1988 Corvette Trans. Problem

[Daryllawman]

I have a problem with my 88 vette auto tranny.........When the engine is cold, it will not go into over drive to take off. You have to put it in d1 and back to over drive several times before you can take off in Circle D....overdrive....after the car has been warmed up and driving, it goes right in overdrive and you want have this happen again until the next morning when you start it up again.......The trans doesnot slip and the engine and ride are great.....Can anyone tell me what this is? I have drained and refilled the auto tranny fluid and filter, with no change......;help ;help

 

[Eagle85C4]

Your throttle valve is sticking...common problem. I had the same thing and put a quart of Lucas Brand Tranny Additive and the problem went away. There also is a teflon coated throttle valve that can replace the stock one...

 

[Daryllawman]

:J Thanks Eagle.......I will try it.......

 

[vigman]

Ah... wait!

In MY 88..

There is a thermal sensor that opens the O/D electrical circut...

The sensor waits until a certain temp THEN allows the ECM to allow the O/D shift.

Now the IDEA is that when the fluid is COLD you have a greater chance of slippage if you romp on it.

It's in the shop manual.. but only for certian 700-R-4 models.

You need to find the tranny # on the side of the case before I can be 100% sure.

I'll bet if you now watch it it will shift whenever the water temp is a certian temp ( which will be a approximation of internal tranny temp )


Vig~

 

[BlackNBlue95]

Here is my suggestion.. let the car sit overnight so it's cold then in the morning let it warm up until the water temp is at norm operating temp and let us know what happens in OD then.. BTW in my SIG pic the top right corner I'm holding the burnt clutches from my trans LoL.. don't let that be you.. probably won't... but anyhow.. let us know what happens then.. I didn't look what state your in so how cold is it out when your having this problem?
-Rick

 

[Daryllawman]

Re: Ah... wait!

In MY 88..

There is a thermal sensor that opens the O/D electrical circut...

The sensor waits until a certain temp THEN allows the ECM to allow the O/D shift.

Now the IDEA is that when the fluid is COLD you have a greater chance of slippage if you romp on it.

It's in the shop manual.. but only for certian 700-R-4 models.

You need to find the tranny # on the side of the case before I can be 100% sure.

I'll bet if you now watch it it will shift whenever the water temp is a certian temp ( which will be a approximation of internal tranny temp )
Yes it does work when the engine temp gets to a cert. temp. Then it will work the rest of the day. It only does it when it is cold, engine wise not the temp outside......it could be cold or hot.....if the engine is cold it will not work. It will go into all the other gears fine, just not the overdrive......I can shift from 1st to overdrive several times and sometimes it goes in that way......So there is a sensor that tells it not to go in gear until it reaches a certian temp?

Vig~

 

[Daryllawman]

Here is my suggestion.. let the car sit overnight so it's cold then in the morning let it warm up until the water temp is at norm operating temp and let us know what happens in OD then.. BTW in my SIG pic the top right corner I'm holding the burnt clutches from my trans LoL.. don't let that be you.. probably won't... but anyhow.. let us know what happens then.. I didn't look what state your in so how cold is it out when your having this problem?
-Rick

If the engine is cold it willnot go into overdrive. After the engine warms up, it will go into it the rest of the day. Then in the morning the same thing.....its engine temp not the weather, it could be hot or cold outside.....same thing....not until the engine gets warm......sometimes when I shift from 1st to overdrive several times it might go into overdrive.....Vig said there was a sensor that tells it when the engine is warm.......

 

[vigman]

The sensor

Is in the tranny pan on the valve body... it's actually not engine temp.. but tranny fluid temp.... but since the tranny is cooled by the radiator.. the engine temp will be a GUIDELINE when the tranny sensor closes.


Vig~

 

[BlackNBlue95]

Re: The sensor

Is in the tranny pan on the valve body... it's actually not engine temp.. but tranny fluid temp.... but since the tranny is cooled by the radiator.. the engine temp will be a GUIDELINE when the tranny sensor closes.


Vig~

I agree with Vig then if it has a temp sensor in the trans like that then most likely this seems to be normal operation but has it just started doing this or has this been this way since you bought the vette..

On a side note isn't it kinda od I suppose the "Trans Cooler" in the radiator is a cooler because trans temp is usually higher then 190degrees.. but it also help warm the trans up because coolant temp I would assume would start to warm up faster then the trans if your sitting idle letting it warm up.. kinda works both ways is what I am saying it helps get the trans warm and helps keep is cooler once it's hot..
-Rick

 

[Daryllawman]

Black and Blue, its been like this ever since I have had the Vette. Once the engine gets warm, it works great....:confused :confused

 

[vigman]

So to prove the issue

We need the number off the side of the tranny.

or


You observation will suffice.....


Either way... I believe this is normal.


Vig~