I am new to this forum, so this may be simple to many, but It has me stumped. Car is new to me, so I am trying to correct a few issues, and this very hard shifting 1-2, especially when parked overnight needs to go.
I have removed and cleaned and adjusted the IAC plunger to 1".
I have cleaned the TBI, and adjusted the TPS to 0.62 volts.
I have tested and adjusted the TV cable by depressing the re adjustment tab and pulling the slider back till it stopped and release tab. Cable is tight, but not as tight as a guitar string.
Still, initial idle is around 900-1000, with in gear 750-800 on dash gauge, and still shifting very hard 1-2. It does improve some after after runs for 3-5 miles. Please help, and thanks to everyone,

 

This problem will be in the transmission.. Not the engine controls.

How many miles?

If the TV cable isn't broken (When they're built right, you snap that cable and a ball pops up to give you max pressure) and you are handy with the tools.. Then check your 1/2 accumulator spring. (Breakage is common) Then, you might have a look at separator plate for check ball damage. Replace as necessary. (If you end up having to do this and it's new to you, feel free to PM me.. Some of the aftermarket plates cause as many problems as they fix)

RESIST THE URGE to loosen the TV cable to mask this problem.. You'll just burn the unit up that way.

Good luck.

 

Thought TPS should be around .54 anyone know if it makes that big a difference? Not a tranny guy but good luck with the fix

 

Confab,
It has 52600 mi, and the TV cable is not broke, and it has been adjusted as described in my post. It is tight, but not string tight.
Did you mean 1to 2 accumulator spring?
What is a good separator plate?
Should I use a B&M shift improver kit instead?
Should I replace the TV cable anyway?
I am servicing the transmission this week, while I install Magnaflow "Y" pipe and cats.

 

No need to replace the TV cable if it's not broke.. 52K isn't a lot.. Kind of surprising to hear of a problem with mileage that low.

And no.. IMO, you shouldn't be using B&M anything unless it's a shifter.

There's a thing in there called an accumulator piston. It's plumbed into the clutch line and just sorta bounces on springs to cushion the clutch apply. Sometimes the springs break (especially in the older units) and cause a harsh shift. Sometimes the check ***** punch through the sep plate and feed the clutch directly from a .250 hole, instead of about a .080 orifice.. And THAT will cause a harsh shift. But not typically at 52K though.

This stuff is easy to get to and check.. But, you're liable to tear gaskets and stuff.. If you're not comfortable doing it (and eating the bill for a rebuild if you mess it up) you might want to talk to a transmission shop.

There's other things that can cause this, of course.. They can rule these out with a pressure test.

If you're not either familiar with transmissions, or completely handy with the tools and the books, you might want to go that route.

If you think you're up for it, get the ATSG's book on the 700/4L60 and it will explain and show you what you're getting ready to disassemble. There will be like, little ***** everywhere and springs and pistons and stuff. None of it is hard, but it's more than many people want to tackle, and it all has to be put back together correctly or you'll burn it up.

 

Yes you are right. It is 0.54 +-0.075=.62, which should be within specs.

 

Confab,
It has been a long time since I worked on an automatic transmission, and I have a best friend that owns a shop with over 40 yrs of experience. Personally, I thing auto trans suck, but I bought the car at a very good price for the all family to drive and have fun.
I will have the entire accumulator rebuilt, separator plate and check ***** checked, and line pressure checked.
I hope that this takes care of it, and I can move on having fun with it, while working on get more hp for my bass rig.

 

Good luck!

 

Personal rule:
Hope for the best, but pray for the worst.

 

I have a 1990 also. This is a speed density system and not a Maf system. TPS is fixed so to speak...not adjustable like Maf. My FSM states a range from .36 to .96 volts. I miss the Maf set up as it adjusts so much easier to mod changes unlike Speed Density which has more fixed settings.

Bill

 

unclebill
the TPS is very adjustable, and all you need is 3 jumpers and a digital volt meter. Pull out the plug and insert the jumpers between the plug and TPS. Turn your key to ON but don't start the car. Take your reading at the TOP and MIDDLE jumper, and to adjust loosen the screws and it can be moved up or down. Down gives me a lower reading.
Now, to test if it is good do a linear test by slowly opening and closing the throttle, and if it is good it should give you an smooth reading up and down.

 

Confab,
Took the vette to my frind Bob, and we went for an extensive test ride with him and me driving it. We both came up with the same conclusion that it must have a very stiff shift kit in it, but as to what, only God knows. So we are going to take it apart tomorrow, and go from there in trying to correct the wrongs, before the driveline get damaged,

 

I'm not sure why there is a discussion about tips settings. The op has a 90 vette which has a 700r4. This tranny is not computer controlled except for the torque converter lockup. Shift quality and rpm are determined by hydraulics and tv cable adjustment, not the ECM.

 

383 Vette is right about that, BTW.. I'm relatively new and didn't want to step on any toes, but the TPS setting has nothing whatsoever to do with any of this.

Glad you and your friend are on the trail.. If he thinks it's related to a shift kit, pay special attention to the 2nd feed orifice. A lot of guys will just drill them out to to bump up the apply rate. There's a finite limit to this. You go much over .075 or so and you can get into an area that can become dangerous on anything but a flat, dry surface.

If it's been drilled out, you can take a steel check ball and place it on the orifice hole with a good piece of steel behind the sep plate and strike it with a hammer, thereby "peening" the orifice hole back down some and putting it back in line.

 

Confab,
Yes, 383 is right about tps on controlling the shifts, but it is a major performance player for fuel delivery if not adjusted correctly or not giving a good linear reading when manual opened during testing.
That said, I took the car to an old friend of mine that owns Mico Transmission, and after taking for a good long test ride with me, he told me that the TV cable was NOT properly adjusted. He has done 1000's of these, and has the same 4L60 (700R4) in his '38 Hot Rod.
When we got back to the shop, he made me adjusted like I did before per Haynes manual, and than he moved the adjusting sheath an moved it toward the TB 3 clicks. Took a metal ruler, manual pulled the cable forward and measured from the TB attachment tab to the very end of the cable 3/8". Great improvement with 5000rpm at WOT shifts good and firm. We went back, and he set it to 7/16" still good and just a tad less firm. His rod is set at 3/8", but I decided to leave mine at 7/16", which gives me the option to pull it back to 3/8" if I want.
Now, we are working on the lash going from P to D, since the P to R is good.

 

I won't argue about it, but the TV cable shouldn't be used to tune the firmness of individual shifts.

From ALLDATA:
Best wishes!

 

 

Confab,
Life gives us enough grief that I diligently try not to argue. But, Mike did make very good valid points of wear and stretch over the years, and his own ride with the identical year trans. We will be dropping the pan on Wed, and since the accumulator is very accessible, I will pull it and CK on that spring. Also, we will be CK line pressure at Minimum TV (75-85psi)and Full TV (165-200psi) at 1000rpm and 2000rpm. I will be using Brad Penn III H ATF. Any thoughts on that? Thanks

 

Venom
I was talking about the entire shifting pattern, 1 to 2 12-15mph, 2-3 22-30mph, 3-4 42-46mph in normal driving. At WOT, rolling from about 5mph, she is very firm and 5000rpm shifts.

 

That's fine..
Yeah, actually I do.

I really am not as concerned about brand names, or even synthetics, as I am about changing the fluid.

Example: Mine is filled with standard dex/mercIII I buy in bulk and it's fine. It'll be fine as long as it's maintained.

And there's more than the accumulator.. A bunch of guys hog the feed orifices out in these as a matter of course. They install cheap shift kits and such to get a rock hard shift. So, if you don't find it there, you might get your friend to take a peek at the sep plate also. See if someone played games with a drill bit on it.

Happens a lot.

Also gives you a chance to flip the valves a little and look for debris and damage you can head off early. (like the check ball hammering issue)

Good luck!