Automatic not shifting correctly

[mikejpss]

Just realized that my 81 automatic is not going into first gear, or at least it seems that way, when I come to a stop. Sounds and feels like it starts out in second gear and only shifts once when getting up to speed. Unless first gear is ever so short in duration and shifting into second is so smooth that I can not hear/feel it, it's starting in second from a dead stop.

Please note that I recently changed out the carb to a non-computerized one, and changed the distributor to a vacuum advance model then I unplugged the ECM . This was all done in an effort to upgrade the motor performance (new motor installed too) and was recommended by a mechanic.
Did the changeover to a non computer carb/dist. do this to my transmission?
What could possibly be the problem if it did/did not?
I am transmission stupid other than changing the fluid/filter. Your help would be appreciated. Mike J.
:confused

 

[vettenick]

Check your throttle pressure cable. It's the other cable that's attached to the carb other than the gas pedal cable. It may be too tight.
Since you put a new carb, the cable is probably out of position.
This will affect trans shifting.

 

[vettenick]

Please forgive me! The cable must be too loose or not hooked up at all. It could also be broken inside of the housing

Good luck!

 

[mikejpss]

vettenick, Thanks for your info. I thought this cable was for when you punch down on the gas it would kick the tranny back down to second for passing gear. However, as I stated earlier I am transmission stupid and will check what you advised. Thanks for taking the time for the input. Happy New Year to you. Mike J.

 

[GerryLP]

Mike,

Here is some info to help you along. I think that should check the preliminary checks on page 7A-1. Also look at the modulator line for leaks at the rubber connections on both ends (at tranny and at manifold).

 

[GerryLP]

the trouble diagnosis chart (7 each)...

Also, the modulator diagnosis will be posting numer 9...

 

[GerryLP]

page 7A3-3

 

[GerryLP]

page 7A3-4

 

[GerryLP]

page 7A3-5

 

[GerryLP]

page 7A3-6

 

[GerryLP]

page 7A3-7

 

[GerryLP]

page 7A3-8. Final page of diagnostic table.

 

[GerryLP]

Mike,

This is the page for checking the modulator. Remember, its probably something short of overhauling the tranny...I mean simple...:L...Good luck and Happy New Beer ...I mean Year...

 

[mikejpss]

GerryLP- Thanks.
Where can I buy the shop manual that you posted pages of ?
I bought one that shows practically nothing and was a waste of money. Looks like your manual is the one to have-please advise where to get one- and thanks again for taking the time to help me.
Happy New Year , Mike J.

 

[vettenick]

Mike, goto Helm manuals on line. They do a lot of the OEM manuals.

 

[GerryLP]

Check Ebay L81 Shop Manual

Also try Amazon.com...

 

[mikejpss]

ok folks, I bought a shop manual and have read extensively on the transmission section. I would like to go back to my original question (on this thread) and re-ask it. :
Does the ECM have anything to do with the shift points, or does the ECM only monitor those shift points. Could the ECM be the cause (along with the others listed in the shop manual) for the trannny to NOT start out in first gear? Before I start to remove parts in a troubleshooting effort, would like to know more about how the ECM controls the tranny, if it does at all.
Thanks for all of your help thus far.
By the way, I should have bought this manual BEFORE the restoration started!

 

[vettenick]

The only thing the ECM controls is the torque converter lock up feature that occurs in 2nd and 3rd gears. And that only happens when the ECM gets proper input such as coolant temperature being at the proper temperature, oxygen sensor reporting in, which all leads to closed loop operation. That's where the computer is in control of fuel delivery....at least through the primary jets. Also, any sudden changes in throttle position sensor input could also affect lock up operation.

 

[mikejpss]

so, how will the tranny be affected if there is NO ecm on board?
When I changed out the original motor and installed a new GM crate motor, I went with a vacuum advance distributor and a 1980 model q-jet carb and left the ECM harness unplugged at the distributor. I was told by my mechanic that the only problem would be the "check engine" light would stay on, which it does.
Could someone please explain in simple english what this has done to the normal operation of my tranny and what I need to do , if anything, to upgrade/repair it to make it normal again.
Here are the symptoms:
Does not start out in first gear. Only shifts from 2-3 (downshifts ok)
Seems to burn a lot of gas- estimated at ~ 10 mpg
65 mph = ~ 3000 - 3200 rpm's
:cry

 

[vettenick]

Second gear starts sounds like a problem with the intermediate clutch.
This could be something as simple as low oil level/blocked strainer to something as complicated as a damaged clutch.
You really need to have the tranny tested with a pressure gauge.
On your car at this point, the ECM in or out, is not the cause.