new 86 vette owner:please help
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From: Bowling Green Ky
new 86 vette owner:please help
hey folks,just want to say in advance thanks for all the help...I'm the proud owner of an 86 for about 5 months now but can't figure out what I think is a transmission problem..auto 700r4 all stock car..trans shop says its an engine problem,mechanic shop says its trans problem..ok,at about 35mph is when it starts jumping back and forth,best way to explain it is imagine a manual trans in 5th gear running 20mph with clutch not pushed in and trying to coast,but when you give it gas and put it under a load it does fine..this is what my car seems to do..I replaced tcc solenoid,had valve body checked,and apparently had a 1-2 shift accumulator broke(?)anyways,both shops checked it off as good,yet still the problem remains...anyone heard of this,any ideas? thanks again
Race Director
Joined: Feb 2004
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The only thing the computer contributes to the 700r4 is a lock up signal. It is usualy a speed of about 35 mph that is programmed into the prom. What you are experiencing is normal, and annoying.
However, that is the way GM built them back in the day.
Your options are:
1) Live with it
2) Reprogram the prom to raise the mph (lock up apply) higher.
3) Rewire the lock up (in the pan) to work for 4th gear only.
Hurst makes a plug and play ( or at least they used to) adapter does the 4th gear only thing without cutting and splicing.
However, that is the way GM built them back in the day.
Your options are:
1) Live with it
2) Reprogram the prom to raise the mph (lock up apply) higher.
3) Rewire the lock up (in the pan) to work for 4th gear only.
Hurst makes a plug and play ( or at least they used to) adapter does the 4th gear only thing without cutting and splicing.
Racer
Joined: Aug 2006
Posts: 374
Likes: 4
From: Nevada Missouri
I had the same problem with my 86 and I replaced the the chip with a Hypertech power chip from Eckler's. Street Runner part # A9015 (cast iron heads) $234.99. Now it shifts like it should and very smooth. 
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From: Bowling Green Ky
thanks everybody,I'm relieved at least that it's not something serious but it is like you say very annoying..Thomas,does the chip you bought only work at full throttle or is this another one,I've had trouble trying to figure out what chip to buy if any..oh,I have a late 86 aluminum heads if that makes much difference..thanks again for the help
Team Owner
Joined: Sep 2003
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What I didn't hear is what gear are you in?
Can you feel/hear/see all four gears?
Can you detect when the TC locks up?
What gear is the trans in when the bucking happens?
The trans should shift into 4th and the TC lock at around 43-45MPH under steady throttle.
It sounds like the TC is locked, but you need to confirm the up shifting is normal and the TC locks.
Can you feel/hear/see all four gears?
Can you detect when the TC locks up?
What gear is the trans in when the bucking happens?
The trans should shift into 4th and the TC lock at around 43-45MPH under steady throttle.
It sounds like the TC is locked, but you need to confirm the up shifting is normal and the TC locks.
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From: Bowling Green Ky
JrRifleCoach,it does seem to shift through the gears fast,but I was told that was normal(?)..the bucking starts in 4th gear around 35mph and lockup seems to start around 40-43mph..I can drop it down in D and it is not near as bad but still detectable
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From: Bowling Green Ky
so I'm back to this annoying situation..now this bucking seems to be happening at faster speeds,say up to 50-55..it almost feels as though it only does it when you are barely on the gas,so I'm wondering is it possible that my tps may have a dead spot and getting worse?
this may not be something that could even be possible but I thought I'd ask...thanks
this may not be something that could even be possible but I thought I'd ask...thanks
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Burning Brakes
Joined: Feb 2010
Posts: 1,013
Likes: 2
From: California City Ca
Rewire
How do you rewire the lock up so it only works in 4th gear.
The only thing the computer contributes to the 700r4 is a lock up signal. It is usualy a speed of about 35 mph that is programmed into the prom. What you are experiencing is normal, and annoying.
However, that is the way GM built them back in the day.
Your options are:
1) Live with it
2) Reprogram the prom to raise the mph (lock up apply) higher.
3) Rewire the lock up (in the pan) to work for 4th gear only.
Hurst makes a plug and play ( or at least they used to) adapter does the 4th gear only thing without cutting and splicing.
However, that is the way GM built them back in the day.
Your options are:
1) Live with it
2) Reprogram the prom to raise the mph (lock up apply) higher.
3) Rewire the lock up (in the pan) to work for 4th gear only.
Hurst makes a plug and play ( or at least they used to) adapter does the 4th gear only thing without cutting and splicing.
Burning Brakes
Joined: May 2004
Posts: 1,230
Likes: 27
From: Athens Ohio
so I'm back to this annoying situation..now this bucking seems to be happening at faster speeds,say up to 50-55..it almost feels as though it only does it when you are barely on the gas,so I'm wondering is it possible that my tps may have a dead spot and getting worse?
this may not be something that could even be possible but I thought I'd ask...thanks
this may not be something that could even be possible but I thought I'd ask...thanks
Le Mans Master
Joined: Sep 2006
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
This seems to be spark plug wires maybe. I would change them to a good set, and make sure the plug end of the wire is pushed onto the plug securely.
It could be a misfire. If the car hasn't had a tune up in a while, give that a try. Replace the cap, rotor, plugs, wires, air and fuel filters.
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From: Bowling Green Ky
I guess I should add that I put the fuel filter on last night along with an oil change,and after while sitting in a drive thru with a car behind me I noticed it's headlights illuminating quite a bit of smoke coming from my car..this made me nervous so I pulled off and checked it out..it seemed to be white smoke but smelled more like gas than oil,this is the first time it has done that except for the usual puff of smoke on start up..not sure if this has anything to do with the jerkyness(new word
)back to the point,I wonder if the tps could be bad or could that cause this symptom...also could bad ujoints cause enough movement to make a car buck when not under a load..
these are just some thoughts so any comments on these or new thoughts would be helpful for process of elimination
