Trans. allways shifting???

[kaycee]

I just got my 01 Silverado wtih the 5.3L and auto, it seems to shift 10 times more than the 5.7 Tahoe.I run about a 50 mile stretch of interstate with rolling hills and about every hill the 5.3 will kick down it is doing what it is supose to do but kinda annoying.The 5.7 will kick down about 2 times in this 50 mile stretch and the 5.3 will kick down about 6-8 times.My question is there any thing I can do to keep it from shifting so much? it doesn't seem to matter on MPH either 75 or if I go 80.These are the same trans. in them correct?

[Prop_Washer2]

Well the old 350 probably had a little more torque and maybe at a little lower rpm. Also the two may have different gear rations, i.e. 3.73's, 3.55's etc...could be different between the two. I had a 1996 Dodge Ram 4x4 extended, and it had a little 318 (5.2 Litre) and 3.55 gears, it would come out of TC lock up, on any slight incline at 60 mph...pain in the butt.
You might be able to check your Gear Ration by using the VIN number, one digit there represents the axle ratio...someone else on the board here may know...

[gmcman7202]

i feel the same way about my 02' sierra i been driving around in tow haul mode since it only changes the shift points, and the tc lock up. i am most likely gona get a pcm retune, hopefully correcting this. check over on the fullsizechevy.com board. i am sure they will know what needs to be done.

[kaycee]

Same rear gears,what is a pcm tune do you just put it in and go or is there more to it than that?Allso over there on FSC as 69_Bowtie

[gmcman7202]

well they adjust all the settings on the computer to suit your needs, as with gm, its one size should fit all, but it doesnt.

[1BadSS]

Originally Posted by gmcman7202

i feel the same way about my 02' sierra i been driving around in tow haul mode since it only changes the shift points, and the tc lock up. i am most likely gona get a pcm retune, hopefully correcting this. check over on the fullsizechevy.com board. i am sure they will know what needs to be done.

Tow Haul Also disables overdrive.

Turn tow-haul on if you dont mind lower gas mileage and it wont downshift on the hils.

[gmcman7202]

Originally Posted by 1BadSS

Tow Haul Also disables overdrive.

Turn tow-haul on if you dont mind lower gas mileage and it wont downshift on the hils.

no it does not. as at 80 mph, i am still runnning the same rpms at crusing, as i do without the tow haul on, it just moves the shift points around, and i actually get better gas milage with it pushed on, i have seen up to two more mpg's per tank with it on.

[1BadSS]

Originally Posted by gmcman7202

no it does not. as at 80 mph, i am still runnning the same rpms at crusing, as i do without the tow haul on, it just moves the shift points around, and i actually get better gas milage with it pushed on, i have seen up to two more mpg's per tank with it on.

The heck if it doesnt. Driving down the road in my 07, when tow haul mode is enabled the transmission drops 4th gear and goes into 3rd and stays in it until you slow down.

Thats the point of a 4speed overdrive and towing. It kicks it out of overdrive so you cant burn the gear up.

[gmcman7202]

well i guess fro your 07 it doesnt but for my 02 it doenst disable overdrive

[67ChevyRedneck]

What's the rear gear ratio? Anything below a 3.73 will cause the tranny to "search" a little bit. Are you using cruise control? Also, I think the tahoes tranny has a .7:1 OD ratio and the 99+ trucks have a .67:1 OD ratio.

A couple suggestions....

Slow down. These trucks weigh almost 6 thousand pounds, that's a lot of weight to move up a hill going 80 mph.

Try using cruise control (if you're not already doing so) I routinely drive drive to Columbia and Athens (each trip is about 2 hours) and with cruise set at about 73mph the truck will downshift maybe twice the whole trip.


6-8 times in 50 miles isn't bad either.... my girlfriends 05 tacoma has a 5 speed auto... you think your truck searches for gears... this thing will downshift on almost every hill, then sometimes kick back down to third then back to 5th

[67ChevyRedneck]

Originally Posted by gmcman7202

well i guess fro your 07 it doesnt but for my 02 it doenst disable overdrive

Tow/haul does not disable OD on my 00 Z71 either, it won't let it shift into OD until 60mph, and yes, the TC will lock.

[kaycee]

OK i have got 373 ratio,it does not search for gears it does shift like it is suppose to.I just hate when it downshifts on every little hill I would think that it would be able to hold this gear for some of the smaller hill.I just got the truck (month ago)and will try the tow/haul button.I thought there would be some kind of adjustment to help with out buying some $200 tune chip.Thanks for the reply's

[gmcman7202]

Originally Posted by 1BadSS

The heck if it doesnt. Driving down the road in my 07, when tow haul mode is enabled the transmission drops 4th gear and goes into 3rd and stays in it until you slow down.

Thats the point of a 4speed overdrive and towing. It kicks it out of overdrive so you cant burn the gear up.

another thing about the tow haul, i have burned a tranny up, towing thinking the tow haul is what i needed to do, without puttin it in 3rd, well i was wrong, all the clutches got fried. now i use 3rd when i tow with tow haul on.

[Huck]

Believe there is someting called a cam shaft timing sensor that goes bad over time and creates unnecessary shifts especially under light load. My is doing that almost like a major mis or too much shifting. Not sure where the cam sensor is but --will look into it.

[67ChevyRedneck]

Didn't think of this earlier, BUT if your Throttle Valve spring is getting old/weak it will cause the tranmission pressures to change enough to where the shift points are different. Many people solve this problem by purchasing a "trans-go" kit, which replaces the spring with a newer/stiffer one and a couple other things. Have not done this myself, but have read a lot on it, many people have done it. Go to GM-Trucks.com and do a search on "trans-go."

I also drove to columbia last weekend, and with this post in mind I paid attention to my truck. I set the cruise at 74 (speed limit is 70) and my converter only unlocked twice the entire trip (not counting the times I dropped the hammer to pass slow pokes.)

[Huck]

Reading the owners manual, it implies that Tow Haul doesn't disable overdrive but changes the shift points or rpm range between shifts. This increases line pressure to reduce unnecessary heat build up and reduces the number of up/down shifts. If you haul in OD, you will be lugging pretty bad and the trans will be downshifting way too often.
My problem is it searches for a happy gear around 50-60 under light throttle in OD. Drives me nuts. Speculation is ---fuel pump/pressure issue, torque converter clutch chatter?, trans line pressure, need computer error code check, etc. Where the hell is a good GM transmission who has the experience to say what is happening and why without me having to give some freakin dealer $200. for a computer hookup which will not tell me what and why but probably which credit card to use. Last time I did the computer hookup thing, it cost me $75. took 10 minutes and had NO ERROR CODES!!!!

[gmcman7202]

i have the same problem as you huck, with the happy gear situation. the whole seeking drives me nuts

[kaycee]

I went over there and looked and it seems Huck and gmcman need this mod,I think I got mine narrowed down to needing a custom tune but dam $$.Thanks for the input guys

[gmcman7202]

if you go with the wait 4 me its only 157 with a new pcm, but i am waiting to get cash for a diablosport with some custom ones made so i can switch it around. that will cost me about 400 or so.

[kaycee]

Do you have the wait for me tune?I have seen this one mentioned I want a plug in and go I don't want a hand held tuner.I'm still trying to figure out my VCR

[gmcman7202]

i do not have the wait for me, but i have spent many hours on fourms looking at my options, and with the cost and what you get, the wait for me seems like the best option, but the name implys the main problem that i have seen with the wait for me. i am only going with the diablosport, because it is a hand held, that also will tell you the trouble codes, has logging capibilities, so you can take that info, then send it to a tuner, who will tune based upon actuall info, thus you end up with a more specific tune, not just a plug n play. it also is alot easier to switch between economy, towing or balls to the walls tunes. its like getting a pcm tune where they run your truck on the dyno, but without all the extra costs

[kaycee]

Yeah I have read that some people are kinda mad at him for not replying to them .I have been looking and researching alot on the custom tunes allso and am at the same place I started I need to wait a month or 2 any ways for the cash

[gmcman7202]

my main problem is if i got a custom tune, i dont know what exactly i would want to get done to it. as i have trans mods down the line that i want to do, but the cash is funding other things right now, and thoes mods would need to be in the tune also, to maximize everything. this is another reason i am leaning toards the diablosport. another think i am not too sure on is the pcm stores milage along with the cluster. i think, and if you do a swap out tune, you might end up down the line with milage problems since the two dont match.

[kaycee]

Yep it gets confusing I don't think there is an issue with the milage problem someone would have said something about it.I see where some of them will upgrade your system for free if you add more mods.I am going to put a cat back exhaust on next month so that is why I am waiting allso.