how's it going, took the car for a spin today, and i noticed under light accelleration, from corners, stop signs or following slow cars.
my car is shifting into over drive at 50 km/h

i was wondering if this might be the tps or??

i'm really lost as to if its the transmission problem or what, i just went through with a dextron vi tranny fluid change 2 days ago.
but i have noticed low bogging after slowly accelerating to pass cars earlier than this, taking 50% or more to shift down. its beginning to concern me. PLEASE:helpsmilie:

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- Josh
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Your torque converter locks up in 3rd gear as well as OD.. are you sure that's not what you're feeling? After you feel it shift into "OD" does it shift again around 75-80kph? If so, that's probably what's going on.

sorry maybe my synopsis was a little brief, but no the last gear its shifting into is at 50 km/h, it just seems a little early to me, aswell as another problem is inclines, downshifting seems a little late taking alot to downshift, like a quick snap to the accelerator is needed before any action with shifting. is it my imagination that something seems different or lackin..?

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- Josh
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Normal.

In most situations you want the torque converter to lock up around 50 km/h (~29-30 mph, IIRC). Reduces wear on the transmission and improves fuel economy.

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2012 Chevrolet Cruze Eco - Current car

1999 Buick LeSabre Custom - Former car

Learn from the mistakes of others, that way when you mess up you can do so in new and interesting ways.

I don't think you should be hitting OD at 50km/h. That seems too slow of speed for OD.

I always thought that 4th gear lockup occurred at 45mph(72kph) with a fully warmed up engine.

Torque converter locking and OD are not the same thing. You should not be shifting into Overdrive (4th gear) at 29-30mph.
EDIT: Mark is right.. I believe it is set @ 47mph.

Wait, the RPM's dropping to ~1000 at 50 km/h is the torque converter locking in 3rd gear, not overdrive. True overdrive would bring the engine to idle RPM since from 3rd to 4th is a ~400 RPM drop. My ScanGauge shows RPM's at ~46 mph in 3rd as ~1750, then RPM's at ~48 mph in 4th as ~1300. 4th gear at 50 km/h means RPM's would be ~600-700, possibly lower if the converter locked.

I think it would be obviously lugging the engine if the RPM's were that low when in gear. At least my car lets me know through vibration and engine pitch that it's working hard at 1000 RPM at ~30 mph (~50 km/h) getting up a hill with the converter locked. It'll shift, but it takes a lot of gas pedal to make it shift.

To the OP: What are your RPM's at 50 km/h?

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2012 Chevrolet Cruze Eco - Current car

1999 Buick LeSabre Custom - Former car

Learn from the mistakes of others, that way when you mess up you can do so in new and interesting ways.

Shift points are variable. It will depend on gear selector position, vehicle speed, throttle position, engine load, vehicle weight (junk in the trunk) and transmission fluid temperature. Calculated engine load can be thrown off by a dirty MAF sensor.

If your not sure that the shift you felt was OD or the converter clutch locking, you can unlock the converter by tapping the brake pedal about a half inch but maintain the same throttle percentage. When the PCM sees a brake input, it anticipates a vehicle stop and unlocks the converter. It will lock the converter again when conditions are met and there is no brake input. When you do this, you should feel the converter lock and unlock and/or see the RPM's drop and rise with the brake input. If you do not notice a change, the conditions may not be met for converter lock, the converter may be malfunctioning or the converter controls may be malfunctioning. Lock up is only available in 3rd and OD. Lock up will not always activate in 3rd, lock up in 3rd usually only happens with light throttle and cruising speeds of 30-40 mph? Depending on your driving habbits, lock up in 3rd may almost never happen...or it may happen almost every time. Soooo many variables.

^^ Excellent post! That's what I was trying and failing to say.

_________________
2012 Chevrolet Cruze Eco - Current car

1999 Buick LeSabre Custom - Former car

Learn from the mistakes of others, that way when you mess up you can do so in new and interesting ways.

Agreed, but AFAIK shift points are not so variable that he should be shifting into 4th gear at 39mph.

I agree, but don't know what is causing it? I would take a look at the MAF sensor just because, but even if it is dirty I don't think it would cause this? Still easy enough to check though.

MAF sensor.. is it cleanable if it's dirty??
i'm gunna get a scan tomorrow im hoping from a guy around the corner.. maybe something will else will pop up!?

thanks again for all your help, i'm beggining to see why this site is such a success!
great people with a *shoot* wack of information.

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- Josh
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Search for "MAF sensor cleaning".

Heck, here's how: Get Q-tips and rubbing alcohol, and be very gentle. Or get MAF cleaner, and spray the living daylights out of it.

_________________
2012 Chevrolet Cruze Eco - Current car

1999 Buick LeSabre Custom - Former car

Learn from the mistakes of others, that way when you mess up you can do so in new and interesting ways.

thanks! will do once i get the chance roads are closed in my area today, so much for the scan.. :(

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- Josh
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I notice a huge difference in shifting between the 94 and the 00.

Lock up with the 94 occurs at much higher speeds (45 mph) than the 00 (30 mph). The 00 seems to lug much more but never locks below 1200 rpm.

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2000 SSEi - SilverBullet - 78,000 kms, 4" "straight shot" custom headlight ram air inlet, TOGs, 1.9's, Lsd, 2.9-3.4"MPS 10-15 psi, Ported GenV, EGR eliminated, OR pushrods, oil volume kit, trani cooler & shift kit, Titanium retainers, 90 lb springs, 160 Stat, 42# injectors, Fuel pump voltage increase, Wideband O2, 3" to dual 2 1/2" Magnaflows, Snow Meth/water injection, after SC temp gauge, 255/50WR17, timing commander set 15-18*@WOT, 2 speed Fan over-ride, disabled DRL, Solid motor mount, Meziere Electric water pump, adjustable fuel pressure regulator, Drilled & slotted rotors/ceramics, GXP sway bars and STB, Upgraded and rebuilt transmission with ZZP 2500 rpm stall TC, Pioneer Bluetooth stereo with sub and 800 W amps, PB 13.5 quarter, (April 2014 car of the month)

yeh i'm so used to my buddys 98 that mine when i started driving it a little easier lol, it seems weird?
glad to hear its nothin severe to be worrying about?

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- Josh
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The older Bonnevilles through 95 lock up at 36 in 3rd light throttle, and 46 in 4th light throttle.. The later years can lock up in 3rd at 28 Mph and OD at 44 Mph..

Good info.
So it's that 3rd gear lock-up at 28 mph that bugs me in the 00 !

I much prefer a little higher lock up in 3rd like the 94. In the 00 I'm constantly letting off the throttle to disengage the lock up so the rpm doesn't lug with all the hills around here. I know the reason for this is fuel economy but it just doesn't feel right.

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2000 SSEi - SilverBullet - 78,000 kms, 4" "straight shot" custom headlight ram air inlet, TOGs, 1.9's, Lsd, 2.9-3.4"MPS 10-15 psi, Ported GenV, EGR eliminated, OR pushrods, oil volume kit, trani cooler & shift kit, Titanium retainers, 90 lb springs, 160 Stat, 42# injectors, Fuel pump voltage increase, Wideband O2, 3" to dual 2 1/2" Magnaflows, Snow Meth/water injection, after SC temp gauge, 255/50WR17, timing commander set 15-18*@WOT, 2 speed Fan over-ride, disabled DRL, Solid motor mount, Meziere Electric water pump, adjustable fuel pressure regulator, Drilled & slotted rotors/ceramics, GXP sway bars and STB, Upgraded and rebuilt transmission with ZZP 2500 rpm stall TC, Pioneer Bluetooth stereo with sub and 800 W amps, PB 13.5 quarter, (April 2014 car of the month)

Even my L36 makes it up hills just fine in 3rd with the converter locked. It may not feel right, but it makes for excellent fuel economy and reduced wear on the transmission. I'll let off the throttle at about 30 to force the TCC to lock for the fuel economy.

_________________
2012 Chevrolet Cruze Eco - Current car

1999 Buick LeSabre Custom - Former car

Learn from the mistakes of others, that way when you mess up you can do so in new and interesting ways.