Problems when Towing [long...]

[Matt_Lewis]

Hi All,
This is my first post and I must say I appreciate all the information I have received from viewing this forum.

I bought a 2005 LS 4wd with the 3.42 gears with the main purpose of pulling my camper. My camper only weighs 2800lbs and is only 19ft long and with the 5100lb towing capacity on the TB I figured it would have no problems. And for the most part I was right, for the most part.

Since I bought the TB I have been on two trips; one that was for strictly braking-in purposes and one for vacation. The first trip I had no problems whatsoever and while pulling the camper I could barely tell there was a camper behind me, it towed like a dream. But that being said, I didn't travel on the interstate and I kept it under 50 mph as stated in the manual and living here in the south there aren't many hills except for the over-passes. The second trip is where I had problems. According to the manual for the first 500 miles towing you are only supposed to go 50mph so I broke the trip into two days driving to allow the TB to rest. The first day was fine, no problems the TB towed like a dream. The second started out good, we were starting to get into some hills but still everything was good. After about 4 hours of driving I decided that we should get lunch and stop for gas. After the stop which was only about 30 minutes we got back on the road. Once, I got back on the road I immediately noticed that something was different. I had been towing in 3rd and at 60 mph the TB would be running rpms at about 2200. Now for some reason it was running at 2600-2700 and wouldn't shift down. This didn't concern me too much because of all the hills I figured it was working harder. But then we came to a red light after the complete stop, taking off was a problem. The shift from 1st to 2nd was very hard, and the same for 2nd to 3rd. I first thought it was the transmission but then once I got into 3rd it had no problems, it was just getting there. Luckily, we didn't have to make many more complete stops but for every one after that it continued to shift very hard. After unhooking which was only a couple of minutes I turned off the TB and started it right back up and when I drove it, everything was normally. This got me thinking that it wasn't anything to do with the transmission and more the computer and it's shifting points.

The whole time while on vacation without the camper behind us, we had no problems with shifting. Going home, I again broke it into two days and the first day driving straight to the campground, no problems. The second day before we stopped to get gas, no problems after stopping for gas and getting back on the interstate, the same exact shifting problem occured. Once, I got home unhooked, stopped and started the TB and drove it...no problems shifting.

I apologize for such a long post. Does anyone have any ideas? Does anyone else tow? Do you have any problems?
Thanks in advance.

[dpm6836]

Sorry no help from me only advice. I would direct your question to someone at GM. There must be a customer service number and someone eager to get you correct info. Don't rely on a local "transmission Specialist" or a dealership.
I would be concerned about possible damage if this keep occurring. Transmission aren't cheap and remanufactured/rebuilt seem to only last so long (my past experiences with Ford tranny).

[sallen]

I tow frequently with my tb, and i talked to the dealer about towing with the tb, and they highly recomended that i didnt tow for the first 5,000 miles, for the trany to break in, honestly i wouldnt have towed that soon, but i would definatly take it in and talk to someone and describe the problem,

shay

[dstraka22]

We just returned from a 1300 mile trip around lake michigan. We are towing a 3800 LB trailer and i have intalled a B & M trans cooler. I did notice a few harsh shifts around 5 hours into driving one of the days. I proceeded to turn off the air conditioning and then i didnt notice it the next stops that we had. it could have been due to the head wind that we encountered at that time or a computer glitch. i am not sure. our last day was a 6.5 hour drive home and i had no problem then. i plan on installing a trans temp gauge to monitor the temps but i am sure they are fine. we only have about 2600 miles on our 2005 EXT so i will monitor it and see if there is any change.

I was thinking about changing the thermostat to a lower temp to keep everything a bit cooler. I cant understand why in the world chevy didnt install electric fans for cooling insted of robbing horsepower with the fan and clutch.

[Matt_Lewis]

I appreciate the info. I guess I should have waited a little longer before towing but I did everything by the manual so hopefully I didn't mess anything up.

I first called the dealership and told them my problem and their first thought was the fan clutch but then when I got there they told me that it was my brake controller. They said that because my brake controller was an inertia-activated it has to be leveled properly and because I didn't install the controller myself I couldn't tell them whether or not it was leveled properly.

I have since leveled the controller and I hope this is the fix, but somehow I don't think this has anything to do with it. I have searched online and found a few TSBs that have the same description except they get the Check Engine Soon light and I don't get that. It mentions something about the torque converter locking up.

Again, I appreciate the help!

[Matt_Lewis]

I called Chevrolet today and they really couldn't help me without a diagnostic run to make sure there wasn't some sort of trouble code stored. They said that there wasn't anything as for as TSBs or Recalls that they could find. So I called the dealership to schedule an appointment I also asked them about installing an aux. transmission cooler and they said that they can't install any aftermarket parts on the TB. I asked them about just a transmission gauge and they said, "No" to that too. Is this right?

So I think I will install the temp gauge myself to see what is temp it is actually running at. Does anyone have any suggestions on what type of gauge (mechanical or electric) and where to mount it? I read that you can install a transmission temp gauge in the "test port." I apologize for my ignorance but, what is a test port? Where is it located? Is the test port an accurate reading?
Thanks
Matt

[ScarabEpic22]

Sorry, I have no idea why your TB does this. My 02 has around 52,300miles on it, and tows like a dream all the time. A/C seems to make the engine sound as if it is working harder, but the RPMs dont increase, and mileage doesnt decrease. But, my TB has the 3.73 gears, not 3.42. I am debating a aftermarket tranny cooler and guage to make sure it doesnt get to hot on long trips. I tow my 3900lbs boat through Eastern WA during the summer, where the temps are occasionally around 95-105F. Anyone know about how much I should expect to spend if I install it myself?

P.S. Has anyone installed the suspension air bags that go inside of your rear coils? If so, has it helped at all?

[Matt_Lewis]

Well I just got my TB back from the dealership and while they couldn't get the harsh shifts they did update by pcm with the latest codes that were to address harsh shifts complains by other TB owners. (or at least that is what they told me!) They also mentioned that my transmission fluid level was a little higher than normal, so they took some out. How? I'm not quite sure, can you empty just a little? Would having too much transmission fluid cause problems?
Thanks
Matt

[mbopp]

Well, I use the Envoy to tow my 2500# pop-up. Back in July 3 things happened at the same time: The SES light came on, the cruise control died, and it started shifting really hard. So for about the 4th time now the dealer re-flashed the PCM.

[autotech]

I am not a transmission specialist, but I do know a few things about these transmissions. First off, they are adaptive. What that means is that they monitor the amount of time it takes to physically shift to the next gear. If it takes too long, it will adjust the line pressure to compensate and lower the shift time. That may account for some change in shift feel at times. But what you are describing does not sound like that is the cause. The transmission has an internal fluid temp sensor and if the trans is getting too hot, it will boost line pressure to quicken the shift to reduce slippage (slippage = heat), that is the bang from gear to gear. And sometimes it will lock the converter sooner to reduce slippage there. That may make it feel sluggish on acceleration. The torque converter is the major source of heat in a transmission. A lot of times once the vehicle goes into the "hot" mode for the transmission, it will stay that way until the key is cycled. I hope this helps.

[autotech]

I forgot something. If you are haulling a heavy load up hill or maybe pulling a boat up a ramp out of the water, you can build up a tremendous amount of heat in a very short time. When the torque converter is loaded up, i.e. when the vehicle is stopped and the engine is revving up, there is a lot of fluid friction inside the torque converter and it heats up very fast. You should let the vehicle idle in park for 10-15 minutes after pulling a load to bring the trans temp back down. This should help extend the life of your transmission. But best thing you can do is have it serviced or flushed on a regular basis. That is just my personal opinion, but I see it first hand every day a work, so take it with a grain of salt if you want.

[04TBEXT]

:m2: Towing with a sizeable load (i.e larger boat, enclosed trailer, etc. plus passenger and luggage) in overdrive with a numerically low axle ratio can really create a challenge for the transmission cooling system. Some SUV's with these low numerical gear ratios, towing @ legal highway speeds will "lumber along" with engine RPMs just above idle speed. Low engine RPMS = low transmission pump speeds. Low transmission pump speeds can increase transmission fluid temperatures. The faster the oil can be circulated, the more efficiently it will be cooled. The "disable/safe" mode as described by Autotech happens for just this reason.
Sometime towing in "D" instead of "OD" can help which results in higher engine RPMS/transmission pump speeds. It really sucks with today's fuel prices, but could save in transmission wear and repair costs over the long run.

[ScarabEpic22]

Yea, to add on with what 04TBEXT and autotech said... You should never, never tow anything in D. Always tow in 3, and your truck will run cooler and last longer. This is my view on the situation.

[jimmyjam]

Yea, to add on with what 04TBEXT and autotech said... You should never, never tow anything in D. Always tow in 3, and your truck will run cooler and last longer. This is my view on the situation.I can second that, I blew out the transmission in my sister's 95 4x4 blazer towing a trailer 800 miles in OD. Ehh, she had just finished pharmacy school so she could afford a new car... Next time she can pay for a moving company.

[Matt_Lewis]

Again, I appreciate all the responses.

The couple times I have pulled the camper it is only in 3rd gear. However, the dealership told me, and the manual confirms this, that it is ok to tow in "D." But I agree with autotech and 04TBEXT, and I will continue to tow in 3rd.

I think that autotech may be on to something. I didn't notice the harsh shifts until after I stopped to get gas, thus leaving the TB not running which according to autotech may have caused heat build up because nothing is moving to cool everything down. I was thinking about installing an electric fan to help cool everything while sitting at the gas station and to help keep things cool while moving without the lost of horsepower. What do you guys think? Also, would letting the TB idle while getting gas help cool everything down?
Thanks again,
Matt

[jgray_22]

When I first bought my 05 Envoy, I was told of the 5100lb towing capacity. The Envoy has a 5750lb gvwr. Curb Weight of 4594lb. Payload of 1156lb. Doesn't that mean I can only tow 1156lb. What is the correct number to follow. I towed one time so far. 2 4wheelers with 6x8 trailer. I would guess around 1100lbs. I wasn't very impressed with it. I don't know how you guys tow these 2500lb popups and stuff.

[ScarabEpic22]

Nope, your TB can tow right around 5100lbs no problem. Personally, I am going to add an aftermarket tranny cooler and the airlift 1000 air bags to help compensate for the extra weight. I tow my boat across Eastern WA in the summer, and my TB tows it fine, engine temp is the same it always is. Also, I found the TB got a little better towing as I towed more, kinda weird, but it did.

[Matt_Lewis]

jgray_22,
Depending on the specs of your Envoy, it should be able to tow around the 5000lbs like you were told. This is how the tow rating is normally calculated (I am going to use the specs on my TB, but it should be really similar to yours):

2005 Trailblazer
3.42 axle ratio
LS 4wd
GCWR(Gross Combined Weight Rating) = 10,000lbs
Curb Weight = 4594lbs

So, theoritically the GCWR-Curb Weight will give you a rough estimate of your tow rating. BUT you then would need to add your weight, your passengers' weight, weight of gas, misc stuff in the truck, etc. So let's assume all that weighs 500lbs. The calculation would look something like this:
10,000 - 4594 - 500 = 4906lbs

This leaves me with a tow rating around 4900lbs. I hope this helps. It gets a little confusing once you start adding weight distribution systems and towing bigger trailers, but this is the basic calculation.
Matt

[jgray_22]

thanks guys for the reply. After reading a little I did conclude the same as you told me. I was getting worried for a min though. Still not impressed with the towing so far, maybe it will get better as I tow more.. hmm.. we'll see. .
What are the reccomneded upgrades and modification for towing. Trans cooler, etc...

Jason

[ScarabEpic22]

I have seen some other TB/Voy owners install the AirLift 1000 air bags and the Load Controlled 2 compressor for lifting the rear of the truck, and preventing it from sagging. Look here: http://www.truckworld.com/How-To-Tech/02-airlift-1000install/02-airlift1000.html Also, some people have installed aftermarket tranny coolers, and have had good luck. I am planning on doing these mods later this coming spring, after I have saved some $$ and can afford to do so. Also look here: http://chevytruckworld.tenmagazines.com/forums/topic.ten?id=73529 and here: http://chevytruckworld.tenmagazines.com/forums/topic.ten?id=84345

Hope this answers a few questions!