C6 shifting problem. Need advice
Posting Guru
Joined: Jul 2004
Posts: 1,627
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From: West Valley Utah
If the modulator isn't working correctly it can cause anything from slow, erratic shifts to harsh, slam into gear shifts. It will have a hard time going into third until the rpm's get pretty high then it'll slam into 3rd, first to second can shift ok although pretty harsh even under a light throttle. Try hand shifting the gear selector starting in low and see if it'll shift into 3rd that way. If you put the selector in Drive 2 it will start out in second and will not shift back into D1 even if you come to a stop so make sure you start in D1 when hand shifting.
I still think you have a vacuum problem. Pull the vacuum line off the modulator and if tranny fluid comes out, the modulator is bad.
I still think you have a vacuum problem. Pull the vacuum line off the modulator and if tranny fluid comes out, the modulator is bad.
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Freshman User
Joined: Sep 2004
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Pulled the line to modulator. Nice and dry, no fluid. Have 13" vacuum at idle at IP and at line to modulator. Can't find my vacuum pump to test value at throttle Wide open. It should be 6"-8" on VRV. Will try to get it checked tonight.
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Freshman User
Joined: Sep 2004
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Well, I got a cacuum pump and tryied to check my VRV. I only get 13" at IP and when I open throttle, it drops down to 5" or less. So, it is not working properly. Tried to adjust it, but no change really. Dealer wants $100.00 fro a new one. Installed a new modulator tonight as well, but have not tested it yet. I wonder if my vacuum pump is bad as well. I will test it tomorrow night to see what kind of number I get with engine running.
Anyone know of a place to get a Vacuum regulating valve cheaper than dealer?
NAPA couldn't help me tonight, but they might have them. will check tomorrow, now that I have the FORD number.
Anyone know of a place to get a Vacuum regulating valve cheaper than dealer?
NAPA couldn't help me tonight, but they might have them. will check tomorrow, now that I have the FORD number.
Mountain Pass
Joined: Jun 2004
Posts: 241
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From: Canada
Where are you measuring the vacuum? Should be at the modulator. 13 at the source of the vrv should be right at the edge. If it drops to 5 at the modulator,at wide open throttle, the vrv is working. Try the modulator first before spending more cash. Modulators out of the box are adjusted real close. How much vacuum is the pump puting out? Don
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Joined: Sep 2004
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It measures the same at modulator, and at port on VRV. What i saw last night is that at times while flipping open the throttle, the vacuum would sometimes go below 5", even to 0". I would keep it there (Throttle open)and it should slowly build up vacuum again, but it didn't. I don't know what is going on with the VRV. This is what I understand from what I have been told by my transmission shop.
That when throttle opens, the vacuuum should drop to 6-8", then slowly build back up to about 20". When it builds back up, that is what actually allows the tranny to shift. So, if I cannot get enough vacuum to the modulator, it will just stay in second gear. Apparently, the tranny can shift into 1 and 2, which is what I have, but not into 3 because of a vacuum issue.
I had a vacuum pump and was keeping it at 20" to test VRV, so I think it is bad. I will be checking the pump tonight to see if it may not be producing enough vac either.
That when throttle opens, the vacuuum should drop to 6-8", then slowly build back up to about 20". When it builds back up, that is what actually allows the tranny to shift. So, if I cannot get enough vacuum to the modulator, it will just stay in second gear. Apparently, the tranny can shift into 1 and 2, which is what I have, but not into 3 because of a vacuum issue.
I had a vacuum pump and was keeping it at 20" to test VRV, so I think it is bad. I will be checking the pump tonight to see if it may not be producing enough vac either.
