM's are causing the bogg.

[RyanbabZ71]

i have been talking with the shop foreman he took my truck out with me for about a half an hr.  He said this was a common problem and they had a program to fix it but as of late gm took it out of their database as a fix.  Seemed it lowere mpg and people/gov didnt like that.  He is still talking to gm and is working on a fix.  

Funny thing i have had these tires for 7K and the problem just arose about 2K miles ago

Also seems to get worse and more noticable with a load in the bed.  Havent tried tow/haul.  What about driving around in 3rd?  What would be the negative effects?

Thanks

[Zane]

Sorry,

I've been computerless for the last day or so. Still messing around on a laptop while we get the new comp built.  Sounds like you got some answers, but i'll probe for ya.

[Shaners]

I don't think driving around it third will hurt anything, and when you get above 45 then put in "D".  

I know exactly what programming your tech is talking about...  my '00 Silverado had the same bog now that I think about it, and I had them (service) reprogram the the tranny.  He did say it would hurt fuel milage but I never noticed anything like that.  It moved my shift points  up a little higher and slightly increased the line pressure for minimal harder shifts.

My'00 excab 4x4 when empty and when I pulled out onto a State 2-lane, would shift into 4th at 45 and would lock-up between 50-55 when I started to back off the gas.

I'd check another dealer and see if he could reprogram for you...  there used to be a TSB about this problem but I don't remember the # of it...

[RyanbabZ71]

Shaners yea there was a upgrade for this problem but gm pulled it because it was hurting their epa milage.  He said gm is coming out with a new program.  

Im just scared im gonna hurt the trans or something