1993 4L60 trans problems

1990BerettaGTZ2.3L · Post by **1990BerettaGTZ2.3L** » Thu Jul 19, 2012 8:34 pm

Ok it's not beretta, but it is my dd to make the mula so I need some help...let my first say this is a one year only car with it's computer operating system and it's transmission for the body style it is, this is the only year newer body style with the non electronic 4L60 so thus should be easy to figure out. For the past 6 months or so I've been driving my car about 75 miles to work and home everyday, and everyday, when my car is cold fir like the first 15-20 minutes my tranny is fine it stays locked in 4 gear, well when it warms up after awhile it gets touchy and if you let off the gas alittle bit it downshifts to 3 gear and stays unless you give it alittle more throttle but when you do that it goes over the speed limit you want then you got let off the throttle again does the same thing. Well when it's been running for longer than 30 minutes it does not lock in 4 gear at all unless you give it like 1/2 to 3/4 pedal to the floor and it trys to lock in then quits and goes to 3rd gear, if someone know what would cause this could you let me know it's burning a hole in my pocket for fuel mileage right now and it's driving me crazy.

Edit: this is my 93 firebird 3.4L if that helps guys
Ps the fluid is like new and at the right level

Koots · Post by **Koots** » Thu Jul 19, 2012 9:17 pm

Have you changed the fluid recently?

Are you throwing any codes or CEL's?

Have you tried cleaning your throttle body out with spray cleaner?

Have you tried properly adjusting your TV cable?

1990BerettaGTZ2.3L · Post by **1990BerettaGTZ2.3L** » Thu Jul 19, 2012 9:32 pm

Fluid isn't even 10,000 miles old I changed it right before spring, didn't throw any codes except for my CEL being on everytime I let off the gas after 50 mph, it says the right side is running lean, and on top of all that it has a he'll of a time getting through 3,000-4,000 rpms like it's not getting enough fuel but after that it's fine and goes to 5,000 rpms and shifts when I'm really in it of course, didn't clean TB should I? What's the TV cable?

Koots · Post by **Koots** » Fri Jul 20, 2012 8:11 am

I meant to say, when was the last time you changed the FILTER

You should just try and clean the TB anyway, regardless of whether it might fix your problem or not. The TPS sensor alone can cause a myriad of driving issues if it gets dirty. Other times it can be caked in dirt and run like nothing was wrong...but with these computer controlled engines, it's always a quick and safe bet to rule out a dirty TB as the cause of your problems by cleaning it.

The TV cable is the Throttle Valve cable, which is what modulates the rising line pressure....which in turn effects shift effect and quality. Over time they tend to stretch a little and get loose, which can show up as a gradual softness in shift feel...which can also just come with age. So it goes unnoticed...but improperly adjusted TV cables are the number one killers of the 700R4/4L60 transmissions (along with heat, as is the case with all AT's).

It should be on the throttle body, next to the throttle cable using the same mechanism.

There is a ballpark way of adjusting your TV cable, but I was never truly happy with the feel by doing it this way. I got it close to how it used to be, without shifting harshly or too soft. You need to hook up a pressure tester and check line rise to truly get the TV cable adjusted perfectly.

ifixalot · Post by **ifixalot** » Fri Jul 20, 2012 9:21 am

I would check to see if you are overfilled on transmission fluid. If too full and then as it expands, it'll reach moving parts and get whipped into a foam.
If this tranny has a vacuum modulator, I'd check the lines going to it and then the modulator it self to see if it holds vacuum.

One more thing to try if none of the above are bad. If this is a high mileage trans, try some of that seal rejuvenater stuff they sell at the auto parts stores. It softens the seals in the clutch packs and helps old stiff seals. Perhaps the old fluid had some of that in there and when you changed the fluid, it caused the seals to harden again. It'll cost about $10 and take 100 miles to work if it works at all for this problem.

Koots · Post by **Koots** » Fri Jul 20, 2012 10:36 am

jskiguy wrote:I would check to see if you are overfilled on transmission fluid. If too full and then as it expands, it'll reach moving parts and get whipped into a foam.
If this tranny has a vacuum modulator, I'd check the lines going to it and then the modulator it self to see if it holds vacuum.

One more thing to try if none of the above are bad. If this is a high mileage trans, try some of that seal rejuvenater stuff they sell at the auto parts stores. It softens the seals in the clutch packs and helps old stiff seals. Perhaps the old fluid had some of that in there and when you changed the fluid, it caused the seals to harden again. It'll cost about $10 and take 100 miles to work if it works at all for this problem.

I agree with this and ultimately might be a simpler solution than mine.

Most "fixes-in-a-bottle" are worthless for more than adding some lubricity to moving parts and swelling up, dried out old seals. So it's okay to use them for this purpose.

I used Lucas Trans Additive in my aging 700R4 and it handled a loooong road trip (half of which was a gravel "highway"). When I got home, I changed the fluid and filter and ran the transmission for another 6 months. This was with 35" tall tires and the stock 1983 transmission and nearly 200,000 original miles. I eventually killed it by adding more power and killing it within 3 hours

Beretta.net