Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

1 - 20 of 27 Posts

·
Registered
Joined
·
56 Posts
Discussion Starter #1
Fellow SuperSporters... Let me preface my post with how pleased I am with my Vector Tune. I have said it all over this forum and this little hiccup won't change my thought on the value of this mod. I have, however, discovered one little, um, inconvenience, if you will. I expect that Chris will respond but I want a lot of feedback from my fellow Vector Tuners which is why I posted here and not the Vector section.

Say I'm cruising along steady at 40 mph, 20% throttle. If I crack it wide open, there is a noticeable delay, borderline confusion in how my SS responds, specifically what gear choice it wants to make. Don't get me wrong, once it figures it out that I want to go fast, it does not disappoint, but this lag is kind of a bummer. If I am in the throttle from the line or under slight acceleration to full throttle, it doesn't do it. It only seems to be from a steady speed to WFO.

I promise I am not being critical, it is noticeable. The first time my wife experienced it, she thought something was wrong the truck. Anyone out there experience this? I looked around the forum last weekend and I have a K&N so I thought maybe cleaning the MAF was my answer, but it doesn't seem to have solved the issue. :worried:

Thanks to all.

P.S. I have seen from time to time some Vector rants, and I don't want this to be misconstrued or turn into a Vector rant. There is nothing I like more than pulling up next to a Mustang, Camaro, Ricer, Lightning etc. in the gotta-merge lane and politely saying "Spank you very much."
 

·
Registered
Joined
·
38 Posts
I will try to duplicate with my truck. I will data stream to see exactly what is happening.
A couple things come to mind,
1. The 1st gear downshift cut-off is oddly enough 40-42MPH, so you may be right in your theory that the truck is confused. This would also happen in a stock truck (just at a lower MPH)
2. The electronic throttle controller is a little slow at times which adds to a feeling of hesitation.
There may not be a fix for this problem. I will duplicate the problem with my truck returned to stock also.
I will post the results.
Kirk
 

·
Registered
2006 chevy
Joined
·
1,966 Posts
I know quite a few trucks did that stock, I've seen a few local guys do that and some other wierd stuff stock.

On those trucks our tune fixed the issue but of course we'll look into it :)

BTW for issues like this its just best to PM/Email/Call us first, we have some pretty good troubleshooting ideas to start with first as well as user data/reports.

So far 100% of cases involving wierd transmission behavior were fixed cleaning the MAF a few times. It seems K&N really went heavy on some of these things, we've had trucks that were fine for 1-2 miles after cleaning and then needed to be cleaned again lol!
 

·
Registered
2006 buick
Joined
·
171 Posts
Now that I've been driving mine for about 1000km, while I still love every second, I do have one issue which is really starting to bother me in a big way. Firstly, My TBSS is still completely stock. Secondly, at 1000km it's barely broken in. Thirdly, I usually have traction and stabilitrack off. My problem like others is rapid throttle position response. If you bury the loud pedal to pass someone I end up with the rpm's shooting up with no change in forward speed for an appreciable time (almost got rear ended yesterday) :( . If you do the same maneuver while rolling on the throttle the truck will scare most passengers :D

So what's with that? Is it possible that there's something in the tranny code that stops it from dropping to a lower gear if the throttle position changes too quickly. This only happens while moving and doesn't seem to be an issue from a stopped position.

Chris... any ideas?
 

·
Banned
Joined
·
195 Posts
A tune and an aftermarket torque converter will change that. Tune has made a huge difference on my SS. Missing out if you dont have it... Rpms wont dip as much between gears with a torque converter. Will keep the rpms more in the sweet spot so you can get her moving quickly...:D Good choice on color also
 

·
Registered
2006 buick
Joined
·
171 Posts
tBSSOldblue said:
A tune and an aftermarket torque converter will change that. Tune has made a huge difference on my SS. Missing out if you dont have it... Rpms wont dip as much between gears with a torque converter. Will keep the rpms more in the sweet spot so you can get her moving quickly...:D Good choice on color also
But... it seems that some are having the same problem even with a tune :eek:
In the very near future I'm planning to do the tune, CAI (when Chris has them available), and a converter (3200-3600rpm... not sure how high I want to go). But this rather bizarre behavior is worrying me a little :(

Blue definitely rocks... :yes: :thumbsup:
 

·
Registered
2006 chevy
Joined
·
204 Posts
I don't think this is a problem with the tranny or stock tune or VCM tune.

Here is what is happening.

You are in say, 3rd or 4th at about 1700 - 2100 RPM @ 38-41 MPH.

You floor it and the transmission grabs 3 - 2 - 1 or 2 - 1 or for sake of argument, goes directly to 1st. The engine needs to spin up to about, oh 5700 - 5900 RPM from 1700 RPM.

This takes time and is what you are feeling. I'm guessing the flywheel and the like on this engine aren't exactly vette light and this is what everyone is feeling. When the engine hits the speed of the transmission so to speak, you feel the acceleration.

That's my take on it.
 

·
Registered
Joined
·
2,026 Posts
you're pretty good in getting the truck to behave in a way that 8 out of 10 of us could never do...right in that "no man's land" and you say your wife got it to happen as well?? any vehicle will do that given you are right at the "max" rpm for a lower gear...I've done it in my work car numerous times at 35mph & 75mph, granted I am pounding on my work car probably 10-15x a night, so the odds are increased that I will have that situation a couple of times..now that you know where the threshold is for the 2 to 1st downshift try easy the pedal down taking about a full second to lower the hammer, bet you don't have anymore issues..
 

·
Registered
Joined
·
107 Posts
My truck does the same thing , if I punch it at 40 it just revs , then starts to pull , does the same thing around 60mph , I have the Vector tune . I also heard some detonation today with the warmer temps here in the Northeast :worried: , and I don't think it's the gas I'm using , I've been using Shell 93 from the same station for the last two months .
 

·
Registered
Joined
·
56 Posts
Discussion Starter #12
TonyGXP said:
you're pretty good in getting the truck to behave in a way that 8 out of 10 of us could never do...right in that "no man's land" and you say your wife got it to happen as well?? any vehicle will do that given you are right at the "max" rpm for a lower gear...I've done it in my work car numerous times at 35mph & 75mph, granted I am pounding on my work car probably 10-15x a night, so the odds are increased that I will have that situation a couple of times..now that you know where the threshold is for the 2 to 1st downshift try easy the pedal down taking about a full second to lower the hammer, bet you don't have anymore issues..
The point is though, my Silverado SS doesn't have this problem and I don't want this problem on my TB either. I don't want to have to ease in to it. I mentioned in my post that I observed a steady opening solves the issue so I know that is a work-around but that still sux. I want to drop the hammer and hope that I am pointed in the right direction. And, based on comments, I'm not sure that it has anything to do with the tune either, to Kirks point on Page one. Maybe the tune just moves it to a different spot. I only had 700 miles on my TB when I put the tune on it, most of which was spun by my wife and none of which was at full throttle, so I don't have a lot of pre-tune experience. I am anxious to see what Kirk's findings are.
 

·
Registered
Joined
·
38 Posts
steined said:
I don't think this is a problem with the tranny or stock tune or VCM tune.

Here is what is happening.

You are in say, 3rd or 4th at about 1700 - 2100 RPM @ 38-41 MPH.

You floor it and the transmission grabs 3 - 2 - 1 or 2 - 1 or for sake of argument, goes directly to 1st. The engine needs to spin up to about, oh 5700 - 5900 RPM from 1700 RPM.

This takes time and is what you are feeling. I'm guessing the flywheel and the like on this engine aren't exactly vette light and this is what everyone is feeling. When the engine hits the speed of the transmission so to speak, you feel the acceleration.

That's my take on it.
I have found that this is what is happening.
When you are driving at 40mph you are in 3rd gear. You are also at the top limit of where a 1st gear downshift will take place.
When you hammer the gas the engine has to downshift from 3rd to 1st and the engine has to go from 1500 rpm to over 5000 rpm. This is the delay you feel. This also happens on a stock calibration. You can feel it slightly more with the tune because we raise the upper limit on the downshift causing the engine to have to spin higher.
Kirk
 

·
Registered
Joined
·
2,026 Posts
Vector MS said:
I have found that this is what is happening.
When you are driving at 40mph you are in 3rd gear. You are also at the top limit of where a 1st gear downshift will take place.
When you hammer the gas the engine has to downshift from 3rd to 1st and the engine has to go from 1500 rpm to over 5000 rpm. This is the delay you feel. This also happens on a stock calibration. You can feel it slightly more with the tune because we raise the upper limit on the downshift causing the engine to have to spin higher.
Kirk
and that's the point, any car/truck will do this, just has to be at the right speed for the particular vehicle, when you try to make it happen..
 

·
Registered
Joined
·
56 Posts
Discussion Starter #15
While I intend to accept this as the explanation, I would like to go on record to Chevrolet that I think this is lame. My Silverado SS doesn't do it and I will continue to believe this shouldn't either. Right after GM and Delphi figure out if they will still be in business next year, I expect them to get right on this issue. :laugh:

BTW, I'm still going to tinker with it at different speeds to see if it happens anywhere else.
 

·
Registered
2006 chevy
Joined
·
616 Posts
I tried this test a couple times this morning on my way back from a meeting. I have a stock tune (stock everything, actually).

When cruising at 40 mph, if I floor it, it only goes into 2nd gear not first. So I don't have this problem at this speed.

Now that I've read this thread, I will try the same thing at incrementally lower speeds (i.e. 38 mph, 36 mph) sometime this weekend.
 

·
Registered
2006 chevy
Joined
·
204 Posts
The SSS has a 4L80 right? Different gear ratios right? So the feel will be different. Look at the gear spread on the 4L70 we have. Not exactly tight and part of the reason there is a 4.10 back there...

Not saying it is ideal, but it isn't a problem per say.
 

·
Northwest Chapter
Joined
·
11,824 Posts
gunner said:
I'm pretty sure the SSS is a 4L65E.
Thats what I remember hearing too, it is a 4L60E tranny beefed up (like the TB SS 4L70E) but not as beefy as the 4L70E TB SS tranny. As for rear gears, I have no idea, but I bet they are at least 3.73s.:m2:
 

·
Registered
Joined
·
143 Posts
EssEss said:
Say I'm cruising along steady at 40 mph, 20% throttle. If I crack it wide open, there is a noticeable delay, borderline confusion in how my SS responds, specifically what gear choice it wants to make. Don't get me wrong, once it figures it out that I want to go fast, it does not disappoint, but this lag is kind of a bummer. If I am in the throttle from the line or under slight acceleration to full throttle, it doesn't do it. It only seems to be from a steady speed to WFO.
My GTO does this but not as bad as my dads Silverado SS. Both of them have stock tunes on them. I was told that if you have it in "3" it doesnt do it because all it does is realease a clutch pack or something to that effect.

Also on the issue of pining, my dads Silverado SS does it terribly and like I said, its totall stock. The thing sounds like its going to blow itself to pieces and it doesnt stop until you lift off the gas. We took it to the dealer and they dont hear anything :weird:. O well, it should be much longer until its traded in for a TBSS :raspberry
 
1 - 20 of 27 Posts
Top