c6 Kickdown Problems
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c6 Kickdown Problems
I have a 1988 E350 with a 460 and a C6 tranny. 106k miles.
The kickdown on my tranny had not worked for some time then the catalytic convertor went bad. I replaced it and all of a sudden the kickdown worked.
Then it stopped working unitl I did a tune up. Then it started working again.
Today it stopped working again unless I really stomp on the accelerator (and I mean stomp)
I have a few questions.
1. I wonder if the kickdown problem is associated with any of the above situations or is it coincidence that it starts working when I change something else? Opinions? Could it be a sticking cable or something like that?
2. Should the transmission kickdown from 2nd to 1st as well as from 3rd to 2nd? Seems like it should if I am going slow enough but I don't think it does.
The kickdown on my tranny had not worked for some time then the catalytic convertor went bad. I replaced it and all of a sudden the kickdown worked.
Then it stopped working unitl I did a tune up. Then it started working again.
Today it stopped working again unless I really stomp on the accelerator (and I mean stomp)
I have a few questions.
1. I wonder if the kickdown problem is associated with any of the above situations or is it coincidence that it starts working when I change something else? Opinions? Could it be a sticking cable or something like that?
2. Should the transmission kickdown from 2nd to 1st as well as from 3rd to 2nd? Seems like it should if I am going slow enough but I don't think it does.
Post Fiend
Joined: Jul 2003
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From: Spokane, WA
Your kickdown should drop you one gear, whether it be from 3rd to 2nd or 2nd to 3rd. The kickdown on the C6 is purely mechanical, when the accelerator is pushed to a certain point the kickdown rod (or cable) pushed the kickdown lever on the tranny and it automatically downshifts. The cat and the tune up really shouldn't affect anything with the kick down. You may want to try adjusting the rod or cable at the carb and see if that helps. If you climb under the truck and have someone press the acceletator to the floor (engine off . . . safety first! 
) you can see the kickdown lever move. If it doesn't move all the way just make the appropriate adjustment and you'll be good to go. 
) you can see the kickdown lever move. If it doesn't move all the way just make the appropriate adjustment and you'll be good to go.
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I changed the modulator a month or two ago when I thought I was having some shift problems with the tranny. There was a little fluid in the hose but putting on a new modulator did nothing for the kickdown issue, which just happened to not be working at that time. During my recent tune up I checked the vac hose at the manifold and it seemed OK.
There has been some discussion in the past as to whether or not the modulator effects the kickdown on a C6 and according to the experts it shouldn't have anything to do with it. However, since the modulator does affect shifting it would seem logical that the modulator would be involved in the kickdown function. Another however, if I accelerate quickly (press the pedal to the floor) the shift point from second to third happens at a much higher speed than if I just take off slowly. Doesn't that indicate that the modulator is working? Also, if I stop on a hill and take off the tranny stays in first until I level out a bit. Is that also an indication that the modulator is working properly?
Experts - does the modulator have anything to do with kickdown in a C6 transmission?
There has been some discussion in the past as to whether or not the modulator effects the kickdown on a C6 and according to the experts it shouldn't have anything to do with it. However, since the modulator does affect shifting it would seem logical that the modulator would be involved in the kickdown function. Another however, if I accelerate quickly (press the pedal to the floor) the shift point from second to third happens at a much higher speed than if I just take off slowly. Doesn't that indicate that the modulator is working? Also, if I stop on a hill and take off the tranny stays in first until I level out a bit. Is that also an indication that the modulator is working properly?
Experts - does the modulator have anything to do with kickdown in a C6 transmission?
Last edited by mpmccarthy; Jul 13, 2004 at 07:02 AM.
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I THINK THE PROBLEM IS SOLVED!!!
Ivanribic - I took your advise and had my wife press the accelerator to the floor while I was under the vehcile. Nothing - the kickdown lever didn't move. I had her try it several times.
When I got out from under the vehicle (which is a motorhome) I asked my wife to show me exactly what she did (you can never be too careful). She pushed the accelertor to the floor.
AND THEN IT HIT ME.
My wife, in an effort to dress up the motorhome a little, added carpet and a floor mat. When I was doing the tune up, etc., I removed the carpet and floor mat. I would test drive it and I was amazed at how much improvement I got in performance after my excellent work. When I finished working on it she put the carpet and floor mat back in. As a result WOT was not WOT but something a little less. No wonder the performace of the engine, and the kickdown, kept changing. With the carpet and floor mat in I was never getting WOT.
As they say, KISS.
Ivanribic - I took your advise and had my wife press the accelerator to the floor while I was under the vehcile. Nothing - the kickdown lever didn't move. I had her try it several times.
When I got out from under the vehicle (which is a motorhome) I asked my wife to show me exactly what she did (you can never be too careful). She pushed the accelertor to the floor.
AND THEN IT HIT ME.
My wife, in an effort to dress up the motorhome a little, added carpet and a floor mat. When I was doing the tune up, etc., I removed the carpet and floor mat. I would test drive it and I was amazed at how much improvement I got in performance after my excellent work. When I finished working on it she put the carpet and floor mat back in. As a result WOT was not WOT but something a little less. No wonder the performace of the engine, and the kickdown, kept changing. With the carpet and floor mat in I was never getting WOT.
As they say, KISS.
Last edited by mpmccarthy; Jul 13, 2004 at 08:15 AM.
Post Fiend
Joined: Jul 2003
Posts: 11,945
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From: Spokane, WA
Okay, that's actually kind of funny about the carpet. 
I never would have thought of that but it's amazing what just a little bit of movement can do. Silly women and their "pretty things". 
I'm not an expert but I don't believe the modulator has anything to do with the kickdown feature, only regular shifting.
I never would have thought of that but it's amazing what just a little bit of movement can do. Silly women and their "pretty things". I'm not an expert but I don't believe the modulator has anything to do with the kickdown feature, only regular shifting.
Postmaster
Joined: Dec 2002
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From: USA
LOL, I got a kick out of that carpet thing! 
It makes sense when ya think about it though. Maybe I aughta take the carpet out of my truck and see if goes any faster...
Yeah, the tranny holding in gear longer when hard accelerating or starting off on a hill does indicate the modulator is working correctly. I have no idea if the modulator has anything to do with the kickdown somehow but it doesn't appear to, to me anyways.
It makes sense when ya think about it though. Maybe I aughta take the carpet out of my truck and see if goes any faster... Yeah, the tranny holding in gear longer when hard accelerating or starting off on a hill does indicate the modulator is working correctly. I have no idea if the modulator has anything to do with the kickdown somehow but it doesn't appear to, to me anyways.
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