: Touring: Trans in Auto vs Sport Mode ?



robhersch
09-26-06, 11:35 AM
Has anyone established any reasons for or against leaving transmission in "Auto" vs shifting to "Sport" mode - upshifting to 5 - while driving on a long trip?
I experimented with the idea on my '05 N* V8 RWD after reading about a "coaster brake action" drag (vs just engine braking) on the 5 speed trans.
My test was only one time ~ 250 mile road trip (LA to Las Vegas) using the speed control set for the speed of the traffic flow. My test seemed to indicate: 1) less up/ down shifting on long up-slopes, 2) less "drag" on long down-slopes, 3) ~10% better fuel economy than on previous trips over same roads (but on different days).
What penalties - excessive eng / trans wear, warranty, etc - might be expected from this? Thanks for all responses.

donjumpsuit
09-26-06, 12:58 PM
ok,
Here is a problem that I encountered with the tiptronic transmission. By no means should it be considered FACT.
I recently started using the tiptronic transmission exclusively. I was buggard by the fact that my V8 AWD 2005 seemed sluggish in 5th gear all the time. I liked to be in third or fourth for just the peepyness. I have never been shy about telling everyone that all my starts are jackrabbit starts and I am definately hammering my SRX, because its a lease, and I want to see what it can take, but after a month of mostly tiptronic, my SRX developed a problem.

The first time I took it in for service it had EIGHT engine codes stored in it. On a bunch of seperate occasions, mostly while using the tiptronic, I lost power in the engine, followed by the engine light coming on. The pedal feels soft, having power with a light touch, and having to completely pin it to the floor to get anywhere. In between there is no power on the pedal, like it is laboring, like an older car would do when it is "over heating" or on a hot day. They cleared the engine codes and sent me out to build them up again.

I returned the car recently with two engine codes stored. Needless to say the mechanics are in direct contact with GM because they have absolutely no idea what the problem is. They put the "black box" on the car and have been driving it themselves for a week (glad to see my 800 dollar a month lease payment put to good work).

I do not know the status on my car. It is in the shop getting the nav replaced that was stolen (previous post) but no word on what they are doing with the engine. I am crossing my fingers that they never figure it out and I can give my $24K car back to them that was $62k when I began the lease.

I relate this problem DIRECTLY to tiptronic transmission usage. I personally think (with modestly comprehensive mechanic skills) that the tiptronic signal has somehow screwed with the automatic transmission brain/engine computer and froze the cpu, or something to this effect. For instance when you use tiptronic, and forget its in 4th, and try to accelerate modestly at about 25mph, you have no power, essentially flooding the engine in too high of a gear. I think the engine somehow is getting messed up screwing with fuel/air mixture at that RPM. When returing to automatic mode, somehow this mixture is still mixed up.

my 2 cents

I will let you know what they find.

c5 rv
09-26-06, 02:12 PM
I fail to see the utility of a tiptronic transmission in a 4500 lb. station wagon. An autotrans with a sport mode, like was originally in the CTS, is sufficient for the SRX. A tiptronic in a lighter, more tossable car like a CTS makes a lot more sense.

TSS
09-26-06, 03:11 PM
I think tip-tronic is useless. In fact, I believe the car shifts better than me and I actually slow down my acceleration times trying to shift w/ the tip-tronic. I don't use generic sport mode either. BUT, if gas mileage somehow improves, I would. The original post had a disclaimer (about findings being fact), but I will try it (sport mode) too and report back.

medmarkco
09-26-06, 04:24 PM
I'm just the opposite - use tip exclusively. Mine's a V6 so I'm not so concerned about acceleration, but I must admit it would be a little too sluggish without downshifting to 3rd in some situations.

Primarily I use it for engine braking - I'm not a friction brake fan unless I have to. It may be psychological, but I think downshift kicked in stronger in the past than it does now (30k) - too much lag 4-3-2. I avoid really stressing it with 1st until doing 20mph or less. One of the reasons I chose an SRX over a Cayenne/Touareg was because the German tips didn't give me the tranny control the SRX does.

Maybe the SRX "tip change" is all in my head. Guess I'll go in for code checks. I have noticed a few acceleration situations on occasion where I didn't get the feedback I expected. A wrist flick or two and all is cool again.

dbknight
09-26-06, 09:14 PM
I hardly use the tip-tonic out of laziness I guess . . .

I do like using the Sport Mode though on the twisties, it holds a lower gear through turns . . . I will use it on my next trip and see if the MPG goes up.

keeton
09-26-06, 09:56 PM
V6 RWD here. I have not seen any real difference in normal driving the few times I have tried Sport mode.

I only use the manual mode ("tiptronic", "auto-stick" or what have you) when I am in slow, heavy traffic in order to keep the transmission in one gear so it won't be constantly shifting and (hopefully) saving wear on the gearbox.

I have found the manual mode fairly useless for sporty driving as there is a noticeable lag from when you select a gear to when it actually shifts. My other car is a Miata so I can enjoy real shifting (and really good shifting) when I want to.

robhersch
09-26-06, 11:28 PM
Thanks for the feedback to date. I regularly compare my N*V8 SRX (Jan 2005) with my wife's 1999 DeVille Concours (Dec 1998). So far I love both.
FYI - I acquired a "ScanGuage" ver 2.5 (ScanGaugeII - Scan Tool + Digital Gauges + Trip Computers (http://www.scanguage.com)) in mid 2005 after finding that my older ODB II "Code Reader" could not read the "CAN" trouble codes in the SRX. It works on both ODB II and CAN.
I have not (yet) had a warning light ON or any trouble codes reported on either car.
I like the tool - and for ~ $150 - seemed like cheap visiblity vs a $65-$100 charge by a repair shop or dealer to check for a code.
This tool not only lets me continously keep an eye on trouble codes regularly (& reset codes if needed) but it also allows reading of: engine load, gal/hr, ign timing, manifold absolute pressure, throttle position, coolent temp, batt volts, mi/gal from the SRX computer.

ckrichards
09-27-06, 09:01 AM
I haven't noticed any mileage changes, but I use it mostly for downshifts, also to help with the braking.
I also use it in the 45-50MPH range, since the tranny keeps going from fourth to fifth and back again. I usually will help it make up it's mind and pick one.
I also agree for upshifts the delay makes it nearly useless. If I want to hold gears longer on upshifts sport mode is much better.

DenverJag
01-28-07, 12:49 AM
When driving in high elevations and through the mountains, the "tip tronic" mode is very very helpful. Additionally, if you enjoy the ability to accelerate while traveling 45+mph, limiting the trans to 3rd, 4th, or 5th gear will also show its usefulness.

dcarr66
01-28-07, 03:24 PM
I have found the manual mode fairly useless for sporty driving as there is a noticeable lag from when you select a gear to when it actually shifts.

I've noticed this on my V6 AWD also. My last car was a '99 Intrepid with Auto-Stick, and it shifted much more quickly in that mode. IMHO, the sluggish response from the SRX really limits the usefulness of Sport Shift.

Does anyone know if this is mechanical, or something that could be improved by flashing the TCM?

louisn
01-28-07, 04:25 PM
I use the tiptronic only when merging on the freeway. 3rd gear and let her rip and watch the traffic disappear in my rear view mirror. After that I just put her in auto and enjoy the flexibility of the Northstar. :D

jigou
01-29-07, 05:42 PM
I'll pick a gear if I'm in traffic and want to just idle along, but when it comes time to stop I'd rather put the wear on my brake pads and rotors than the transmission.

I do have a tendency to bump the shifter over into the sport mode, but with a Miata in the garage (a racecar at that) I have to agree that the tiptronic shifter leaves a bit to be desired on the quickness of the shift....