Lag!!!!!!!!!

SomeCrew · Post by **SomeCrew** » Fri Mar 11, 2005 4:03 pm

OK, here is how it goes, if I am already moving, and I break, release the break, and hit the accelorator, there is about a quarter to half second lag before the truck kicks....what could this be?

Post by **HenryJ** » Fri Mar 11, 2005 4:13 pm

The "infamous" torque reduction management feature.

Fry98 from the S10Forum.com: wrote:TQ Management is, in a nutshell, the computer pulling timing when you drive the truck hard. It also softens the WOT shifts. GM (and other manufacturers) use it to help the long term longevity of the vehicle.>>less warranty claims. The GM FS trucks are known for it...my truck has close to 300HP and if I try to spin 'em, it will do it for a second and then you can feel the motor fall on it's face. A good tune is my next mod. The aftermarket PCM companies (PCMForless, Westers, Nelson) will get rid of any % or all of TqM. If you get rid of 100%, it's a good idea to beef up your tranny w/ a cooler, shift kit and billet or Vette servo. It will help the longevity of the trans. and take full advantage of the tune.

rat from S10forum.com: wrote:Torque management is the way that your truck protects your transmission when it is shifting. It will retard the timing during a shift to limit the power output. Removing it will allow faster acceleration. Removing it could also wear your transmission out faster. The 4.3 is on the lower end of the power capabilitys on this transmisson, so it may be ok.

A search for torque management over there will yield lots of information.

SomeCrew · Post by **SomeCrew** » Fri Mar 11, 2005 4:23 pm

Thats cool and all, but it did not used to do it. It just started doing it, and I don't have be running the motor hard, i could be going 5mph and it will do it. Think it may be a slipping tranny?

Post by **HenryJ** » Fri Mar 11, 2005 4:35 pm

How many miles do you have on it?

I have 45k and have serviced the transmission twice. Filter and flush.

Might be worth doing?

SomeCrew · Post by **SomeCrew** » Fri Mar 11, 2005 4:37 pm

34K on mine.....ill get that done and see what happens, thanks

Post by **HenryJ** » Fri Mar 11, 2005 4:45 pm

There is a thread on servicing the transmission here somewhere.

Tip #1 don't use a prybar during the service.
#2 We have the deep pan
#3 The pan will come off without removing the crossmember or exhaust pipe.
#4 Use finesse , not force.
#5 Make sure you install it the right direction. Putting it on backwards can make a mess of things

Rusty · Post by **Rusty** » Fri Mar 11, 2005 5:13 pm

This almost sounds to me like the "dreaded 16mph neutral drop", as I call it. What my truck does is when I slow down to about 16mph and then accelerate again (like one would do going around a corner) it feels like the tranny is in neutral when I give it gas, the motor revs a bit and then the tranny clunks back into gear again. There was a similar thread somewhere here about it from maybe a few months ago. I think we decided it was irritating but "normal" for a least most of our trucks. I think someone was going to look into it but I never heard any more about it. I know I took my truck back to the dealer at least twice about it but they kept telling me they couldn't find a problem and I finally gave up and learned to live with it.

jeff024 · Post by **jeff024** » Fri Mar 11, 2005 7:16 pm

yup mine does it also mostly on cornering

SomeCrew · Post by **SomeCrew** » Fri Mar 11, 2005 9:14 pm

So I read about the corning thing you all said, went out and testing, sure 'nough it happens pretty much only there.

jeff024 · Post by **jeff024** » Sat Mar 12, 2005 4:19 am

I think its just the nature of the beast (crew cabs)

Rusty · Post by **Rusty** » Sat Mar 12, 2005 5:20 am

SomeCrew wrote:So I read about the corning thing you all said, went out and testing, sure 'nough it happens pretty much only there.

Actually, it will do it going straight too. Just slow down to the same speed and then accelerate again. I used to hit that spot all the time in bumper to bumper traffic. I hadn't driven my CC in a while (wife has been using it for commuting) so I had forgotten about it. First time I hit "the spot", I gave it so much throttle that the tires barked when it clunked back in gear (or whatever it's doing). Reminded me really fast!

F9K9 · Post by **F9K9** » Sat Mar 12, 2005 6:45 am

Has anyone, with HPP III tuning and the shift firmness option turned on, experienced the "lag" between 1st and 2nd?

Post by **HenryJ** » Sat Mar 12, 2005 7:18 am

f9k9 wrote:Has anyone, with HPP III tuning and the shift firmness option turned on, experienced the "lag" between 1st and 2nd?

I think the HPPIII must "lessen" the effect somewhat. I don't get the "lag" described as feeling like it slips or hits neutral.
I do feel the torque management though.

Adding the corvette servo helps that shift too. Mine is only a little weak on the third to overdrive shift while running the servo and shiftfirmness

F9K9 · Post by **F9K9** » Sat Mar 12, 2005 8:37 am

.

Adding the corvette servo helps that shift too. Mine is only a little weak on the third to overdrive shift while running the servo and shiftfirmness

That's one of my mods on the list. I know it is an easy mod for most but, I am not comfortable with the idea. There is a local shop that will do it for $70[/quote]

Post by **HenryJ** » Sat Mar 12, 2005 8:51 am

F9K9 wrote:
Adding the corvette servo helps that shift too. Mine is only a little weak on the third to overdrive shift while running the servo and shiftfirmness
That's one of my mods on the list. I know it is an easy mod for most but, I am not comfortable with the idea. There is a local shop that will do it for $70

You know that means they get $53 for the install, right? I bet if you buy the kit and supply the $53 in beer your friend will help with the install during the bodylift trip.
It really is easy to do, just hard to access. During or after the bodylift it is not nearly as bad.
Read up on the topic and jump in with both feet. What's the worst that can happen? Totally mess up the transmission?

F9K9 · Post by **F9K9** » Sat Mar 12, 2005 12:25 pm

HenryJ wrote:
You know that means they get $53 for the install, right? I bet if you buy the kit and supply the $53 in beer your friend will help with the install during the bodylift trip.
It really is easy to do, just hard to access. During or after the bodylift it is not nearly as bad.
Read up on the topic and jump in with both feet. What's the worst that can happen? Totally mess up the transmission?

If "Top" would accept payment AFTERWARDS I might consider it

Otherwise with that much beer, Top won't be allowed within a county of my CC

top_sgt · Post by **top_sgt** » Sat Mar 12, 2005 12:35 pm

all this "lag" in shifting reminds me of the "GM slush-box" tranys!!!

and reed.......i work, then drink!! never drink and work!!

afraid i might "break" something.........like me!!!!

so.....bring the kit and we'll install it when we do the BL!!!!!

Post by **HenryJ** » Sat Mar 12, 2005 1:19 pm

top_sgt wrote:.....bring the kit and we'll install it when we do the BL!!!!!

Print out the thread. There are some helpful tips in there, also print out the instructions from that website. The pictures help to explain the process.

top_sgt · Post by **top_sgt** » Sat Mar 12, 2005 1:54 pm

thanks HenryJ!!

F9K9 · Post by **F9K9** » Sat Mar 12, 2005 2:41 pm

top_sgt wrote:thanks HenryJ!!

Get your printer warmed up 'cause I am tired of chasing threrads on the servo mod "Mr Mechanic"

kf6kmx · Post by **kf6kmx** » Sat Mar 12, 2005 10:14 pm

Rusty wrote:
SomeCrew wrote:So I read about the corning thing you all said, went out and testing, sure 'nough it happens pretty much only there.
Actually, it will do it going straight too. Just slow down to the same speed and then accelerate again. I used to hit that spot all the time in bumper to bumper traffic. I hadn't driven my CC in a while (wife has been using it for commuting) so I had forgotten about it. First time I hit "the spot", I gave it so much throttle that the tires barked when it clunked back in gear (or whatever it's doing). Reminded me really fast!

Yep, on the way to work at the base every morning I take the back roads as far as I can before getting into the nutz traffic.. There is one signal light just as you leave town that almost always catches me just right to make it do it.. Just about the time I'm down around 10-15, it turns green.. If I'm not thinking about it, I end up hitting the gas hard and it jumps pretty good..

I have noticed once time it seemed to do it in 4hi.. That was a little more disconcerting having the trany 'slip' while offroad in 4x.. Didnt help the nercves any that I was making a turn uphill when it did it, gentle hill, but a steep drop off about 15ft behind me as I made the turn.. Came to an almost complete stop before it 'grabbed a gear' again.. Was doing about 15 or so up a switchback on the hill (no steeper than a steep grade onramp to the freeway), in 4hi; let off the gas a little in the tight part of the turn, truck slowed to about 10, hit the gas and it did the slip-and-grab stunt..

1337vending · Post by **1337vending** » Sun Mar 13, 2005 4:34 pm

Rusty wrote:
SomeCrew wrote:So I read about the corning thing you all said, went out and testing, sure 'nough it happens pretty much only there.

Actually, it will do it going straight too. Just slow down to the same speed and then accelerate again. I used to hit that spot all the time in bumper to bumper traffic. I hadn't driven my CC in a while (wife has been using it for commuting) so I had forgotten about it. First time I hit "the spot", I gave it so much throttle that the tires barked when it clunked back in gear (or whatever it's doing). Reminded me really fast!

I've noticed the same thing with my truck, although it seems to have something to do with how fast you apply the throttle. It seems be a lot worse if I get on the gas quickly out of a turn at ~16mph. The transmission seems to alter its shifting based on how quickly you apply the throttle...e.g. when I'm driving along at 45-50 mph in overdrive and ease into the gas about 1/2 way, the transmission stays in overdrive with the torque converter locked up. But if I give it the same 1/2 throttle all at once the torque converter unlocks and the trans downshifts into 3rd. Heckuva lot better than the Ford transmissions though...

Rusty · Post by **Rusty** » Sun Mar 13, 2005 6:51 pm

I don't know if this will add to understanding the problem or add to the confusion. Anyway, I also noticed that if I carefully watch the tach as I'm slowing down (like coasting up to a light) I can see the tach jump up slightly right about at that 16mph mark. It's almost like the computer/tranny is programmed to downshift at that speed and suddenly hitting the throttle "confuses" it and sends it scrambling for a gear to go into. Meanwhile the rpms are picking up so when the tranny does go into gear, you get the nice jolt we are experiencing.

I guess what I'm trying to say (and I'm getting pretty tired - it's been a long day) is maybe this is a computer or firmware problem and not really with the tranny itself. Does this make sense to anyone? If it is a computer problem, I wonder if GM has a firmware upgrade for it that they aren't telling anyone about?

1337vending · Post by **1337vending** » Sun Mar 13, 2005 8:01 pm

I agree with what Rusty is saying, since our transmission is the 4-L60E (E being for electronically controlled, im pretty sure). Especially since we can change our WOT shift points with the HPIII, which interfaces with the computer and not the transmission.

I'm looking at my GM Helm Service manual right now and the transmission/computer determines when to shift using % of TPS and transmission output shaft RPM, so I'm thinking that it downshifts ~16mph like Rusty said.

Hopefully that made sense...

coreylubahn · Post by **coreylubahn** » Mon Mar 14, 2005 7:09 am

I can guarantee you that it does downshift at or around that speed...now that I have my exhaust work done I can hear the exhaust get louder as I starting to break at stop signs and the such, exactly as if it just downshifted. I would guess that if you gunned it at that point that the computer could very easily get confused.

Rusty · Post by **Rusty** » Mon Mar 14, 2005 7:17 am

coreylubahn wrote:I can guarantee you that it does downshift at or around that speed...now that I have my exhaust work done I can hear the exhaust get louder as I starting to break at stop signs and the such, exactly as if it just downshifted. I would guess that if you gunned it at that point that the computer could very easily get confused.

Actually, you don't even have to "gun it". Mine does it with even mild throttle. It's like the computer says "Hey, wait a minute. I thought we were stopping!" and then sort of freaks out for a second. I know that's not exactly a scientific explanation but it's about as accurate as I can get in the morning.

killian96ss · Post by **killian96ss** » Mon Mar 14, 2005 8:49 am

All of the problems mentioned in this post can be corrected with a Transgo shift kit. My SS with the same 4L60E used to have all the same problems, but after installing the kit my tranny upshifts and downshifts much nicer with no lag, slip or hard clunking engagement. This would be a good mod to do after your warranty expires since it will void any transmission work. BTW any transmission mods including the Corvette servo will void your transmission warranty.

Steve

Rusty · Post by **Rusty** » Mon Mar 14, 2005 11:34 am

killian96ss wrote:All of the problems mentioned in this post can be corrected with a Transgo shift kit. My SS with the same 4L60E used to have all the same problems, but after installing the kit my tranny upshifts and downshifts much nicer with no lag, slip or hard clunking engagement. This would be a good mod to do after your warranty expires since it will void any transmission work. BTW any transmission mods including the Corvette servo will void your transmission warranty.

Steve

My warranty is LOOONNNGGG gone! I actually bought the Corvette servo to put in my crew, then saw what I had to do to install it (I don't have a body lift - no room to work). The kit is still sitting in my toolbox. I have thought about the Transgo kit but for now I've just learned to live with the weird shift thing. For the moment, I'm concentrating my efforts on trying to get my Blazer running.

killian96ss · Post by **killian96ss** » Mon Mar 14, 2005 6:11 pm

Rusty wrote:I actually bought the Corvette servo to put in my crew, then saw what I had to do to install it (I don't have a body lift - no room to work).

The BL would definitely give you enough room to work with. I had to lower the tranny in my SS to install a new 2nd. gear servo. The Transgo kit is the best one I've seen for the 4L60E. It even comes with a new 2nd. gear servo correction kit (similar to the Corvette servo).

I have thought about the Transgo kit but for now I've just learned to live with the weird shift thing.

If you ever do the Transgo kit, I would be glad to help with any questions you might have. The kit will take almost a full day to install, but it is well worth it. The Hypertech shift firmness option doesn't even compare to the quality of shifts you get with the Transgo kit.

As soon as my warranty expires, this will be the first mod I do.

Steve

Rusty · Post by **Rusty** » Mon Mar 14, 2005 7:08 pm

I just sent out the 700R4 from my Blazer to get rebuilt. The guy that's doing it works together with his wife rebuilding engines, transmission, you-name-it. They also work on airplanes - interesting. Anyway, he's been rebuilding auto trannys since there first were auto trannys and supposedly knows every nut and bolt and spring and valve, etc, in every auto transmission ever made (according to everyone I've talked to) so it should be interesting to see what I get back. I told him I planned to tow with it and needed "heavy duty" and he said he'd fix me up.

The only problem with these two is they are obviously up there in years and don't work very fast so it may take me 6 months to get my tranny back. That's Ok. It'll take me 6 months to figure out how to pay for it!

That'll take care of the engine and tranny. Now I got to figure out the tcase!

Post by **Walt** » Sat Mar 19, 2005 1:07 pm

Rusty wrote:It's like the computer says "Hey, wait a minute. I thought we were stopping!" and then sort of freaks out for a second.

Rusty · Post by **Rusty** » Sat Mar 19, 2005 7:19 pm

wamason wrote:
Rusty wrote:It's like the computer says "Hey, wait a minute. I thought we were stopping!" and then sort of freaks out for a second.

Like I said, that was about the best explaination I could come up with.