Down shifting on hills

[mmtr8man]

I have a 2003, Z71, 5.3, auto, 3.73 gears, stock size tires. it has 60K. It drives fine, but on the hwy. it wants to shift down on even small hills. It even does it on the interstate running 75mph on larger hills. It didn't do this in the past. Has anyone had this problem? the hills I'm talking about are on roads I travel offten, so its something that has gotten worse, Any ideas???

[95Sierra2500]

I'd say start w/the basics (fuel/air filters, check plugs/wires, check all fluids for burnt condition/metal shavings, etc.) and go from there. You're definately right though in stating that SOMETHING is amiss.

[hoorders]

I have a 2003, Z71, 5.3, auto, 3.73 gears, stock size tires. it has 60K. It drives fine, but on the hwy. it wants to shift down on even small hills. It even does it on the interstate running 75mph on larger hills. It didn't do this in the past. Has anyone had this problem? the hills I'm talking about are on roads I travel offten, so its something that has gotten worse, Any ideas???

 

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My 2000 Z71, exact same drive train as yours, does the exact same thing..........its a big pain in the arss...........I find it depends on where I am holding the accelerator pedal.........on small grades I need to give her a bit more gas so that it shifts into a better gear to get up the hill..........otherwise it just dogs its way up in overdrive.

[mmtr8man]

I'd say start w/the basics (fuel/air filters, check plugs/wires, check all fluids for burnt condition/metal shavings, etc.) and go from there. You're definately right though in stating that SOMETHING is amiss.

 

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the next thing is to replace the fuel filter, the engine runs smooth never misses, and gives about the same milage it has since new.

[srlbotanical]

I have a 2003, Z71, 5.3, auto, 3.73 gears, stock size tires. it has 60K. It drives fine, but on the hwy. it wants to shift down on even small hills. It even does it on the interstate running 75mph on larger hills. It didn't do this in the past. Has anyone had this problem? the hills I'm talking about are on roads I travel often, so its something that has gotten worse, Any ideas???

 

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It sounds like your transmission is changing line pressure and hunting for gears.

 

I am by-no-means an expert, but I have had to do tranny work on a number of Chevy's that I have owned in the past. Have you ever dropped the pan? Was your trans fluid changed at 30K? It's due again now...

 

60K is the perfect time to have a good tranny shop do a pressure test, and hook up a scanner for a drive test. Here in Michigan this is about 1/2 hour labor, so about $35 bucks. If you have any servos/valves that are starting to leak pressure, now is the time to find it. If you can catch tranny problems early, often a simple install like a transgo kit can prevent premature problems down the road.

 

Hope that helps,

 

Steve

[Clavin78]

I think its the gearing.

[Jim2002Z71]

I have a 2003, Z71, 5.3, auto, 3.73 gears, stock size tires. it has 60K. It drives fine, but on the hwy. it wants to shift down on even small hills. It even does it on the interstate running 75mph on larger hills. It didn't do this in the past. Has anyone had this problem? the hills I'm talking about are on roads I travel offten, so its something that has gotten worse, Any ideas???

 

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My 2000 Z71 5.3 3.73 did the exact same thing....then I bought a 2002 Z71 5.3 with 4.10's.. big difference...only drops gears on bigger hills now..