Driving ?s--what's normal?

[peeeot]

I've had my 91 Cutlass Supreme conv. 3.1 long enough now to notice some things about how it drives that seem peculiar. I'm wondering if my experience parallels everyone else's.

 

One thing is the 4t60 transaxle's unwillingness to leave OD once it's there, and flat refusal to downshift from OD to 4th (it always skips to 3rd when it does it). If I come to a hill in OD at around 50 mph and don't have enough momentum, speed will drop and drop and I'll dig into the throttle what feels like more than enough to get a downshift but nothing happens. Dig far enough by the time I've reached like 37 mph and it slams down into 3rd and winds up high. Shouldn't it just downshift to 4th?

 

The other thing I'm wondering about is how lazily the car accelerates if it isn't kept close to 3k rpm. To date, I usually drive with minimal throttle, such that I may touch 3k in 1st but it mostly shifts around 2.5k. At that rate, I'm one of the slowest-moving cars in traffic. If I give enough gas to keep up with traffic, especially up hills, the engine spends most of its time close to 3k rpm as I accelerate. I feel like it's got to be drinking gas, winding up like that, and I'm not even driving fast! Is that normal behavior?

[89GP_SE]

my question is ... isnt OD 4th gear, and when it shifts down it goes into 3rd. Second of all my grand prix hesitates sometimes to downshift. But I can also go up a hill at 60mph with the cruise on and it still doesnt downshift.. just stays put. My old gp would have downshifted. Every car is different.

[Stevo]

OD removes the engine's braking ability to slow the car down when your at high speed, say on the hiway.

[ns87]

My car finally drops out of OD at 40mph. It doesn't do it nicely either! Our transmissions are so freakin weird. Try going uphill around a sharp turn at 20mph. Odds are your transmission will fall out of gear and catch again.

[Supreme Cutlass]

My car finally drops out of OD at 40mph. It doesn't do it nicely either! Our transmissions are so freakin weird. Try going uphill around a sharp turn at 20mph. Odds are your transmission will fall out of gear and catch again.

you, sir, should check your tranny fluid

[91GPSTE]

Your trannies are messed up. When I am crusing down the highway in OD with cruise control set, the car won't accelerate by itself or decelerate when going downhill for that matter. It will do it slightly, but it won't replace the brake and gas pedals. It clearly states that in the manual. You have to push the gas/brake pedal to do it. When going up hill, I have to push the pedal down quite a bit to get it to shift into 3rd. All trannies are like that as far as I know. It won't be instant touch the gas and it shifts unless you floor it.

 

As far as acceleration goes, mine accelerates nicely.

[peeeot]

my question is ... isnt OD 4th gear, and when it shifts down it goes into 3rd. Second of all my grand prix hesitates sometimes to downshift. But I can also go up a hill at 60mph with the cruise on and it still doesnt downshift.. just stays put. My old gp would have downshifted. Every car is different.

 

no, OD isn't 4th gear. My transaxle consistently shifts 4 times, making for a total of 5 forward gears. The 5th is OD. I'm not sure how it's set up on FWD cars, but on RWD cars (at least in the past), OD is like a separate little 2-speed transmission hooked up to the back of the normal one. Top gear would always be 1:1, and OD would be something like 0.85:1. For reasons that escape my understanding, 2nd and 3rd gear on the 4t60 are really close together, then 4th is a big jump from 3rd, and OD is still another big jump.

 

I'm not positive about this, but I think that OD used to be operated electronically while the normal transmission shifted by hydraulic pressure. If this is still the case on the 4t60, then it might explain why it's reluctant to leave OD--it's not regulated by hydraulics like the rest of the tranny and communication between the tranny and OD aren't as good as within either unit.

 

Am I way off, close, what?

[Psych0matt]

i have thought before that I felt 4 distinct shifts, and i was actually wondering earlier about this

[89GP_SE]

i only feel 4 shifts

[93z34]

5 forward gears? I didn't know we had 5-speed transmissions. OH.... wait... we dont

[Regal_GS_1989]

There is 4 forward speeds and yes, OD is 4th gear, then there is also lockup. When the Torque convertor locks up, it will feel as if the car is shifting into a 5th gear.

[Supreme Cutlass]

There is 4 forward speeds and yes, OD is 4th gear, then there is also lockup. When the Torque convertor locks up, it will feel as if the car is shifting into a 5th gear.

x2

[peeeot]

There is 4 forward speeds and yes, OD is 4th gear, then there is also lockup. When the Torque convertor locks up, it will feel as if the car is shifting into a 5th gear.

 

I think I may know what's going on now.

 

Look at these links: http://en.wikipedia.org/wiki/Overdrive_%28mechanics%29

http://auto.howstuffworks.com/automatic-transmission8.htm

 

So after looking at those pages, the system I'm referring to seems to appear only on RWD cars. There is no separate overdrive unit for FWDs. Now that you mention the lockup converter, and the fact that it results in a small drop of rpms, I realize that what I have thought to be a 2-3 shift (which seemed almost pointless, the gears were so close) must actually be the lock-up converter engaging. That would make what I thought to be a shift into OD as a 5th gear actually a shift into OD as a 4th.

 

Yes? No?

[Nick1234]

Ok the tranny is 4 gears. Lets say you are getting onto a freeway and you have the tranny in D. 1-2 2-3 3-4, THEN, the torque converter locks up. What you are explaining is exactly what my car does. I noticed it did this after i opened my exhaust. Now when you hit the brake say when you are doing 60 mph, you torgue converter unlocks due to the brake switch. then you are in forth. For my car, i have to go about half way doen before the converter unlcoks, then it goes into 3rd.

 

As for acceleration, again i would agree, Around 3200 rpm, i feel more power but that falls off right again. Thats at about 1/2 throttle. As of lately my car is sucking gas, and i know EXACTLY what you mean about it feeling like its sucking gas.

 

 

Nick

[94CutlassXtreme]

OD is forth gear and it has a gear ratio less than third which is 1:1. All it does is put the engine at a lower RPM to maintain speed and improve fuel economy.

[1990lumina]

You will want to push it to 3200rpm anyway because that's where the 3.1 makes the most torque.....and I believe max horsepower is around 4k??

 

As for cruise mine holds the speed okay, but it's not great. Though when going up a hill it will downshift right away, but it does this stupidly. It'll downshift, speed up, then shift into OD again, then slow down, shift, speed up, etc....so I take over and manual shift it into Drive with cruise still on, no problems.

 

As for engine braking, I doubt my car ever does it...when driving down a hill it'll increase speed by at least 10km depending on the grade.

 

I like my mom's Acura's cruise control....when going down a hill it'll immediately shift into a lower geara nd hold the engine rpm to maintain speed, and when going up a hill it shifts right away and holds....

 

My dad's Suburban is sorta wierd because it never shifts out of OD when cruise is on going up a hill....I guess it doesn't need to because it holds the spped perfectly

[89GP_SE]

You will want to push it to 3200rpm anyway because that's where the 3.1 makes the most torque.....and I believe max horsepower is around 4k??

 

As for cruise mine holds the speed okay, but it's not great. Though when going up a hill it will downshift right away, but it does this stupidly. It'll downshift, speed up, then shift into OD again, then slow down, shift, speed up, etc....so I take over and manual shift it into Drive with cruise still on, no problems.

 

As for engine braking, I doubt my car ever does it...when driving down a hill it'll increase speed by at least 10km depending on the grade.

 

I like my mom's Acura's cruise control....when going down a hill it'll immediately shift into a lower geara nd hold the engine rpm to maintain speed, and when going up a hill it shifts right away and holds....

 

My dad's Suburban is sorta wierd because it never shifts out of OD when cruise is on going up a hill....I guess it doesn't need to because it holds the spped perfectly

 

When going down a hill, my cruise keeps me at that same pace I had it set for, doesnt gain any speed just wont let it. Going up a hill, it has never shifted out of OD... no matter what grade of hill I take it up, it hasnt yet.

[1990lumina]

You will want to push it to 3200rpm anyway because that's where the 3.1 makes the most torque.....and I believe max horsepower is around 4k??

 

As for cruise mine holds the speed okay, but it's not great. Though when going up a hill it will downshift right away, but it does this stupidly. It'll downshift, speed up, then shift into OD again, then slow down, shift, speed up, etc....so I take over and manual shift it into Drive with cruise still on, no problems.

 

As for engine braking, I doubt my car ever does it...when driving down a hill it'll increase speed by at least 10km depending on the grade.

 

I like my mom's Acura's cruise control....when going down a hill it'll immediately shift into a lower geara nd hold the engine rpm to maintain speed, and when going up a hill it shifts right away and holds....

 

My dad's Suburban is sorta wierd because it never shifts out of OD when cruise is on going up a hill....I guess it doesn't need to because it holds the spped perfectly

 

When going down a hill, my cruise keeps me at that same pace I had it set for, doesnt gain any speed just wont let it. Going up a hill, it has never shifted out of OD... no matter what grade of hill I take it up, it hasnt yet.

 

Do you lose speed going up the incline?? Who knows your engine is probably running better then mine and you can torque out to keep the car going the correct speed....

 

All I know is if it can hold a constant speed on flat land (like 80% of Saskatchewan's highways) it's good enough for me....damn I miss cruise in my RX-7 lol....

[peeeot]

Ok the tranny is 4 gears. Lets say you are getting onto a freeway and you have the tranny in D. 1-2 2-3 3-4, THEN, the torque converter locks up. What you are explaining is exactly what my car does. I noticed it did this after i opened my exhaust. Now when you hit the brake say when you are doing 60 mph, you torgue converter unlocks due to the brake switch. then you are in forth. For my car, i have to go about half way doen before the converter unlcoks, then it goes into 3rd.

 

As for acceleration, again i would agree, Around 3200 rpm, i feel more power but that falls off right again. Thats at about 1/2 throttle. As of lately my car is sucking gas, and i know EXACTLY what you mean about it feeling like its sucking gas.

 

 

Nick

 

Wait, so are you guys sure that the lockup engages ONLY after the car has reached 4th gear? The reason why I'm asking is because Never Satisfied said the lockup engage would feel like a shift with a SLIGHT rpm change, and judging by what is happening mechanically when it locks up, that makes sense. As I accelerate, the point at which I experience what feels like a shift but with slight rpm drop (200-300 rpm) happens in 2nd gear at around 2600 rpm with moderate-minimal throttle. The last of the 4 "shifts" I feel in regular acceleration is a larger rpm drop, more like 700 rpm, and it only happens at speeds above 45 mph.

 

Wish I could comment on the cruise control discussion, but I haven't used CC yet... no highway trips.

[Crazy K]

Peeot!

try determining which shift is actually the torque converter locking up by just slightly riding the brake while accelerating normaly through all the normal upshifts.

 

so everyone knows, the converter locks up under set conditions according the the ecm/pcm, something to the effect of... 45mph or faster, brakes not applied, light to moderate throttle... IIRC

 

the brake switch is multifunctional, it does the brake lights but also breaks the circuit that feeds the lockup converter.

 

 

btw, if you have a non electronic transmission, you can also unplug the harness connector at the front of the tranny. (92 and earlier W's, except the 3.4)

[ns87]

you, sir, should check your tranny fluid

 

Good call. I dropped the pan last week, checked it the next day. It was level, but today I was about half a quart low. Thanks man! I'll keep an eye on it incase I'm leakin somewhere

[1990lumina]

If you are in a cold climate you'll know which "shift" is the converter locking....When my car isn't warmed up enough and I'm on the freeway the converter won't lock until everything is warm enough...so at 60mph I'm probably cranking out 2500rpm....when it locks it drops to around ~1900rpm

[peeeot]

okay, yeah, I've noticed that my car doesn't do its last "shift" until I have like 3 or more bars of temperature on the gauge.

 

This poses a different question then. If the very last "shift" I feel is in fact the lockup engaging, then why are the 2nd and 3rd gear ratios so close together? I was watching my tach closely yesterday and the rpm drop between those two is definitely 300 or less rpm. The difference is so slight, I don't understand why the engineers would go through the trouble and expense to add the other gear.

 

Oh, and I got to use cruise control. When I hit hills, it didn't increase the throttle to keep up speed.

[89GP_SE]

i know its almost pointless to have that 2-3 shift there.

[mihela816]

The reason your convertible accelerates so slowly is because it is nearly 500 lbs heavier than other w-bodies. The 3.1 has to work hard to move that fat around.