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Hello. I am new to having a car with an electronic throttle. My former car was a 2002 cavalier z24. I now have the malibu ltz and I do love it. However I noticed that once I am over 40mph I have to push down the accelerator a lot harder to get it to respond. I can actually push it some and it does not respond at all. Once it does respond it is all of a sudden and it really goes. Is this normal for this type of throttle or is my car messed up? I haven't had any other problems with it. This issue is exceptionally bad if I am going uphill. maybe the transmission??
 

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Hello. I am new to having a car with an electronic throttle. My former car was a 2002 cavalier z24. I now have the malibu ltz and I do love it. However I noticed that once I am over 40mph I have to push down the accelerator a lot harder to get it to respond. I can actually push it some and it does not respond at all. Once it does respond it is all of a sudden and it really goes. Is this normal for this type of throttle or is my car messed up? I haven't had any other problems with it. This issue is exceptionally bad if I am going uphill. maybe the transmission??
when it finally responds, do you feel a downshift? The shift logic on this 6 sp. tranny (that is if yours is a 6 speed) changes once you over certain speed. I believe the particular speed may even be mentioned in the manual. Below that speed the shifts are livelier, but above you get into the different logic that has been criticized by many people here. I personally don't think it's that bad though, mine is a V6 and there's enough juice in that motor to accelerate moderately without a downshift and significant revving up. Which can feel weird at first until you realize that you are accelerating even though the car stays quiet...
 

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Most of the time when I'm driving my pedal is touching the floor.

I love having the V6
 

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Most of the time when I'm driving my pedal is touching the floor.

I love having the V6
im the same way!!!!!!!!!!!!!!!.... - the v6 :(

o well springs almost here time to get the GTP out :)

BTW my uncle is on a TBSS ( trailblazer ss) forum and they have the same problem...
apparently bending this thing under the gas pedal helps a lot.... wonder if its the same on our cars?
 

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these cars, especially the 3.6/6 speed, have a lot of logic that it is processing at throttle variation. when you push the throttle at cruising speeds, the computer monitors how fast the throttle was depressed, how far it was depressed, vehicle speed, transmission torque load, engine output load, ambient conditions, etc etc. now remember that on these engines, you have variable valve timing. the computer uses multiple algorythms to determine how far to advance or retard all 4 cams, plus which gear to be in, how far to advance timing, how much injector pulse width, fuel pump pressure (yes its variable on these), and to top it all, its fly-by-wire. this stuff takes time to compute. however, if you want to see the processing power on this thing, drive steadily at 45mph, and mash the throttle to the floor as fast and hard as you can. youre going to say, wow, is this a four door sedan??? compare to how it responds when you dont mash it fast and hard and youll see the difference. the computer senses an urgency to get that car moving depending on throttle position and speed of request. its pretty interesting stuff.
 

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With the electronic throttle there's a bit of a disconnect in feel compared to a car with a throttle cable, this is the nature of the beast on throttle by wire and a quirky one at that.

Ummmmm...no!

The electronic throttle has nothing to do with the "disconnect in feel" you have. It is all in the tuning of the ECM and the TCM. The throttle inputs are so precise, if you remove that "disconnect feel" you get a very touchy and unsafe vehicle. Add in the fact that GM throws in a massive amount of torque management to idiot proof your vehicle, and you can start to see why the "disconnect feel" is so apparent in the vehicle you are driving. It has nothing to do with the fact that the throttle is electronic instead of mechanical, it has to do with how the electronic signal is interpreted by the computers in your vehicle.
 

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these cars, especially the 3.6/6 speed, have a lot of logic that it is processing at throttle variation. when you push the throttle at cruising speeds, the computer monitors how fast the throttle was depressed, how far it was depressed, vehicle speed, transmission torque load, engine output load, ambient conditions, etc etc. now remember that on these engines, you have variable valve timing. the computer uses multiple algorythms to determine how far to advance or retard all 4 cams, plus which gear to be in, how far to advance timing, how much injector pulse width, fuel pump pressure (yes its variable on these), and to top it all, its fly-by-wire. this stuff takes time to compute. however, if you want to see the processing power on this thing, drive steadily at 45mph, and mash the throttle to the floor as fast and hard as you can. youre going to say, wow, is this a four door sedan??? compare to how it responds when you dont mash it fast and hard and youll see the difference. the computer senses an urgency to get that car moving depending on throttle position and speed of request. its pretty interesting stuff.
Do you happen to know the reason for the 6-4 shift on highway speeds? It's hard to get it to kick down to 5th, it either stays on 6th or goes to 4th and takes off. In many cases 5th would be adequate but there doesn't seem to be a reliable gas pedal input I can use specifically to go to 5th. It's not too bad, but it can be a little better.
 

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I fixed the 6-4 shift problem and the slow response at 40mph tonight.

6-4 was programed at 54mph in the tcm for both the 6-5 downshift and the 5-4 shift. I raised the mph on the 6-5 so it goes to 5th....then 4th if you press the throttle more.


40 mph slow response is due to the trans shifting to 5th gear at 38mph. The rpm is very low and thee is no response. I changed the shift mph so the trans holds third and fourth longer. Problem solved. I need to toy with converter lock speeds in third gear to complete the feel I want, but it is going well so far.
 

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I fixed the 6-4 shift problem and the slow response at 40mph tonight.

6-4 was programed at 54mph in the tcm for both the 6-5 downshift and the 5-4 shift. I raised the mph on the 6-5 so it goes to 5th....then 4th if you press the throttle more.
Cool...I wish I had the scanner tool to do that.

Wonder what's GM reasoning to program it like that.
 

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I fixed the 6-4 shift problem and the slow response at 40mph tonight.

6-4 was programed at 54mph in the tcm for both the 6-5 downshift and the 5-4 shift. I raised the mph on the 6-5 so it goes to 5th....then 4th if you press the throttle more.


40 mph slow response is due to the trans shifting to 5th gear at 38mph. The rpm is very low and thee is no response. I changed the shift mph so the trans holds third and fourth longer. Problem solved. I need to toy with converter lock speeds in third gear to complete the feel I want, but it is going well so far.
GM needs more people like you to tune their cars.

The v6 may be better in these shift situations but as stated before, the 4-banger is a joke - basically no power above 50mph.

The Cobalt 4 speed is much better and responsive.
 

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I wonder if the vibration issue can be fixed by custom recalibration :)
 

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there is a certain amount of throttle that can be depressed to attain a 6-5 downshift, but it also depends on load and ambient conditions. you have to remember that these cars are tuned for fuel effieciency, not balls out performance. they have to abide by CAFE standards. there are ways to tune the transmission shift adapt timing sequences, but you sacrifice fuel economy, and you also have to remember that computers are stupid, they can only read 1's and 0's. they abide by tuning specifications. if you change the parameters, you effectively override the factory torque limiting system and now make the very expensive 6t45 transmission sucseptible to damage. the factory tuning is more than adequate, you just have to push the throttle a little harder and faster to attain what you want. in the old days where you had a TV cable attached to the transmission pressure governor from the throttle bracket, it was easy to manually make the transmission shift in accordance with throttle input. today, its all for emissions. if you want go, you have to mash. the other thing you have to remember, is that it might be going into 5th gear, but you cant notice the shift due to load condtions, and the reason it feels like its staying in 6th gear is because the car is also utilizing cam timing. you have 4 cams that can vary 25 degrees + or - static TDC to attain whatever driving and loading conditions the driver inputs to the ECM. when it feels like its staying in sixth, its downshifting to 5th, but you cant notice it because it has now retarded the exhaust cams and advanced the intake cams to provide for greater valve overlap in an attempt to retain fuel economy. when you push harder on the throttle, cam phasing then will change to a performance standard and advance the exhaust cams and retard the intake cams to reduce valve overlap and increase cylinder pressure to increase performance and now fuel economy goes out the window. well, i hope that helps you all a little bit. and one more thing, if you decide to retune the ecm in these cars, and you override the torque limit system, and you break the transmission, and you take it to the dealer, and they check for failure records, and they see the tuning calibration has been changed..........your warranty goes out the window. gm will say, go pound sand, and then put a warranty block on your 100k warranty that you paid for when you bought the car. that warranty block shows up on gm's VIS website and no dealer in the country will warranty anything on your car at that point. so dont do that unless youre rich and dont care about warranty.
 

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Even if there is a way to get 6-5 it is hard to accomplish, instead most of the time instead of 6-5 6-4 happens and I have to immediately ease off and then it goes to 5th. Most of the time all I need is 5th but instead I get 6-4 and too much acceleration (or no shift and not enough acceleration)...not sure how that saves gas.

I think if the the 6-4 happened a bit lower in the pedal travel allowing more space for a reliable 6-5 shift it would be better. At 60 mph 4th makes the rpm to just above 3000 which is pretty much the max torque rpm for the 3.6. This engine is strong and it pulls hard...too hard for what I am trying to do and there's no easy pedal input for less aggressive take off.

I just don't need the oomph the 6-4th delivers most of the time. I want to be able to do 6-5 easily as opposed to 6-4 + 4-5 sequence. I have been driving the car since last September and I still can't achieve a reliable 6-5. I can only do it sometimes.

On my Accord that I drove before (5 speed auto) dropping one gear down was easy to achieve and it was just what I needed for highway merging. Malibu is not bad, but I think GM can make it even better. I am talking about extra finesse that will make this powertrain absolutely awesome not merely 'good' or 'adequate'.
 

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well to me it sounds as though youre describing adverse load conditions such as on uphill terrain or perhaps something else. the other thing is that i see youre in canada. im not sure if these cars are built differently for canadian application or not, but im pretty certain i know which sensation of low throttle response youre talking about, and when i drive mine, it seems normal.
 

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well to me it sounds as though youre describing adverse load conditions such as on uphill terrain or perhaps something else. the other thing is that i see youre in canada. im not sure if these cars are built differently for canadian application or not, but im pretty certain i know which sensation of low throttle response youre talking about, and when i drive mine, it seems normal.
I am talking about regular highway driving on flat terrain with one 160 lb guy as a driver and a small lunchbox in the trunk. No extra load whatever :) The behavior is there most of the time on flat Toronto area highways.

I am not saying it's not normal...I don't have a big problem driving like that, it just seems not optimal.

Why a Canadian vehicle would be any different?

BTW, I believe others commented on this behavior here on the forum.
 

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According to what Bobo said above it might be a simple tweak:

"6-4 was programed at 54mph in the tcm for both the 6-5 downshift and the 5-4 shift. I raised the mph on the 6-5 so it goes to 5th....then 4th if you press the throttle more."

That's the behavior I would prefer.
 

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well im not sure what else to say. i was just brainstorming to try to help. i know how the shift adapt logic is designed on these cars, and i assure you it is for fuel economy. whether or not there is a difference for canadian models or not, i dont know for sure, it was just something to throw out there. there are some differences from canadian to us models of other lines and that applies to local and federal motor vehicle laws, and it also applies to differing emission standards, so it was just a thought. now like i said, as far as messing with shift timing logic in the computer, youre risking the tranny when you get into that. it does things the way it does for not just emissions but for elongating the life of the transmission. it is your car, do what you wish, but be aware that when it breaks, no dealer will touch it due to the unfamiliar software that will be stored in the ecm.
 

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well im not sure what else to say. i was just brainstorming to try to help. i know how the shift adapt logic is designed on these cars, and i assure you it is for fuel economy. whether or not there is a difference for canadian models or not, i dont know for sure, it was just something to throw out there. there are some differences from canadian to us models of other lines and that applies to local and federal motor vehicle laws, and it also applies to differing emission standards, so it was just a thought. now like i said, as far as messing with shift timing logic in the computer, youre risking the tranny when you get into that. it does things the way it does for not just emissions but for elongating the life of the transmission. it is your car, do what you wish, but be aware that when it breaks, no dealer will touch it due to the unfamiliar software that will be stored in the ecm.
I am not going to do anything, it's not bad the way it is, not to mention that I don't have the tools and tuning experience. Generally speaking I'd like to get into tuning, but as usual with modding there's certain amount of risk, as you rightly mentioned. I am sure there are safe things that can be done, but it takes research and experience, plus I am not prepared to deal with my dealer refusing legitimate warranty claims on the basis of my modifications, which, with my luck, surely will happen :)

To be fair there might be another consideration here. The thing is that even on 6th there's a fair amount of juice to move the car. In fact, we could be looking at a user interface issue...We normally looking to feedback to our inputs and when it downshift it provides that feedback...But if you press the pedal but do no hear or feel any immediate effect it may be confusing. Mild acceleration itself is not that easy to detect if you're not watching the speedometer. This is similar to the "rubber band feel" that owners of CVT equipped cars note often. Some people flat out hate CVT because of that.

So, functionally, the tranny might be doing a somewhat reasonable thing here. It's just not as user friendly as it could be.
 
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