Part throttle downshifts

R

rooter

LVC Member
Joined
Oct 15, 2005
Messages
42
Reaction score
0
Location
SoCal
Did a search on "downshift" and "transmission" and couldn't find anything on this.

I just picked up my '06 a few days ago and one thing I've noticed so far is the tranny seems resistant to kicking down with part throttle application. For example, after rolling through a low-speed turn at an intersection, if I push the accelerator moderately I can hear the engine kind of bogging/lugging. I know lugging is the kiss of death for a fresh engine, so I either have to granny it or jump on it a little to force a downshift...which will get old after awhile.

Anyone else have similar experiences?

From a standing start, everything is fine--part throttle shifts are nice and crisp. I like to redline 1st and 2nd once per hundred miles for the first 1,000 miles on a fresh engine and the one full throttle blast I've done so far was great!
 
rooter said:
Did a search on "downshift" and "transmission" and couldn't find anything on this.

I just picked up my '06 a few days ago and one thing I've noticed so far is the tranny seems resistant to kicking down with part throttle application. For example, after rolling through a low-speed turn at an intersection, if I push the accelerator moderately I can hear the engine kind of bogging/lugging. I know lugging is the kiss of death for a fresh engine, so I either have to granny it or jump on it a little to force a downshift...which will get old after awhile.

Anyone else have similar experiences?

From a standing start, everything is fine--part throttle shifts are nice and crisp. I like to redline 1st and 2nd once per hundred miles for the first 1,000 miles on a fresh engine and the one full throttle blast I've done so far was great!
Click to expand...


Owners manual says the tranny needs a few hundred miles to "learn" how you drive and how its own internals are working (drag, etc). Sounds like that is your issue.

Leave it in SST/3rd to keep the revs up (not too far up though for break-in).
 
Thanks. I hope it "learns" how to downshift more appropriately. Upshifts are crisp and not overly jerky or anything.

...oh BTW, according to the manual, it I leave it in SST/3rd, it'll start off in 3rd (same with 2nd). Would be good for starting off in the snow... 4th starts off in 1st and then holds 4th. I don't mind using the manumatic every now and then--I'd use it more if it knew how to match revs on downshifts though...
 
there are no "revs to match" on this transmission since there's no clutch for you to use. shift at normal speeds and the electronic throttle control will make sure everything's in order.
 
I'm not sure if it's the best idea to redline the car within the first 1,000 miles. Supposedly there will be a lot of metal etc. in your oil since the new motor is being broken in. I thought the magic number was 1,500, I could be wrong.
 
I've heard you should give it a good break in too but have also heard that nowadays breaks arn't fully necessary. I know when I got my '03 cavalier new w/ like 100 miles I did get on it(manual) a couple of times and when it came time for an oil change I requested them to check the oil and what not for them metal shavings and they reported clean oil, almost like it just went in.

But taking it easy for the first 1,500 mi's or so is not a bad idea. Besides, why go too fast, no one can check your sweet ride out if you fly by :).
 
beaups said:
...shift at normal speeds and the electronic throttle control will make sure everything's in order.
Click to expand...
Interesting. Say you're going hot into a corner and you're going to drop a couple of gears to set up for the exit; if the engine braking is too sudden and jarring the rear end could step out. With the drive-by-wire system one would think the engine management system could control the throttle in such a way that the engine braking is more seamless instead of just bam, dumping it into the lower gear. Is this what you mean?
 
yes this is what I mean. As long as you are applying any throttle (even very light) the downshifts are quite smooth. If you're breaking and say suddenly slowing down to make a corner and shift from 4 to 1 it will grab a little but not enough to get squirrely. Additionally, the shifts can be quite delayed so it takes a little getting used to so you can get the timing right. Go out and play around with it. You're not going to hurt anything. The car won't let you.
 
KD00LS said:
I'm not sure if it's the best idea to redline the car within the first 1,000 miles. Supposedly there will be a lot of metal etc. in your oil since the new motor is being broken in. I thought the magic number was 1,500, I could be wrong.
Click to expand...
I just do it once per 100 miles for the first 1,000 miles to help seat the rings. Just an old, perhaps antiquated habit I guess. But make no mistake: lugging is FAR worse on an engine than revving it, at any age, but especially on a fresh engine.

I'm hearing more and more new engines don't need a break-in oil change at 500 miles. Makes sense to me if they're running synthetic from the get-go, otherwise the rings might not ever seat fully.
 
beaups said:
yes this is what I mean. As long as you are applying any throttle (even very light) the downshifts are quite smooth. If you're breaking and say suddenly slowing down to make a corner and shift from 4 to 1 it will grab a little but not enough to get squirrely. Additionally, the shifts can be quite delayed so it takes a little getting used to so you can get the timing right. Go out and play around with it. You're not going to hurt anything. The car won't let you.
Click to expand...
Got it. Definitely will play with it. Still bedding in the brakes too though, so can't go diving into corners yet :)
 
if you don't like "lugging" you really need to use sst mode. these ETC setups when you apply light throttle go WOT in 5th gear all the time. wanna see what I mean? drive down the road about 45-50. apply light-medium throttle (but not enough to downshift). Make a mental note of the sound and acceleration. now slow back down to 45-50 and switch into sst mode (5th gear). apply the same amount of throttle...very little if any acceleration will occur. now slowly FLOOR it. Note the acceleration and sound at the floor matches what you got with light throttle is D5.
 
I called around until I found a service advisor that didn't just tell me "bring it in and we'll look at it." He told me that he was familiar with the complaint and there are other TBW profiles they could load into the ECM based on a customer's preference (I hope this is true!). He also knew that the tranny only learns to tune the upshifts. Kickdowns are not "learned."

I have a feeling that the 3-2 kickdown reluctance is possibly due to being overoptimized for the artificial emissions and mileage test cycles. Since the manufacturer can't legally do anything that will change the emissions profile without recertifying, if anything, perhaps the EPA mileage might change a little (but that doesn't mean real world mileage would be equally affected).
 
Finally took it in for its first (5,000 mile) service. Told the power train guy about the crappy part-throttle kickdowns. He ended up applying TSB 03-15-08 (listed for the 2003 model year, although I have an '06) and the part-throttle kickdowns and overall operations are much improved. Part-throttle automatic upshifts occur higher in the RPM range and are smoother. SST downshifts are also smoother. Got hard into the rev limiter after kickdown by flooring it at around 60 once (traction control light also flashed briefly), but perhaps it's a "learning" issue (battery was disconnected as part of the procedure).

Very pleased with the overall results!
 
You must log in or register to reply here.

Members online

No members online now.
Total: 132 (members: 1, guests: 131)
Back
Top