Automatic not Downshifting WOT
Thread Starter
6th Gear
Joined: Dec 2010
Posts: 6
Likes: 0
Automatic not Downshifting WOT
Please help i have brought my vette to my fathers mechanic and he is an idiot. the guy had the car for 2 months and still cannot figure this out. When you try to go to WOT from complete stop or any gear it holds the rpms and does not shift. If you ease off the throttle to about 1/2 it will start to pick up speed again. This has been going on for awhile now but my father like most vette owners baby it too much and never noticed since he never pushes it. If anyone out there has had this problem or know about other people with a similiar problem let me know.
Thread Starter
6th Gear
Joined: Dec 2010
Posts: 6
Likes: 0
sorry i forgot that part. '89 vette automatic no mods all stock for the most part. And yes the overdrive works. if you ease into the throttle you can get it up in the 90s with no problem. you just can't get there as fast as you would like.
Instructor
Joined: Dec 2006
Posts: 137
Likes: 0
I had something similar happen to my 92 LT1 with 700R4 after getting in snow and spinning the rear wheels excessively one winter.
With the engine not running try 10 quick stabs to the floor on the accelerator pedal.
This should unstick the transmission Throttle Control Valve.
Give it a try! Won't cost a dime!
Worked on my car!!!...and 4 years later no transmission problems to date.
Last edited by 92WhiteVetteGuy; Dec 1, 2010 at 07:47 PM.
Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
please try to explain better it almost sounds like you are saying you floor it and you gain no power that you have to ease on the gas to get any where. If that is the case I would be looking away from trans and looing at a cluged fuel filter or clugged converter. but try to explain some more to give us a better idea and more info
Thread Starter
6th Gear
Joined: Dec 2010
Posts: 6
Likes: 0
Well it is not fuel the mechanic check all the injectors and the fuel flow, if you rev in neutral it will do just fine. exhaust sounds good just a little rough idle. he ruled out the computer by replacing it and since it did not fix it he put the original back. I think it is trans solenoid thing but i don't know how to prove that. The mechanic gave it back still broken or at least with that same problem. It runs fine as long as you dont go 1/2 to wot. if you do it holds the rpm to 3200rpms. you feel like it wants to go but just holds you have to let off the thottle to 1/2 and then ease to speed up.
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Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
if it is holding at 3200 somthing is holding it back and probley not the trans. I would take it else where. 89 are not that difficult to dianoise. did he test the cat and test it correctly? was he checking fuel preesure while driving? Again from what you are saying sounds to me like a cluged cat or fuel problem. Again any good teck should be able to fiqure this out esp sense it is acting up.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
rodj that is why I asked him to explain better. I sorta felt after reading and rereading his first post it did not seem like a trans problem sorta got a feeling the rpms were not building and the only way he can get it to p/u speed is to go at it easy,
Thread Starter
6th Gear
Joined: Dec 2010
Posts: 6
Likes: 0
My mechanic did the following: None of it made any changes.
1. He dropped the exhaust system several times to make sure no blockage.
2. Overhauled the distributor, new cap, new dust cover, new rotor, new coil and new wire connectors. (new parts stayed in car)
3. Drained gas from tank, blew gas line clean all the way to the fuel rail. New gas filter again. No gas contamination. Put new gas in tank.
4. Checked fuel pressure at idle and as high as he could with a solid 40 PSI pressure. (no fluctuation)
5. Replaced the computer twice with no change. Did not replace the E-PROM.
6. New plugs, new wires and coil wire.
7. Transmission fluid looks and smells new. He did not feel that was a problem.
8. Diagnostics showed no computer glitches or problems at idle or running down the road.
1. He dropped the exhaust system several times to make sure no blockage.
2. Overhauled the distributor, new cap, new dust cover, new rotor, new coil and new wire connectors. (new parts stayed in car)
3. Drained gas from tank, blew gas line clean all the way to the fuel rail. New gas filter again. No gas contamination. Put new gas in tank.
4. Checked fuel pressure at idle and as high as he could with a solid 40 PSI pressure. (no fluctuation)
5. Replaced the computer twice with no change. Did not replace the E-PROM.
6. New plugs, new wires and coil wire.
7. Transmission fluid looks and smells new. He did not feel that was a problem.
8. Diagnostics showed no computer glitches or problems at idle or running down the road.
Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
Still does not explain why you are not able to pull more then 3200 RPM's. honestly I cannot recall ever seeing your trans keeping an engine from reveing. Sure anything is possible, but just so strange. I would get someone to check the exhaust again and do it the correct way.
Thread Starter
6th Gear
Joined: Dec 2010
Posts: 6
Likes: 0
Well im sure the rpm is being held by the computer because the transmission is not shifting. There is no way to tell unless you are a corvette engineer. They may have put in a safety to keep the rpm from redline if the transmission is engaged but not engaged. my dumb *** mechanic thought the same thing fuel and computer for 2 months and nothing he did made any difference. like nothing changed from changing and testing.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Computer only controls the convertor lockup which is not your problem
As stated above , symptoms you show are consistent with a blocked cat or fuel del problem
http://forums.corvetteforum.com/c4-t...-any-gear.html
Last edited by rodj; Dec 7, 2010 at 07:00 PM.
Burning Brakes
Joined: Oct 2009
Posts: 773
Likes: 2
From: Minneapolis MN
Time to bring it to a transmission shop or maybe one of the trans. experts can offer advice even though they may have already.Sounds to me like a kick-down problem.Hope he adjusted kick-down cable properly.Either way,time to bring somewhere else
Instructor
Joined: Dec 2006
Posts: 137
Likes: 0
Hi,
I had something similar happen to my 92 LT1 with 700R4 after getting in snow and spinning the rear wheels excessively one winter.
With the engine not running try 10 quick stabs to the floor on the accelerator pedal.
This should unstick the transmission Throttle Control Valve.
Give it a try! Won't cost a dime!
Worked on my car!!!...and 4 years later no transmission problems to date.
I had something similar happen to my 92 LT1 with 700R4 after getting in snow and spinning the rear wheels excessively one winter.
With the engine not running try 10 quick stabs to the floor on the accelerator pedal.
This should unstick the transmission Throttle Control Valve.
Give it a try! Won't cost a dime!
Worked on my car!!!...and 4 years later no transmission problems to date.
Did you try this?
Le Mans Master
Joined: May 1999
Posts: 6,517
Likes: 1,304
From: Windermere FL
Pete the resident expert needs to chime in on this one.
I have the exact same problem. Mine was caused by replacing the blown Corvette tranny with a non-Vette tranny. There are internal part differences on the vette version of the GM tranny that do not go into non-vette trannys and this is on of the symptoms that is causes. I almost wish mine would blow again so I could have an excuse to replace it with the proper tranny.
Pete has told me in the past the only way to correct this is to R&R the tranny with a vette one or do a complete R&R and replace/rebuild with the listed parts with the proper vette only parts. He had a list of the part posted somewhere.
I have the exact same problem. Mine was caused by replacing the blown Corvette tranny with a non-Vette tranny. There are internal part differences on the vette version of the GM tranny that do not go into non-vette trannys and this is on of the symptoms that is causes. I almost wish mine would blow again so I could have an excuse to replace it with the proper tranny.
Pete has told me in the past the only way to correct this is to R&R the tranny with a vette one or do a complete R&R and replace/rebuild with the listed parts with the proper vette only parts. He had a list of the part posted somewhere.