a4ld won't shift into overdrive

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Bob Weir
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Re: a4ld won't shift into overdrive

Post by Bob Weir » Wed Sep 16, 2020 8:47 am

Thanks for the correction.

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Re: a4ld won't shift into overdrive

Post by andyofcolumbusmerkur » Thu Sep 17, 2020 7:39 am

On my automatic vehicle (the work truck) I did the pump out the ATF and add what you pump out method. This was at the same time I bypassed the stock cooler, which is inside the radiator, for a proper front mount cooler. Since I had to run high pressure hose to install the new cooler it was very easy to put the end of the hose into a gallon jug. Pump out a quart or two and add it back in. I got a couple big containers of autozone brand ATF and their assorted container of high pressure hose clamps.
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Re: a4ld won't shift into overdrive

Post by brokencase » Fri Sep 18, 2020 2:45 pm

Here is the aftermarket switch up on ebay.. Superior makes it.

https://www.ebay.com/itm/Adjustable-Vac ... 2359828359

Just an FYI - You can tell if this vacuum switch is not adjusted properly (or if there is a leak in the line going to it) if you feel the torque converter release "harshly and late" as you approach a stop from a long stretch when you were doing above 50mph and you let off the gas as you come to the stop.

Sometimes you can work around the harsh release (and confirm the issue) by forcing higher than normal manifold vacuum by blipping the throttle a little before you would normally feel the harsh release under the same circumstance of approaching the stop. The short blip of the throttle raises RPMS and then the throttle blades shut and you get a pulse of higher than normal vacuum that may trip the mal-adjusted switch.

Hard to describe...but I've been there. It goes without saying that any other vacuum leak in the system can impact the behavior of this switch plus cause a lot of other undesirable behaviors that can compound the diagnosis. Not a bad idea to hook up a vacuum gauge once in a while.
Last edited by brokencase on Fri Sep 18, 2020 5:33 pm, edited 2 times in total.

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Re: a4ld won't shift into overdrive

Post by asifahmed » Fri Sep 18, 2020 5:14 pm

Brokencase beat me to it..but here a link to superior's website

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Re: a4ld won't shift into overdrive

Post by Ed Lijewski » Mon Sep 21, 2020 7:28 am

I haven't needed to try it but I think the OEM switch is adjustable. Under the plastic cap is a hex head bolt which can be turned right/left.

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Re: a4ld won't shift into overdrive

Post by Merkurfast » Sun Sep 27, 2020 7:39 pm

Ive had the same problem with my Scorpio not shifting into 4th or overdrive. I replaced the vacuum modulator. I tested the vacuum switch on the airbox by trying to put a vacuum on it. It would not vacuum hold very well even after i took it apart and put some silicone tape on the threads. It probably needs replacing. How does that switch affect shifting into 4th?

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