Wild Tach Swing
Senior User
Joined: Feb 2002
Posts: 132
Likes: 0
From: South Bend
Wild Tach Swing
I'm getting a wild tach swing at around 1500 RPM in OD at 50mph. If I keep it under 50 I don't have the problem. It doesn't happen in any other gear at low speed. I'm going to try driving home in 3rd and see if it happens at speed then. Anyone have any ideas? I have a 1988 Bronco with the 5.0 and the AOD tranny. The only mods are headers and a K&N Filtercharger. I installed a new longblock about a year ago and only have about 5000 miles on it. I'm not sure it's related but I've had a nasty vibration at highway speeds (anything over 45 for quite a while. I thought that was the driveshaft but now I'm not sure.
John Green
1988 Ford Bronco 5.0
1997 Ford Mustang Cobra
John Green
1988 Ford Bronco 5.0
1997 Ford Mustang Cobra
Freshman User
Joined: Nov 2002
Posts: 46
Likes: 0
From: Las Vegas US
Wild Tach Swing
For what it's worth, I had a similiar problem and it turned out to be the ignition module on the distributer. It started as just a bounce or drop in the tach and progressed to the engine cutting out for a split second every now and again. Then it just quit all together. $50 for a new module and the little tool to get it apart and it was back in business. The modules are infamous for trouble too. Hope that helps.
