Hello. Great site. I"m a new member and a new vette owner. I thought I got a good deal buying an old '88 with a blown headgasket for $4500,
I"m not a mechanic and haven't really worked on any car or done anything other than an oil change in 10 years. Long story short, I got the thing torn apart, replaced the headgasket and then put everything back together. I ran into minor problems, tired, worn out vacuum hoses that were brittle etc...extra parts that I eventually figured out where they went bla bla bla...I finally the get car fired up and reasonably timed and running ok after dealing with old gas in the tank problem and I still have some vacuum issues to deal with...took it for a drive...shifted from neutral into OD accelerate no problems...get to about 28mph in OD and the trans seemingly kicks into neutral.
Does this as well in D and 2nd I think, first gear I can get up over 40 no problems. Is there some kind of linkage that would effect the transmission this way? Does the computer control something that would cause this problem? Did I screw up something on the throttle body and not hook it up properly? The person I bought the car from is a friend of a friend and honest as far as I know and I'm pretty sure the guy would have told me there was a trans problem. I want to get anyone and everyone's opinion about this before I confront the guy and or pull my hair out. Your comments are appreciated. Also remember I know squat and did this all on my own with a chiltons. Spell out any abbreviations and explain it like i'm a complete moron. Thanks.

JR.

 

I'm not an auto tranny expert-but two things 1. check fluid level. 2. Do yourself a hugh favor-get the FSMs or Helms-they are the bible for us C4 owners. I bought both volumns of the FSM (factory service manuals) off ebay for less than $100. They've probably saved me 5 times that.
And welcome.

 

I think there is a mechanical malfunction. I had a 1983 S10 Blazer that did the same thing, I had broken parts and needed a new converter. I had a trans shop rebuild it and thats what they told me. Bad overdrive sprag and the converter ate chunks from the first problem.

Good luck to ya, Tom

 

I checked the trans fluid. It was at the correct level and the fluid looked good, not burned out or corroded like there was damage. C'mon guys where's my miracle solution? I can't afford 1k for a new trans and I really don't want to have to deal with that monster myself.

 

Did you mess with the TV cable? Knowing the adjustments for the tranny are something one cannot describe (at least I can't) on the internet. Once again the FSMs are full of sections and have great trouble shooting flow charts-less than taking it to a tranny shop, and the additional information will save you alot of headaches.
Both the Haynes and Chiltons are simply not adequate for year specific vettes, and really have no help as far as trouble shooting.

 

No transmission guy here either. But Pete K could probably give some good suggestions.

 

Are you saying here that you were fooling with the valve body of the transmission while you were changing a head gasket? The computer only locks and unlocks the TCC which has nothing to do with your problem. That Chiltons you used is OK for yeoman wrench turning, but if you ever get into anything Corvette specific, or trouble shooting, you will need the FSM (Factory Service Manual) as rick lambert pointed out. For clarification, the FSM is printed by Helm Inc. under contract with Chevrolet. On THIS forum, we use "FSM" and "Helms", interchangeably. Since Helm Inc. prints authorized service manuals for other companies, that interchange of terms isn't universally correct.

Your transmission problems sound like the trans is terminal. You can take it and let a trusted expert test drive it, but don't hope too hard for good news.

RACE ON!!!

 

Read -> http://www.tvmadeez.com/article/index.php

Adjust TV, and drive. Cross fingers in hopes this is the problem. I've seen a misadjusted TV Cable do some odd things but I have never seen one cause a tranny to act as you describe. Not that it may not be possible. I am apt to agree with CFI-EFI and think it may be time for a rebuild.

You might be able to save some coin (maybe $200-$400) if you can remove and reinstall the unit yourself.

 

I disconnected the throttle body when I took the top end apart. I never disconnected the cables themselves from the throttle body but merely moved it aside intact. I've called a few shops around the country and have gotten different answers. One guy told me I may have a vacuum issue since I"m not sure if I connected all the vacuum lines correctly and that the vacuum can effect the transmission's shifting. Under the plenum especially is a problem. There are vacuum diagrams in the chiltons but they're not specific enough regarding the vacuum connections under the plenum. I need pictures and in hindsight, I should have taken some digital pics of all the vacuum lines before I took it apart. If anyone with an '88 or the tuned port injection set up gets real bored and wants to send some pics of the hookups under the plenum I wouldn't mind.

Also I didn't know to check the trans fluid at idle so that's another thing to check. Another tech told me to check the vacuum modulator, the throttle position sensor and the kick down cable from the transmission. Any other suggestions I'm all ears.
thanks.
JR.

 

Because of the complexity of the auto trans, very little can be done without removal and disassembly. The tv system can be checked and adjusted. Filter and fluid can be changed and the governor can be removed and cleaned. Otherwise, you may be at the mercy of a repair shop.

 

Here's a suggestion, run away from those techs as fast you can


What Pete said

 

Alright, thanks for the advice. I'm hoping it has to do with the Throttle Valve cable. I talked tp one tech and he said the tv cable is supposed to be tight like a guitar string. I know for a fact it's hanging loosely and may very well be improperly set. If that's not it I"ll be buying a used transmission. Corvettesalvage in mississippi has one with about 70k for $450, $700 including shipping to california. If anyone knows of any good wrecking yards let me know and I"ll keep an eye open on the forum. Thanks again.
JR.

 

Not true. You are getting some severely flawed information, there. Nothing on the 700R4 transmission is influenced by vacuum.

As explained above...Not applicable to transmission operation.

All (that I know of) automatics are to have their fluid check with the engine idling. Some in Park/Neutral, others in drive. The 700R4 has no vacuum modulator. The TPS adjustment has nothing to do with 700R4 operation, and finally, the 700R4 has no kick down cable.

The TV cable takes a single, non-skilled, adjustment to get it right 95% of the time. Once you adjust it per your FSM it will be as good or better than when you bought the car. While you are waiting for your FSM, you will find the TV cable adjustment in the search function, or maybe someone has saved a link to instructions. This forum's best auto trans man is Pete K. You can take his trans info to the bank. You are getting so really bad info somewhere.

RACE ON!!!

 

of all the advice u have gotten pete k gave u the best
listen to him
now theoretically you can rebuild the tranny your self for the prices of a kit. summit racing sells tci kit for $220, they also sell a b&m kit for a little less and the b&m kit is supposed to be idiot friendly.
this assumes u have the tools (i have found a site that will tell u how to make the speciatly tools you need)
there are 3 sources of info u should get one is a dvd video that will take you right through the rebuild (its a good video) (i think its $25) do a look up of technical video on the net
next is the atsg (automatic transmission service group) manual (aprox $15) the other book is a haynes manual on gm auto transimissions (i found this not as usefull as the other 2 but if u get in to a bind it might get u out and its cost is $!5)

this is no bigger project then changeing the head gasket on a c4
and a really good learning experice
if u go this route u will have a good trany
a used trany who knows what your getting in to

pete k might beable to add to what i said

 

I agree. If you feel confident, there is no reason you cannot do the rebuild, if you choose to do so. Most people would rather not because they are intimidated. Rightfully so, they are tough, but doable. If a dope like me can do it, anyone can I can also direct you toward parts and pieces that high quality and not expensive.

 

I have an 88 also and have noticed what seemed like sllipping between 1st 1nd 2nd. Suddenly the other day I couln't get out of first. Checked the governor which was fine. ( Had a tranny guy look at it too)Changed tranny fluid and still have the same problem. I keep hearing about the Tv and dont know where or what this is. Can the tv adjustment suddenly go out?
If I need a rebuild I would like to attempt to it myself. Can anyone give more advice concerning this? Is there specific information available.

Thank you!!

 

The TV cable doesn't suddenly "jump" out of adjustment. The adjustment could slowly deteriorate over the years, as the cable stretches with use. It wouldn't hurt to check or readjust your cable to reassure yourself, but it isn't likely to be the problem. It sounds like it is trans time for you too.

You need more references than jeffyc provided? For both the TV adjustment AND the overhaul, the FSM is a great source of info.

RACE ON!!!

 

Like any other valve in the valve body, it can also stick. They rarely do, but could. The cable adjustment is simply a way to keep the valve located so that it "strokes" properly during varying throttle positions.
Fwiw, your problem , if not the governor, sounds like the band apply is weak.