Still! c4 shifting problems - need to fix it in 36hrs!

C

C0V3R

Member

Feb 14, 2003

524

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16

Australia

Dec 12, 2006

#1

• Dec 12, 2006

• #1

So far I have been having no luck working out why my c4 wont shift at wide open throttle. It revs all the way out to 6700 rpm and still will not shift! I have tried playing with the kickdown, and fiddling (rotating 2 times ccw) with the vacuum modulator with very little in the way of results.

The vac modulator does not appear to be leaking fluid - can it still be malfunctioning? It was replaced less than 1500mi ago and seemed to be good for about 1000mi.

I was under the impression that even if the modulator isnt working the governor should kick in at some point (5-6k) and force a shift. I dont think I can go any higher than 6700 to see if its going to shift without endangering my engine.

I am scheduled to goto a track day in 36 hours so any help is much appreciated!!

 

302 coupe

Founding Member

Mar 2, 2000

1,952

3

36

Macon, Ga.

Dec 12, 2006

#2

• Dec 12, 2006

• #2

the governor might be stuck.

You can always just shift it manually, it should shift as soon as you select the next gear.

 

C

C0V3R

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Feb 14, 2003

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Dec 12, 2006

#3

• Dec 12, 2006

• #3

Is there any way you can un stick it without pulling apart the transmission?

 

302 coupe

Founding Member

Mar 2, 2000

1,952

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36

Macon, Ga.

Dec 12, 2006

#4

• Dec 12, 2006

• #4

you could try some of those magical additives, it would be a longshot though. Best bet would be to remove the driveshaft and extension housing from the trans. The governor is pretty easy to get to. Remove, inspect, clean, reinstall, and keep your fingers crossed.

You can shift it manually, right???

 

C

C0V3R

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Dec 12, 2006

#5

• Dec 12, 2006

• #5

Not sure if I can manually shift it at WOT. Do you think it would work?

 

iskwezm

10 Year Member

May 24, 2005

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79

Rowland Heights,California

Dec 12, 2006

#6

• Dec 12, 2006

• #6

The vac modulator is on the pass. side of the trans. Make sure the line isnt kinked or the rubber line isnt rotted or sucking fluid. Its a cheap part and quick replacement if it used to work.

 

C

C0V3R

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Dec 12, 2006

#7

• Dec 12, 2006

• #7

The VM is not sucking fluid and has new rubber line to it. I hooked up a vac gauge and it is definitely getting vacuum.

 

302 coupe

Founding Member

Mar 2, 2000

1,952

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36

Macon, Ga.

Dec 13, 2006

#8

• Dec 13, 2006

• #8

C0V3R said:

Not sure if I can manually shift it at WOT. Do you think it would work?

Click to expand...

Everybody that drag races with a C4 always shifts manually at WOT. It never crossed your mind to try????

 

C

C0V3R

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Feb 14, 2003

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Dec 13, 2006

#9

• Dec 13, 2006

• #9

I've replaced the modulator, changed the fluid, added additives, changed the lines all with no success.

I tried doing a neutral/drive drop to unstick the governor and at 3000rpm it would not drop into drive. :roll:

 

C

C0V3R

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Feb 14, 2003

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Dec 13, 2006

#10

• Dec 13, 2006

• #10

302 coupe said:

Everybody that drag races with a C4 always shifts manually at WOT. It never crossed your mind to try????

Click to expand...

No because I wanted it to shift lower not higher and I assumed whatever was wrong with it would affect that shifting too.

If I shift manually into D (when in 2nd) it happily stays in second until you let off the throttle. Same deal with 1-2

 

302 coupe

Founding Member

Mar 2, 2000

1,952

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36

Macon, Ga.

Dec 13, 2006

#11

• Dec 13, 2006

• #11

it should shift when you tell it to, regardless of throttle position. Every C4 I've ever had (been a bunch too) always shifted within half a second of me selecting the next gear, no matter the throttle position or rpm. There might be something wrong with your valve body.